Android Lint Checks

Here are the current list of checks that lint performs as of Android Studio 2.3 dev:

Correctness

===========

AdapterViewChildren

-------------------

Summary: AdapterViews cannot have children in XML

Priority: 10 / 10

Severity: Warning

Category: Correctness

AdapterViews such as ListViews must be configured with data from Java code,

such as a ListAdapter.

More information:

http://developer.android.com/reference/android/widget/AdapterView.html

OnClick

-------

Summary: onClick method does not exist

Priority: 10 / 10

Severity: Error

Category: Correctness

The onClick attribute value should be the name of a method in this View's

context to invoke when the view is clicked. This name must correspond to a

public method that takes exactly one parameter of type View.

Must be a string value, using ';' to escape characters such as '
' or

'uxxxx' for a unicode character.

StopShip

--------

Summary: Code contains STOPSHIP marker

Priority: 10 / 10

Severity: Warning

Category: Correctness

NOTE: This issue is disabled by default!

You can enable it by adding --enable StopShip

Using the comment // STOPSHIP can be used to flag code that is incomplete but

checked in. This comment marker can be used to indicate that the code should

not be shipped until the issue is addressed, and lint will look for these.

MissingPermission

-----------------

Summary: Missing Permissions

Priority: 9 / 10

Severity: Error

Category: Correctness

This check scans through your code and libraries and looks at the APIs being

used, and checks this against the set of permissions required to access those

APIs. If the code using those APIs is called at runtime, then the program will

crash.

Furthermore, for permissions that are revocable(可撤销的) (with targetSdkVersion 23),

client code must also be prepared to handle the calls throwing an exception if

the user rejects the request for permission at runtime.

MissingSuperCall

----------------

Summary: Missing Super Call

Priority: 9 / 10

Severity: Error

Category: Correctness

Some methods, such as View#onDetachedFromWindow, require that you also call

the super implementation as part of your method.

ResAuto

-------

Summary: Hardcoded Package in Namespace

Priority: 9 / 10

Severity: Fatal

Category: Correctness

In Gradle projects, the actual package used in the final APK can vary; for

example,you can add a .debug package suffix in one version and not the other.

Therefore, you should not hardcode the application package in the resource;

instead, use the special namespace http://schemas.android.com/apk/res-auto

which will cause the tools to figure out the right namespace for the resource

regardless of the actual package used during the build.

SuspiciousImport

----------------

Summary: 'import android.R' statement

Priority: 9 / 10

Severity: Warning

Category: Correctness

Importing android.R is usually not intentional(故意的); it sometimes happens when you

use an IDE and ask it to automatically add imports at a time when your

project's R class it not present.

Once the import is there you might get a lot of "confusing" error messages

because of course the fields available on android.R are not the ones you'd

expect from just looking at your own R class.

UsesMinSdkAttributes

--------------------

Summary: Minimum SDK and target SDK attributes not defined

Priority: 9 / 10

Severity: Warning

Category: Correctness

The manifest should contain a <uses-sdk> element which defines the minimum API

Level required for the application to run, as well as the target version (the

highest API level you have tested the version for.)

More information:

http://developer.android.com/guide/topics/manifest/uses-sdk-element.html

WrongViewCast

-------------

Summary: Mismatched view type

Priority: 9 / 10

Severity: Fatal

Category: Correctness

Keeps track of the view types associated with ids and if it finds a usage of

the id in the Java code it ensures that it is treated as the same type.

AaptCrash

---------

Summary: Potential AAPT crash

Priority: 8 / 10

Severity: Fatal

Category: Correctness

Defining a style which sets android:id to a dynamically(动态地) generated id can cause

many versions of aapt, the resource packaging tool, to crash. To work around

this, declare the id explicitly with <item type="id" name="..." /> instead.

More information:

https://code.google.com/p/android/issues/detail?id=20479

GradleCompatible

----------------

Summary: Incompatible(不相容的) Gradle Versions

Priority: 8 / 10

Severity: Error

Category: Correctness

There are some combinations of libraries, or tools and libraries, that are

incompatible(不相容的), or can lead to bugs. One such incompatibility(不相容) is compiling with

a version of the Android support libraries that is not the latest version (or

in particular, a version lower than your targetSdkVersion.)

GradlePluginVersion

-------------------

Summary: Incompatible Android Gradle Plugin

Priority: 8 / 10

Severity: Error

Category: Correctness

Not all versions of the Android Gradle plugin are compatible with all versions

of the SDK. If you update your tools, or if you are trying to open a project

that was built with an old version of the tools, you may need to update your

plugin version number.

IllegalResourceRef

------------------

Summary: Name and version must be integer or string, not resource

Priority: 8 / 10

Severity: Warning

Category: Correctness

For the versionCode attribute, you have to specify an actual integer literal;

you cannot use an indirection(间接) with a @dimen/name resource. Similarly, the

versionName attribute should be an actual string, not a string resource url.

MergeMarker

-----------

Summary: Code contains merge marker

Priority: 8 / 10

Severity: Error

Category: Correctness

Many version control systems leave unmerged files with markers such as <<< in

the source code. This check looks for these markers, which are sometimes

accidentally left in, particularly in resource files where they don't break

compilation.

MissingLeanbackLauncher

-----------------------

Summary: Missing Leanback Launcher Intent Filter.

Priority: 8 / 10

Severity: Error

Category: Correctness

An application intended to run on TV devices must declare a launcher activity

for TV in its manifest using a android.intent.category.LEANBACK_LAUNCHER

intent filter.

More information:

https://developer.android.com/training/tv/start/start.html#tv-activity

MissingRegistered

-----------------

Summary: Missing registered class

Priority: 8 / 10

Severity: Error

Category: Correctness

If a class is referenced in the manifest or in a layout file, it must also

exist in the project (or in one of the libraries included by the project. This

check helps uncover typos in registration names, or attempts to rename or move

classes without updating the manifest file properly.

More information:

http://developer.android.com/guide/topics/manifest/manifest-intro.html

MockLocation

------------

Summary: Using mock location provider in production

Priority: 8 / 10

Severity: Fatal

Category: Correctness

Using a mock location provider (by requiring the permission

android.permission.ACCESS_MOCK_LOCATION) should only be done in debug builds

(or from tests). In Gradle projects, that means you should only request this

permission in a test or debug source set specific manifest file.

To fix this, create a new manifest file in the debug folder and move the

<uses-permission> element there. A typical path to a debug manifest override

file in a Gradle project is src/debug/AndroidManifest.xml.

NamespaceTypo

-------------

Summary: Misspelled namespace declaration

Priority: 8 / 10

Severity: Fatal

Category: Correctness

Accidental misspellings in namespace declarations can lead to some very

obscure error messages. This check looks for potential misspellings to help

track these down.

NotInterpolated

---------------

Summary: Incorrect Interpolation(插入)

Priority: 8 / 10

Severity: Error

Category: Correctness

To insert the value of a variable, you can use ${variable} inside a string

literal, but only if you are using double quotes!

More information:

http://www.groovy-lang.org/syntax.html#_string_interpolation

PendingBindings

---------------

Summary: Missing Pending Bindings

Priority: 8 / 10

Severity: Error

Category: Correctness

When using a ViewDataBinding in a onBindViewHolder method, you must call

executePendingBindings() before the method exits; otherwise the data binding

runtime will update the UI in the next animation frame causing a delayed

update and potential jumps if the item resizes.

Proguard

--------

Summary: Using obsolete ProGuard configuration

Priority: 8 / 10

Severity: Fatal

Category: Correctness

Using -keepclasseswithmembernames in a proguard config file is not correct; it

can cause some symbols to be renamed which should not be.

Earlier versions of ADT used to create proguard.cfg files with the wrong

format. Instead of -keepclasseswithmembernames use -keepclasseswithmembers,

since the old flags also implies "allow shrinking" which means symbols only

referred to from XML and not Java (such as possibly CustomViews) can get

deleted.

More information:

http://http://code.google.com/p/android/issues/detail?id=16384

RecyclerView

------------

Summary: RecyclerView Problems

Priority: 8 / 10

Severity: Error

Category: Correctness

RecyclerView will not call onBindViewHolder again when the position of the

item changes in the data set unless the item itself is invalidated(无效) or the new

position cannot be determined.

For this reason, you should only use the position parameter while acquiring

the related data item inside this method, and should not keep a copy of it.

If you need the position of an item later on (e.g. in a click listener), use

getAdapterPosition() which will have the updated adapter position.

ReferenceType

-------------

Summary: Incorrect reference types

Priority: 8 / 10

Severity: Fatal

Category: Correctness

When you generate a resource alias, the resource you are pointing to must be

of the same type as the alias

ResourceCycle

-------------

Summary: Cycle in resource definitions

Priority: 8 / 10

Severity: Fatal

Category: Correctness

There should be no cycles in resource definitions as this can lead to runtime

exceptions.

ResourceName

------------

Summary: Resource with Wrong Prefix

Priority: 8 / 10

Severity: Fatal

Category: Correctness

In Gradle projects you can specify a resource prefix that all resources in the

project must conform to. This makes it easier to ensure that you don't

accidentally combine resources from different libraries, since they all end up

in the same shared app namespace.

ScrollViewCount

---------------

Summary: ScrollViews can have only one child

Priority: 8 / 10

Severity: Warning

Category: Correctness

ScrollViews can only have one child widget. If you want more children, wrap

them in a container layout.

StringShouldBeInt

-----------------

Summary: String should be int

Priority: 8 / 10

Severity: Error

Category: Correctness

The properties compileSdkVersion, minSdkVersion and targetSdkVersion are

usually numbers, but can be strings when you are using an add-on (in the case

of compileSdkVersion) or a preview platform (for the other two properties).

However, you can not use a number as a string (e.g. "19" instead of 19); that

will result in a platform not found error message at build/sync time.

UnknownId

---------

Summary: Reference to an unknown id

Priority: 8 / 10

Severity: Fatal

Category: Correctness

The @+id/ syntax refers to an existing id, or creates a new one if it has not

already been defined elsewhere. However, this means that if you have a typo in

your reference, or if the referred view no longer exists, you do not get a

warning since the id will be created on demand. This check catches errors

where you have renamed an id without updating all of the references to it.

WrongFolder

-----------

Summary: Resource file in the wrong res folder

Priority: 8 / 10

Severity: Fatal

Category: Correctness

Resource files are sometimes placed in the wrong folder, and it can lead to

subtle bugs that are hard to understand. This check looks for problems in this

area, such as attempting to place a layout "alias" file in a layout/ folder

rather than the values/ folder where it belongs.

CommitTransaction

-----------------

Summary: Missing commit() calls

Priority: 7 / 10

Severity: Warning

Category: Correctness

After creating a FragmentTransaction, you typically need to commit it as well

DalvikOverride

--------------

Summary: Method considered overridden(蹂躏) by Dalvik

Priority: 7 / 10

Severity: Error

Category: Correctness

The Android virtual machine will treat a package private method in one class

as overriding a package private method in its super class, even if they are in

separate packages. This may be surprising, but for compatibility reasons the

behavior has not been changed (yet).

If you really did intend for this method to override the other, make the

method protected instead.

If you did not intend the override, consider making the method private, or

changing its name or signature.

DeviceAdmin

-----------

Summary: Malformed(畸形) Device Admin

Priority: 7 / 10

Severity: Warning

Category: Correctness

If you register a broadcast receiver which acts as a device admin, you must

also register an <intent-filter> for the action

android.app.action.DEVICE_ADMIN_ENABLED, without any <data>, such that the

device admin can be activated/deactivated(无效的).

To do this, add

<intent-filter>

<action android:name="android.app.action.DEVICE_ADMIN_ENABLED" />

</intent-filter>

to your <receiver>.

DuplicateIds

------------

Summary: Duplicate ids within a single layout

Priority: 7 / 10

Severity: Fatal

Category: Correctness

Within a layout, id's should be unique since otherwise findViewById() can

return an unexpected view.

InconsistentArrays

------------------

Summary: Inconsistencies(不一致) in array element counts

Priority: 7 / 10

Severity: Warning

Category: Correctness

When an array is translated in a different locale, it should normally have the

same number of elements as the original array. When adding or removing

elements to an array, it is easy to forget to update all the locales, and this

lint warning finds inconsistencies(不一致) like these.

Note however that there may be cases where you really want to declare a

different number of array items in each configuration (for example where the

array represents available options, and those options differ for different

layout orientations and so on), so use your own judgement to decide if this is

really an error.

You can suppress this error type if it finds false errors in your project.

MissingTvBanner

---------------

Summary: TV Missing Banner

Priority: 7 / 10

Severity: Error

Category: Correctness

A TV application must provide a home screen banner for each localization if it

includes a Leanback launcher intent filter. The banner is the app launch point

that appears on the home screen in the apps and games rows.

More information:

http://developer.android.com/training/tv/start/start.html#banner

NestedScrolling

---------------

Summary: Nested scrolling widgets

Priority: 7 / 10

Severity: Warning

Category: Correctness

A scrolling widget such as a ScrollView should not contain any nested

scrolling widgets since this has various usability issues

ResourceAsColor

---------------

Summary: Should pass resolved color instead of resource id

Priority: 7 / 10

Severity: Error

Category: Correctness

Methods that take a color in the form of an integer should be passed an RGB

triple, not the actual color resource id. You must call

getResources().getColor(resource) to resolve the actual color value first.

ResourceType

------------

Summary: Wrong Resource Type

Priority: 7 / 10

Severity: Fatal

Category: Correctness

Ensures that resource id's passed to APIs are of the right type; for example,

calling Resources.getColor(R.string.name) is wrong.

ScrollViewSize

--------------

Summary: ScrollView size validation

Priority: 7 / 10

Severity: Warning

Category: Correctness

ScrollView children must set their layout_width or layout_height attributes to

wrap_content rather than fill_parent or match_parent in the scrolling

dimension

TextViewEdits

-------------

Summary: TextView should probably be an EditText instead

Priority: 7 / 10

Severity: Warning

Category: Correctness

Using a <TextView> to input text is generally an error, you should be using

<EditText> instead. EditText is a subclass(亚纲) of TextView, and some of the

editing support is provided by TextView, so it's possible to set some

input-related properties on a TextView. However, using a TextView along with

input attributes is usually a cut & paste error. To input text you should be

using <EditText>.

This check also checks subclasses of TextView, such as Button and CheckBox,

since these have the same issue: they should not be used with editable

attributes.

WebViewLayout

-------------

Summary: WebViews in wrap_content parents

Priority: 7 / 10

Severity: Error

Category: Correctness

The WebView implementation has certain performance optimizations which will

not work correctly if the parent view is using wrap_content rather than

match_parent. This can lead to subtle UI bugs.

AppCompatMethod

---------------

Summary: Using Wrong AppCompat Method

Priority: 6 / 10

Severity: Warning

Category: Correctness

When using the appcompat library, there are some methods you should be calling

instead of the normal ones; for example, getSupportActionBar() instead of

getActionBar(). This lint check looks for calls to the wrong method.

More information:

http://developer.android.com/tools/support-library/index.html

ApplySharedPref

---------------

Summary: Use apply() on SharedPreferences

Priority: 6 / 10

Severity: Warning

Category: Correctness

Consider using apply() instead of commit on shared preferences. Whereas commit

blocks and writes its data to persistent storage immediately, apply will

handle it in the background.

Assert

------

Summary: Assertions

Priority: 6 / 10

Severity: Warning

Category: Correctness

Assertions(断言) are not checked at runtime. There are ways to request that they be

used by Dalvik (adb shell setprop debug.assert 1), but the property is ignored

in many places and can not be relied upon. Instead, perform conditional(有条件的)

checking inside if (BuildConfig.DEBUG) { } blocks. That constant is a static

final boolean which is true in debug builds and false in release builds, and

the Java compiler completely removes all code inside the if-body from the

app.

For example, you can replace assert speed > 0 with if (BuildConfig.DEBUG &&

!(speed > 0)) { throw new AssertionError() }.

(Note: This lint check does not flag assertions purely asserting nullness or

non-nullness; these are typically more intended for tools usage than runtime

checks.)

More information:

https://code.google.com/p/android/issues/detail?id=65183

CheckResult

-----------

Summary: Ignoring results

Priority: 6 / 10

Severity: Warning

Category: Correctness

Some methods have no side effects, an calling them without doing something

without the result is suspicious.

CommitPrefEdits

---------------

Summary: Missing commit() on SharedPreference editor

Priority: 6 / 10

Severity: Warning

Category: Correctness

After calling edit() on a SharedPreference, you must call commit() or apply()

on the editor to save the results.

CustomViewStyleable

-------------------

Summary: Mismatched Styleable/Custom View Name

Priority: 6 / 10

Severity: Warning

Category: Correctness

The convention for custom views is to use a declare-styleable whose name

matches the custom view class name. The IDE relies on this convention such

that for example code completion can be offered for attributes in a custom

view in layout XML resource files.

(Similarly, layout parameter classes should use the suffix _Layout.)

CutPasteId

----------

Summary: Likely cut & paste mistakes

Priority: 6 / 10

Severity: Warning

Category: Correctness

This lint check looks for cases where you have cut & pasted calls to

findViewById but have forgotten to update the R.id field. It's possible that

your code is simply (redundantly(多余地)) looking up the field repeatedly, but lint

cannot distinguish that from a case where you for example want to initialize

fields prev and next and you cut & pasted findViewById(R.id.prev) and forgot

to update the second initialization(初始化) to R.id.next.

DefaultLocale

-------------

Summary: Implied default locale in case conversion

Priority: 6 / 10

Severity: Warning

Category: Correctness

Calling String#toLowerCase() or #toUpperCase() without specifying an explicit

locale is a common source of bugs. The reason for that is that those methods

will use the current locale on the user's device, and even though the code

appears to work correctly when you are developing the app, it will fail in

some locales. For example, in the Turkish locale, the uppercase(以大写字母印刷) replacement

for i is not I.

If you want the methods to just perform ASCII replacement, for example to

convert an enum name, call String#toUpperCase(Locale.US) instead. If you

really want to use the current locale, call

String#toUpperCase(Locale.getDefault()) instead.

More information:

http://developer.android.com/reference/java/util/Locale.html#default_locale

DuplicateDefinition

-------------------

Summary: Duplicate definitions of resources

Priority: 6 / 10

Severity: Error

Category: Correctness

You can define a resource multiple times in different resource folders; that's

how string translations are done, for example. However, defining the same

resource more than once in the same resource folder is likely an error, for

example attempting to add a new resource without realizing that the name is

already used, and so on.

DuplicateIncludedIds

--------------------

Summary: Duplicate ids across layouts combined with include tags

Priority: 6 / 10

Severity: Warning

Category: Correctness

It's okay for two independent layouts to use the same ids. However, if layouts

are combined with include tags, then the id's need to be unique within any

chain of included layouts, or Activity#findViewById() can return an unexpected

view.

GradleDeprecated

----------------

Summary: Deprecated(反对) Gradle Construct

Priority: 6 / 10

Severity: Warning

Category: Correctness

This detector looks for deprecated Gradle constructs which currently work but

will likely stop working in a future update.

GradleGetter

------------

Summary: Gradle Implicit Getter Call

Priority: 6 / 10

Severity: Error

Category: Correctness

Gradle will let you replace specific constants in your build scripts with

method calls, so you can for example dynamically(动态地) compute a version string

based on your current version control revision number, rather than hardcoding

a number.

When computing a version name, it's tempting(诱惑) to for example call the method to

do that getVersionName. However, when you put that method call inside the

defaultConfig block, you will actually be calling the Groovy getter for the

versionName property instead. Therefore, you need to name your method

something which does not conflict with the existing implicit(含蓄的) getters. Consider

using compute as a prefix instead of get.

ImpliedTouchscreenHardware

--------------------------

Summary: Hardware feature touchscreen not explicitly marked as optional

Priority: 6 / 10

Severity: Error

Category: Correctness

Apps require the android.hardware.touchscreen feature by default. If you want

your app to be available on TV, you must also explicitly declare that a

touchscreen is not required as follows:

<uses-feature android:name="android.hardware.touchscreen"

android:required="false"/>

More information:

https://developer.android.com/guide/topics/manifest/uses-feature-element.html

InconsistentLayout

------------------

Summary: Inconsistent(不一致的) Layouts

Priority: 6 / 10

Severity: Warning

Category: Correctness

This check ensures that a layout resource which is defined in multiple

resource folders, specifies the same set of widgets.

This finds cases where you have accidentally forgotten to add a widget to all

variations of the layout, which could result in a runtime crash for some

resource configurations when a findViewById() fails.

There are cases where this is intentional(故意的). For example, you may have a

dedicated large tablet layout which adds some extra widgets that are not

present in the phone version of the layout. As long as the code accessing the

layout resource is careful to handle this properly, it is valid. In that case,

you can suppress this lint check for the given extra or missing views, or the

whole layout

InlinedApi

----------

Summary: Using inlined constants on older versions

Priority: 6 / 10

Severity: Warning

Category: Correctness

This check scans through all the Android API field references in the

application and flags certain constants, such as static final integers and

Strings, which were introduced in later versions. These will actually be

copied into the class files rather than being referenced, which means that the

value is available even when running on older devices. In some cases that's

fine, and in other cases it can result in a runtime crash or incorrect

behavior. It depends on the context, so consider the code carefully and device

whether it's safe and can be suppressed or whether the code needs tbe

guarded.

If you really want to use this API and don't need to support older devices

just set the minSdkVersion in your build.gradle or AndroidManifest.xml files.

If your code is deliberately(故意地) accessing newer APIs, and you have ensured (e.g.

with conditional(有条件的) execution) that this code will only ever be called on a

supported platform, then you can annotate(注释) your class or method with the

@TargetApi annotation specifying the local minimum SDK to apply, such as

@TargetApi(11), such that this check considers 11 rather than your manifest

file's minimum SDK as the required API level.

Instantiatable

--------------

Summary: Registered class is not instantiatable

Priority: 6 / 10

Severity: Fatal

Category: Correctness

Activities, services, broadcast receivers etc. registered in the manifest file

(or for custom views, in a layout file) must be "instantiatable" by the

system, which means that the class must be public, it must have an empty

public constructor, and if it's an inner class, it must be a static inner

class.

InvalidAnalyticsName

--------------------

Summary: Invalid Analytics Name

Priority: 6 / 10

Severity: Error

Category: Correctness

Event names and parameters must follow the naming conventions defined in

the`FirebaseAnalytics#logEvent()` documentation.

More information:

http://firebase.google.com/docs/reference/android/com/google/firebase/analytics/FirebaseAnalytics#logEvent(java.lang.String,%20android.os.Bundle)

InvalidId

---------

Summary: Invalid ID declaration

Priority: 6 / 10

Severity: Fatal

Category: Correctness

An id definition must be of the form @+id/yourname. The tools have not

rejected strings of the form @+foo/bar in the past, but that was an error, and

could lead to tricky errors because of the way the id integers are assigned.

If you really want to have different "scopes" for your id's, use prefixes

instead, such as login_button1 and login_button2.

InvalidPackage

--------------

Summary: Package not included in Android

Priority: 6 / 10

Severity: Error

Category: Correctness

This check scans through libraries looking for calls to APIs that are not

included in Android.

When you create Android projects, the classpath is set up such that you can

only access classes in the API packages that are included in Android. However,

if you add other projects to your libs/ folder, there is no guarantee that

those .jar files were built with an Android specific classpath, and in

particular, they could be accessing unsupported APIs such as java.applet.

This check scans through library jars and looks for references to API packages

that are not included in Android and flags these. This is only an error if

your code calls one of the library classes which wind up referencing the

unsupported package.

InvalidResourceFolder

---------------------

Summary: Invalid Resource Folder

Priority: 6 / 10

Severity: Error

Category: Correctness

This lint check looks for a folder name that is not a valid resource folder

name; these will be ignored and not packaged by the Android Gradle build

plugin.

Note that the order of resources is very important; for example, you can't

specify a language before a network code.

Similarly, note that to use 3 letter region codes, you have to use a special

BCP 47 syntax: the prefix b+ followed by the BCP 47 language tag but with + as

the individual separators instead of -. Therefore, for the BCP 47 language tag

nl-ABW you have to use b+nl+ABW.

More information:

http://developer.android.com/guide/topics/resources/providing-resources.html

https://tools.ietf.org/html/bcp47

InvalidUsesTagAttribute

-----------------------

Summary: Invalid name attribute for uses element.

Priority: 6 / 10

Severity: Error

Category: Correctness

The <uses> element in <automotiveApp> should contain a valid value for the

name attribute.

Valid values are media or notification.

More information:

https://developer.android.com/training/auto/start/index.html#auto-metadata

LibraryCustomView

-----------------

Summary: Custom views in libraries should use res-auto-namespace

Priority: 6 / 10

Severity: Fatal

Category: Correctness

When using a custom view with custom attributes in a library project, the

layout must use the special namespace http://schemas.android.com/apk/res-auto

instead of a URI which includes the library project's own package. This will

be used to automatically adjust the namespace of the attributes when the

library resources are merged into the application project.

LocaleFolder

------------

Summary: Wrong locale name

Priority: 6 / 10

Severity: Warning

Category: Correctness

From the java.util.Locale documentation:

"Note that Java uses several deprecated(反对) two-letter codes. The Hebrew ("he")

language code is rewritten(改写) as "iw", Indonesian ("id") as "in", and Yiddish

("yi") as "ji". This rewriting happens even if you construct your own Locale

object, not just for instances returned by the various lookup methods.

Because of this, if you add your localized(局部的) resources in for example values-he

they will not be used, since the system will look for values-iw instead.

To work around this, place your resources in a values folder using the

deprecated(反对) language code instead.

More information:

http://developer.android.com/reference/java/util/Locale.html

ManifestResource

----------------

Summary: Manifest Resource References

Priority: 6 / 10

Severity: Fatal

Category: Correctness

Elements in the manifest can reference resources, but those resources cannot

vary across configurations (except as a special case, by version, and except

for a few specific package attributes such as the application title and

icon.)

MissingBackupPin

----------------

Summary: Missing Backup Pin

Priority: 6 / 10

Severity: Warning

Category: Correctness

It is highly recommended to declare a backup <pin> element. Not having a

second pin defined can cause connection failures when the particular site

certificate is rotated and the app has not yet been updated.

More information:

https://developer.android.com/preview/features/security-config.html

MissingConstraints

------------------

Summary: Missing Constraints(约束) in ConstraintLayout

Priority: 6 / 10

Severity: Error

Category: Correctness

The layout editor allows you to place widgets anywhere on the canvas, and it

records the current position with designtime attributes (such as

layout_editor_absoluteX.) These attributes are not applied at runtime, so if

you push your layout on a device, the widgets may appear in a different

location than shown in the editor. To fix this, make sure a widget has both

horizontal and vertical constraints by dragging from the edge connections.

MissingIntentFilterForMediaSearch

---------------------------------

Summary: Missing intent-filter with action

android.media.action.MEDIA_PLAY_FROM_SEARCH

Priority: 6 / 10

Severity: Error

Category: Correctness

To support voice searches on Android Auto, you should also register an

intent-filter for the action android.media.action.MEDIA_PLAY_FROM_SEARCH.

To do this, add

<intent-filter>

<action android:name="android.media.action.MEDIA_PLAY_FROM_SEARCH" />

</intent-filter>

to your <activity> or <service>.

More information:

https://developer.android.com/training/auto/audio/index.html#support_voice

MissingLeanbackSupport

----------------------

Summary: Missing Leanback Support.

Priority: 6 / 10

Severity: Error

Category: Correctness

The manifest should declare the use of the Leanback user interface required by

Android TV.

To fix this, add

<uses-feature android:name="android.software.leanback"

android:required="false" />

to your manifest.

More information:

https://developer.android.com/training/tv/start/start.html#leanback-req

MissingMediaBrowserServiceIntentFilter

--------------------------------------

Summary: Missing intent-filter with action

android.media.browse.MediaBrowserService.

Priority: 6 / 10

Severity: Error

Category: Correctness

An Automotive Media App requires an exported service that extends

android.service.media.MediaBrowserService with an intent-filter for the action

android.media.browse.MediaBrowserService to be able to browse and play media.

To do this, add

<intent-filter>

<action android:name="android.media.browse.MediaBrowserService" />

</intent-filter>

to the service that extends android.service.media.MediaBrowserService

More information:

https://developer.android.com/training/auto/audio/index.html#config_manifest

MissingOnPlayFromSearch

-----------------------

Summary: Missing onPlayFromSearch.

Priority: 6 / 10

Severity: Error

Category: Correctness

To support voice searches on Android Auto, in addition to adding an

intent-filter for the action onPlayFromSearch, you also need to override and

implement onPlayFromSearch(String query, Bundle bundle)

More information:

https://developer.android.com/training/auto/audio/index.html#support_voice

MissingPrefix

-------------

Summary: Missing Android XML namespace

Priority: 6 / 10

Severity: Error

Category: Correctness

Most Android views have attributes in the Android namespace. When referencing

these attributes you must include the namespace prefix, or your attribute will

be interpreted by aapt as just a custom attribute.

Similarly, in manifest files, nearly all attributes should be in the android:

namespace.

MultipleUsesSdk

---------------

Summary: Multiple <uses-sdk> elements in the manifest

Priority: 6 / 10

Severity: Fatal

Category: Correctness

The <uses-sdk> element should appear just once; the tools will not merge the

contents of all the elements so if you split up the attributes across multiple

elements, only one of them will take effect. To fix this, just merge all the

attributes from the various elements into a single <uses-sdk> element.

More information:

http://developer.android.com/guide/topics/manifest/uses-sdk-element.html

NewApi

------

Summary: Calling new methods on older versions

Priority: 6 / 10

Severity: Error

Category: Correctness

This check scans through all the Android API calls in the application and

warns about any calls that are not available on all versions targeted by this

application (according to its minimum SDK attribute in the manifest).

If you really want to use this API and don't need to support older devices

just set the minSdkVersion in your build.gradle or AndroidManifest.xml files.

If your code is deliberately(故意地) accessing newer APIs, and you have ensured (e.g.

with conditional(有条件的) execution) that this code will only ever be called on a

supported platform, then you can annotate(注释) your class or method with the

@TargetApi annotation specifying the local minimum SDK to apply, such as

@TargetApi(11), such that this check considers 11 rather than your manifest

file's minimum SDK as the required API level.

If you are deliberately setting android: attributes in style definitions, make

sure you place this in a values-vNN folder in order to avoid running into

runtime conflicts on certain devices where manufacturers have added custom

attributes whose ids conflict with the new ones on later platforms.

Similarly, you can use tools:targetApi="11" in an XML file to indicate that

the element will only be inflated in an adequate context.

NotSibling

----------

Summary: RelativeLayout Invalid Constraints(约束)

Priority: 6 / 10

Severity: Fatal

Category: Correctness

Layout constraints in a given RelativeLayout should reference other views

within the same relative layout (but not itself!)

OldTargetApi

------------

Summary: Target SDK attribute is not targeting latest version

Priority: 6 / 10

Severity: Warning

Category: Correctness

When your application runs on a version of Android that is more recent than

your targetSdkVersion specifies that it has been tested with, various

compatibility modes kick in. This ensures that your application continues to

work, but it may look out of place. For example, if the targetSdkVersion is

less than 14, your app may get an option button in the UI.

To fix this issue, set the targetSdkVersion to the highest available value.

Then test your app to make sure everything works correctly. You may want to

consult the compatibility notes to see what changes apply to each version you

are adding support for:

http://developer.android.com/reference/android/os/Build.VERSION_CODES.html

More information:

http://developer.android.com/reference/android/os/Build.VERSION_CODES.html

Override

--------

Summary: Method conflicts with new inherited method

Priority: 6 / 10

Severity: Error

Category: Correctness

Suppose you are building against Android API 8, and you've subclassed(把…划入亚纲)

Activity. In your subclass you add a new method called isDestroyed(). At some

later point, a method of the same name and signature is added to Android. Your

method will now override the Android method, and possibly break its contract.

Your method is not calling super.isDestroyed(), since your compilation target

doesn't know about the method.

The above scenario is what this lint detector looks for. The above example is

real, since isDestroyed() was added in API 17, but it will be true for any

method you have added to a subclass(亚纲) of an Android class where your build

target is lower than the version the method was introduced in.

To fix this, either rename your method, or if you are really trying to augment(增加)

the builtin method if available, switch to a higher build target where you can

deliberately(故意地) add @Override on your overriding method, and call super if

appropriate etc.

OverrideAbstract

----------------

Summary: Not overriding abstract methods on older platforms

Priority: 6 / 10

Severity: Fatal

Category: Correctness

To improve the usability of some APIs, some methods that used to be abstract

have been made concrete by adding default implementations. This means that

when compiling with new versions of the SDK, your code does not have to

override these methods.

However, if your code is also targeting older versions of the platform where

these methods were still abstract, the code will crash. You must override all

methods that used to be abstract in any versions targeted by your

application's minSdkVersion.

PinSetExpiry

------------

Summary: Validate <pin-set> expiration attribute

Priority: 6 / 10

Severity: Warning

Category: Correctness

Ensures that the expiration attribute of the <pin-set> element is valid and

has not already expired or is expiring soon

More information:

https://developer.android.com/preview/features/security-config.html

PropertyEscape

--------------

Summary: Incorrect property escapes

Priority: 6 / 10

Severity: Error

Category: Correctness

All backslashes(反斜杠) and colons in .property files must be escaped with a backslash

(). This means that when writing a Windows path, you must escape the file

separators, so the path MyFiles should be written as key=\My\Files.

Range

-----

Summary: Outside Range

Priority: 6 / 10

Severity: Error

Category: Correctness

Some parameters are required to in a particular numerical range; this check

makes sure that arguments passed fall within the range. For arrays, Strings

and collections this refers to the size or length.

Registered

----------

Summary: Class is not registered in the manifest

Priority: 6 / 10

Severity: Warning

Category: Correctness

Activities, services and content providers should be registered in the

AndroidManifest.xml file using <activity>, <service> and <provider> tags.

If your activity is simply a parent class intended to be subclassed(把…划入亚纲) by other

"real" activities, make it an abstract class.

More information:

http://developer.android.com/guide/topics/manifest/manifest-intro.html

SdCardPath

----------

Summary: Hardcoded reference to /sdcard

Priority: 6 / 10

Severity: Warning

Category: Correctness

Your code should not reference the /sdcard path directly; instead use

Environment.getExternalStorageDirectory().getPath().

Similarly, do not reference the /data/data/ path directly; it can vary in

multi-user scenarios. Instead, use Context.getFilesDir().getPath().

More information:

http://developer.android.com/guide/topics/data/data-storage.html#filesExternal

ServiceCast

-----------

Summary: Wrong system service casts

Priority: 6 / 10

Severity: Fatal

Category: Correctness

When you call Context#getSystemService(), the result is typically cast to a

specific interface. This lint check ensures that the cast is compatible with

the expected type of the return value.

ShortAlarm

----------

Summary: Short or Frequent Alarm

Priority: 6 / 10

Severity: Warning

Category: Correctness

Frequent alarms are bad for battery life. As of API 22, the AlarmManager will

override near-future and high-frequency alarm requests, delaying the alarm at

least 5 seconds into the future and ensuring that the repeat interval is at

least 60 seconds.

If you really need to do work sooner than 5 seconds, post a delayed message or

runnable(可追捕的) to a Handler.

ShowToast

---------

Summary: Toast created but not shown

Priority: 6 / 10

Severity: Warning

Category: Correctness

Toast.makeText() creates a Toast but does not show it. You must call show() on

the resulting object to actually make the Toast appear.

SimpleDateFormat

----------------

Summary: Implied locale in date format

Priority: 6 / 10

Severity: Warning

Category: Correctness

Almost all callers should use getDateInstance(), getDateTimeInstance(), or

getTimeInstance() to get a ready-made instance of SimpleDateFormat suitable

for the user's locale. The main reason you'd create an instance this class

directly is because you need to format/parse a specific machine-readable(机器可读的)

format, in which case you almost certainly want to explicitly ask for US to

ensure that you get ASCII digits (rather than, say, Arabic digits).

Therefore, you should either use the form of the SimpleDateFormat constructor

where you pass in an explicit locale, such as Locale.US, or use one of the get

instance methods, or suppress this error if really know what you are doing.

More information:

http://developer.android.com/reference/java/text/SimpleDateFormat.html

Suspicious0dp

-------------

Summary: Suspicious 0dp dimension

Priority: 6 / 10

Severity: Error

Category: Correctness

Using 0dp as the width in a horizontal LinearLayout with weights is a useful

trick to ensure that only the weights (and not the intrinsic(本质的) sizes) are used

when sizing the children.

However, if you use 0dp for the opposite dimension, the view will be

invisible. This can happen if you change the orientation of a layout without

also flipping the 0dp dimension in all the children.

UniquePermission

----------------

Summary: Permission names are not unique

Priority: 6 / 10

Severity: Fatal

Category: Correctness

The unqualified names or your permissions must be unique. The reason for this

is that at build time, the aapt tool will generate a class named Manifest

which contains a field for each of your permissions. These fields are named

using your permission unqualified names (i.e. the name portion after the last

dot).

If more than one permission maps to the same field name, that field will

arbitrarily name just one of them.

UnsupportedTvHardware

---------------------

Summary: Unsupported TV Hardware Feature

Priority: 6 / 10

Severity: Error

Category: Correctness

The <uses-feature> element should not require this unsupported TV hardware

feature. Any uses-feature not explicitly marked with required="false" is

necessary on the device to be installed on. Ensure that any features that

might prevent it from being installed on a TV device are reviewed and marked

as not required in the manifest.

More information:

https://developer.android.com/training/tv/start/hardware.html#unsupported-features

UnusedAttribute

---------------

Summary: Attribute unused on older versions

Priority: 6 / 10

Severity: Warning

Category: Correctness

This check finds attributes set in XML files that were introduced in a version

newer than the oldest version targeted by your application (with the

minSdkVersion attribute).

This is not an error; the application will simply ignore the attribute.

However, if the attribute is important to the appearance of functionality of

your application, you should consider finding an alternative way to achieve

the same result with only available attributes, and then you can optionally

create a copy of the layout in a layout-vNN folder which will be used on API

NN or higher where you can take advantage of the newer attribute.

Note: This check does not only apply to attributes. For example, some tags can

be unused too, such as the new <tag> element in layouts introduced in API 21.

UseAlpha2

---------

Summary: Using 3-letter Codes

Priority: 6 / 10

Severity: Warning

Category: Correctness

For compatibility with earlier devices, you should only use 3-letter language

and region codes when there is no corresponding 2 letter code.

More information:

https://tools.ietf.org/html/bcp47

ValidFragment

-------------

Summary: Fragment not instantiatable

Priority: 6 / 10

Severity: Fatal

Category: Correctness

From the Fragment documentation:

Every fragment must have an empty constructor, so it can be instantiated(例示) when

restoring its activity's state. It is strongly recommended that subclasses(亚纲) do

not have other constructors with parameters, since these constructors will not

be called when the fragment is re-instantiated; instead, arguments can be

supplied by the caller with setArguments(Bundle) and later retrieved by the

Fragment with getArguments().

More information:

http://developer.android.com/reference/android/app/Fragment.html#Fragment()

WifiManagerLeak

---------------

Summary: WifiManager Leak

Priority: 6 / 10

Severity: Fatal

Category: Correctness

On versions prior to Android N (24), initializing the WifiManager via

Context#getSystemService can cause a memory leak if the context is not the

application context. Change context.getSystemService(...) to

context.getApplicationContext().getSystemService(...).

WifiManagerPotentialLeak

------------------------

Summary: WifiManager Potential Leak

Priority: 6 / 10

Severity: Warning

Category: Correctness

On versions prior to Android N (24), initializing the WifiManager via

Context#getSystemService can cause a memory leak if the context is not the

application context.

In many cases, it's not obvious from the code where the Context is coming from

(e.g. it might be a parameter to a method, or a field initialized from various

method calls.) It's possible that the context being passed in is the

application context, but to be on the safe side, you should consider changing

context.getSystemService(...) to

context.getApplicationContext().getSystemService(...).

WrongCall

---------

Summary: Using wrong draw/layout method

Priority: 6 / 10

Severity: Fatal

Category: Correctness

Custom views typically need to call measure() on their children, not

onMeasure. Ditto(同上) for onDraw, onLayout, etc.

WrongManifestParent

-------------------

Summary: Wrong manifest parent

Priority: 6 / 10

Severity: Fatal

Category: Correctness

The <uses-library> element should be defined as a direct child of the

<application> tag, not the <manifest> tag or an <activity> tag. Similarly, a

<uses-sdk> tag must be declared at the root level, and so on. This check looks

for incorrect declaration locations in the manifest, and complains if an

element is found in the wrong place.

More information:

http://developer.android.com/guide/topics/manifest/manifest-intro.html

WrongRegion

-----------

Summary: Suspicious Language/Region Combination

Priority: 6 / 10

Severity: Warning

Category: Correctness

Android uses the letter codes ISO 639-1 for languages, and the letter codes

ISO 3166-1 for the region codes. In many cases, the language code and the

country where the language is spoken is the same, but it is also often not the

case. For example, while 'se' refers to Sweden, where Swedish is spoken, the

language code for Swedish is not se (which refers to the Northern Sami

language), the language code is sv. And similarly the region code for sv is El

Salvador.

This lint check looks for suspicious language and region combinations, to help

catch cases where you've accidentally used the wrong language or region code.

Lint knows about the most common regions where a language is spoken, and if a

folder combination is not one of these, it is flagged as suspicious.

Note however that it may not be an error: you can theoretically have speakers

of any language in any region and want to target that with your resources, so

this check is aimed at tracking down likely mistakes, not to enforce a

specific set of region and language combinations.

WrongThread

-----------

Summary: Wrong Thread

Priority: 6 / 10

Severity: Error

Category: Correctness

Ensures that a method which expects to be called on a specific thread, is

actually called from that thread. For example, calls on methods in widgets

should always be made on the UI thread.

More information:

http://developer.android.com/guide/components/processes-and-threads.html#Threads

AppCompatResource

-----------------

Summary: Menu namespace

Priority: 5 / 10

Severity: Error

Category: Correctness

When using the appcompat library, menu resources should refer to the

showAsAction in the app: namespace, not the android: namespace.

Similarly, when not using the appcompat library, you should be using the

android:showAsAction attribute.

AppLinksAutoVerifyError

-----------------------

Summary: App Links Auto Verification Failure

Priority: 5 / 10

Severity: Error

Category: Correctness

NOTE: This issue is disabled by default!

You can enable it by adding --enable AppLinksAutoVerifyError

Ensures that app links are correctly set and associated with website.

More information:

https://g.co/appindexing/applinks

AppLinksAutoVerifyWarning

-------------------------

Summary: Potential App Links Auto Verification Failure

Priority: 5 / 10

Severity: Warning

Category: Correctness

NOTE: This issue is disabled by default!

You can enable it by adding --enable AppLinksAutoVerifyWarning

Ensures that app links are correctly set and associated with website.

More information:

https://g.co/appindexing/applinks

BatteryLife

-----------

Summary: Battery Life Issues

Priority: 5 / 10

Severity: Warning

Category: Correctness

This issue flags code that either

* negatively affects battery life, or

* uses APIs that have recently changed behavior to prevent background tasks

from consuming memory and battery excessively.

Generally, you should be using JobScheduler or GcmNetworkManager instead.

For more details on how to update your code, please

seehttp://developer.android.com/preview/features/background-optimization.html

More information:

http://developer.android.com/preview/features/background-optimization.html

DuplicateActivity

-----------------

Summary: Activity registered more than once

Priority: 5 / 10

Severity: Fatal

Category: Correctness

An activity should only be registered once in the manifest. If it is

accidentally registered more than once, then subtle errors can occur, since

attribute declarations from the two elements are not merged, so you may

accidentally remove previous declarations.

DuplicateUsesFeature

--------------------

Summary: Feature declared more than once

Priority: 5 / 10

Severity: Warning

Category: Correctness

A given feature should only be declared once in the manifest.

FullBackupContent

-----------------

Summary: Valid Full Backup Content File

Priority: 5 / 10

Severity: Fatal

Category: Correctness

Ensures that a <full-backup-content> file, which is pointed to by a

android:fullBackupContent attribute in the manifest file, is valid

More information:

http://android-developers.blogspot.com/2015/07/auto-backup-for-apps-made-simple.html

IncludeLayoutParam

------------------

Summary: Ignored layout params on include

Priority: 5 / 10

Severity: Error

Category: Correctness

Layout parameters specified on an <include> tag will only be used if you also

override layout_width and layout_height on the <include> tag; otherwise they

will be ignored.

More information:

http://stackoverflow.com/questions/2631614/does-android-xml-layouts-include-tag-really-work

InflateParams

-------------

Summary: Layout Inflation without a Parent

Priority: 5 / 10

Severity: Warning

Category: Correctness

When inflating a layout, avoid passing in null as the parent view, since

otherwise any layout parameters on the root of the inflated layout will be

ignored.

More information:

http://www.doubleencore.com/2013/05/layout-inflation-as-intended

LogTagMismatch

--------------

Summary: Mismatched Log Tags

Priority: 5 / 10

Severity: Error

Category: Correctness

When guarding a Log.v(tag, ...) call with Log.isLoggable(tag), the tag passed

to both calls should be the same. Similarly, the level passed in to

Log.isLoggable should typically match the type of Log call, e.g. if checking

level Log.DEBUG, the corresponding Log call should be Log.d, not Log.i.

LongLogTag

----------

Summary: Too Long Log Tags

Priority: 5 / 10

Severity: Error

Category: Correctness

Log tags are only allowed to be at most 23 tag characters long.

ManifestOrder

-------------

Summary: Incorrect order of elements in manifest

Priority: 5 / 10

Severity: Warning

Category: Correctness

The <application> tag should appear after the elements which declare which

version you need, which features you need, which libraries you need, and so

on. In the past there have been subtle bugs (such as themes not getting

applied correctly) when the <application> tag appears before some of these

other elements, so it's best to order your manifest in the logical dependency

order.

ManifestTypo

------------

Summary: Typos in manifest tags

Priority: 5 / 10

Severity: Fatal

Category: Correctness

This check looks through the manifest, and if it finds any tags that look like

likely misspellings, they are flagged.

MissingId

---------

Summary: Fragments should specify an id or tag

Priority: 5 / 10

Severity: Warning

Category: Correctness

If you do not specify an android:id or an android:tag attribute on a

<fragment> element, then if the activity is restarted (for example for an

orientation rotation) you may lose state. From the fragment documentation:

"Each fragment requires a unique identifier that the system can use to restore

the fragment if the activity is restarted (and which you can use to capture

the fragment to perform transactions, such as remove it).

* Supply the android:id attribute with a unique ID.

* Supply the android:tag attribute with a unique string.

If you provide neither of the previous two, the system uses the ID of the

container view.

More information:

http://developer.android.com/guide/components/fragments.html

NetworkSecurityConfig

---------------------

Summary: Valid Network Security Config File

Priority: 5 / 10

Severity: Fatal

Category: Correctness

Ensures that a <network-security-config> file, which is pointed to by an

android:networkSecurityConfig attribute in the manifest file, is valid

More information:

https://developer.android.com/preview/features/security-config.html

NfcTechWhitespace

-----------------

Summary: Whitespace in NFC tech lists

Priority: 5 / 10

Severity: Fatal

Category: Correctness

In a <tech-list>, there can be whitespace around the <tech> elements,but not

inside them. This is because the code which reads in the tech list is

currently very strict and will include the whitespace as part of the name.

In other words, use <tech>name</tech>, not <tech> name </tech>.

More information:

https://code.google.com/p/android/issues/detail?id=65351

ProtectedPermissions

--------------------

Summary: Using system app permission

Priority: 5 / 10

Severity: Error

Category: Correctness

Permissions with the protection level signature or signatureOrSystem are only

granted to system apps. If an app is a regular non-system app, it will never

be able to use these permissions.

SQLiteString

------------

Summary: Using STRING instead of TEXT

Priority: 5 / 10

Severity: Warning

Category: Correctness

In SQLite, any column can store any data type; the declared type for a column

is more of a hint as to what the data should be cast to when stored.

There are many ways to store a string. TEXT, VARCHAR, CHARACTER and CLOB are

string types, but `STRING` is not. Columns defined as STRING are actually

numeric.

If you try to store a value in a numeric column, SQLite will try to cast it to

a float or an integer before storing. If it can't, it will just store it as a

string.

This can lead to some subtle bugs. For example, when SQLite encounters a

string like 1234567e1234, it will parse it as a float, but the result will be

out of range for floating point numbers, so Inf will be stored! Similarly,

strings that look like integers will lose leading zeroes.

To fix this, you can change your schema to use a TEXT type instead.

More information:

https://www.sqlite.org/datatype3.html

StateListReachable

------------------

Summary: Unreachable(不能得到的) state in a <selector>

Priority: 5 / 10

Severity: Warning

Category: Correctness

In a selector, only the last child in the state list should omit a state

qualifier. If not, all subsequent items in the list will be ignored since the

given item will match all.

UnknownIdInLayout

-----------------

Summary: Reference to an id that is not in the current layout

Priority: 5 / 10

Severity: Warning

Category: Correctness

The @+id/ syntax refers to an existing id, or creates a new one if it has not

already been defined elsewhere. However, this means that if you have a typo in

your reference, or if the referred view no longer exists, you do not get a

warning since the id will be created on demand.

This is sometimes intentional(故意的), for example where you are referring to a view

which is provided in a different layout via an include. However, it is usually

an accident where you have a typo or you have renamed a view without updating

all the references to it.

UnlocalizedSms

--------------

Summary: SMS phone number missing country code

Priority: 5 / 10

Severity: Warning

Category: Correctness

SMS destination numbers must start with a country code or the application code

must ensure that the SMS is only sent when the user is in the same country as

the receiver.

ValidRestrictions

-----------------

Summary: Invalid Restrictions Descriptor

Priority: 5 / 10

Severity: Fatal

Category: Correctness

Ensures that an applications restrictions XML file is properly formed

More information:

https://developer.android.com/reference/android/content/RestrictionsManager.html

VectorDrawableCompat

--------------------

Summary: Using VectorDrawableCompat

Priority: 5 / 10

Severity: Error

Category: Correctness

To use VectorDrawableCompat, you need to make two modifications to your

project. First, set android.defaultConfig.vectorDrawables.useSupportLibrary =

true in your build.gradle file, and second, use app:srcCompat instead of

android:src to refer to vector drawables.

More information:

http://chris.banes.me/2016/02/25/appcompat-vector/#enabling-the-flag

VectorRaster

------------

Summary: Vector Image Generation

Priority: 5 / 10

Severity: Warning

Category: Correctness

Vector icons require API 21, but when using Android Gradle plugin 1.4 or

higher, vectors placed in the drawable(可拉的) folder are automatically moved to

drawable-*dpi-v21 and a bitmap image is generated each drawable-*dpi folder

instead, for backwards compatibility (provided minSdkVersion is less than

21.).

However, there are some limitations to this vector image generation, and this

lint check flags elements and attributes that are not fully supported. You

should manually check whether the generated output is acceptable for those

older devices.

GradleDependency

----------------

Summary: Obsolete Gradle Dependency

Priority: 4 / 10

Severity: Warning

Category: Correctness

This detector looks for usages of libraries where the version you are using is

not the current stable release. Using older versions is fine, and there are

cases where you deliberately(故意地) want to stick with an older version. However, you

may simply not be aware that a more recent version is available, and that is

what this lint check helps find.

GradleDynamicVersion

--------------------

Summary: Gradle Dynamic Version

Priority: 4 / 10

Severity: Warning

Category: Correctness

Using + in dependencies lets you automatically pick up the latest available

version rather than a specific, named version. However, this is not

recommended; your builds are not repeatable; you may have tested with a

slightly different version than what the build server used. (Using a dynamic

version as the major version number is more problematic(问题的) than using it in the

minor version position.)

GradleIdeError

--------------

Summary: Gradle IDE Support Issues

Priority: 4 / 10

Severity: Error

Category: Correctness

Gradle is highly flexible, and there are things you can do in Gradle files

which can make it hard or impossible for IDEs to properly handle the project.

This lint check looks for constructs that potentially break IDE support.

GradleOverrides

---------------

Summary: Value overridden(蹂躏) by Gradle build script

Priority: 4 / 10

Severity: Warning

Category: Correctness

The value of (for example) minSdkVersion is only used if it is not specified

in the build.gradle build scripts. When specified in the Gradle build scripts,

the manifest value is ignored and can be misleading, so should be removed to

avoid ambiguity.

GradlePath

----------

Summary: Gradle Path Issues

Priority: 4 / 10

Severity: Warning

Category: Correctness

Gradle build scripts are meant to be cross platform, so file paths use

Unix-style path separators (a forward slash) rather than Windows path

separators (a backslash(反斜杠)). Similarly, to keep projects portable and repeatable,

avoid using absolute paths on the system; keep files within the project

instead. To share code between projects, consider creating an android-library

and an AAR dependency

GridLayout

----------

Summary: GridLayout validation

Priority: 4 / 10

Severity: Fatal

Category: Correctness

Declaring a layout_row or layout_column that falls outside the declared size

of a GridLayout's rowCount or columnCount is usually an unintentional(非故意的) error.

InOrMmUsage

-----------

Summary: Using mm or in dimensions

Priority: 4 / 10

Severity: Warning

Category: Correctness

Avoid using mm (millimeters) or in (inches) as the unit for dimensions.

While it should work in principle, unfortunately many devices do not report

the correct true physical density, which means that the dimension calculations

won't work correctly. You are better off using dp (and for font sizes, sp.)

NewerVersionAvailable

---------------------

Summary: Newer Library Versions Available

Priority: 4 / 10

Severity: Warning

Category: Correctness

NOTE: This issue is disabled by default!

You can enable it by adding --enable NewerVersionAvailable

This detector checks with a central repository to see if there are newer

versions available for the dependencies used by this project. This is similar

to the GradleDependency check, which checks for newer versions available in

the Android SDK tools and libraries, but this works with any MavenCentral

dependency, and connects to the library every time, which makes it more

flexible but also much slower.

ObjectAnimatorBinding

---------------------

Summary: Incorrect ObjectAnimator Property

Priority: 4 / 10

Severity: Error

Category: Correctness

This check cross references properties referenced by String from

ObjectAnimator and PropertyValuesHolder method calls and ensures that the

corresponding setter methods exist and have the right signatures.

RequiredSize

------------

Summary: Missing layout_width or layout_height attributes

Priority: 4 / 10

Severity: Error

Category: Correctness

All views must specify an explicit layout_width and layout_height attribute.

There is a runtime check for this, so if you fail to specify a size, an

exception is thrown at runtime.

It's possible to specify these widths via styles as well. GridLayout, as a

special case, does not require you to specify a size.

RestrictedApi

-------------

Summary: Restricted API

Priority: 4 / 10

Severity: Error

Category: Correctness

This API has been flagged with a restriction that has not been met.

Examples of API restrictions:

* Method can only be invoked by a subclass(亚纲)

* Method can only be accessed from within the same library (defined by the

Gradle library group id)

.* Method can only be accessed from tests.

.

You can add your own API restrictions with the @RestrictTo annotation.

VisibleForTests

---------------

Summary: Visible Only For Tests

Priority: 4 / 10

Severity: Warning

Category: Correctness

With the @VisibleForTesting annotation you can specify an otherwise= attribute

which specifies the intended visibility if the method had not been made more

widely visible for the tests.

This check looks for accesses from production code (e.g. not tests) where the

access would not have been allowed with the intended production visibility.

WrongCase

---------

Summary: Wrong case for view tag

Priority: 4 / 10

Severity: Fatal

Category: Correctness

Most layout tags, such as <Button>, refer to actual view classes and are

therefore capitalized(资本化). However, there are exceptions such as <fragment> and

<include>. This lint check looks for incorrect capitalizations(资本化).

More information:

http://developer.android.com/guide/components/fragments.html

ExtraText

---------

Summary: Extraneous(外来的) text in resource files

Priority: 3 / 10

Severity: Warning

Category: Correctness

Layout resource files should only contain elements and attributes. Any XML

text content found in the file is likely accidental (and potentially dangerous

if the text resembles(类似) XML and the developer believes the text to be

functional)

InnerclassSeparator

-------------------

Summary: Inner classes should use $ rather than .

Priority: 3 / 10

Severity: Warning

Category: Correctness

When you reference an inner class in a manifest file, you must use '$' instead

of '.' as the separator character, i.e. Outer$Inner instead of Outer.Inner.

(If you get this warning for a class which is not actually an inner class,

it's because you are using uppercase(以大写字母印刷) characters in your package name, which is

not conventional.)

LocalSuppress

-------------

Summary: @SuppressLint on invalid element

Priority: 3 / 10

Severity: Error

Category: Correctness

The @SuppressAnnotation is used to suppress Lint warnings in Java files.

However, while many lint checks analyzes the Java source code, where they can

find annotations on (for example) local variables, some checks are analyzing

the .class files. And in class files, annotations only appear on classes,

fields and methods. Annotations placed on local variables disappear. If you

attempt to suppress a lint error for a class-file based lint check, the

suppress annotation not work. You must move the annotation out to the

surrounding method.

ParcelClassLoader

-----------------

Summary: Default Parcel Class Loader

Priority: 3 / 10

Severity: Warning

Category: Correctness

The documentation for Parcel#readParcelable(ClassLoader) (and its variations)

says that you can pass in null to pick up the default class loader. However,

that ClassLoader is a system class loader and is not able to find classes in

your own application.

If you are writing your own classes into the Parcel (not just SDK classes like

String and so on), then you should supply a ClassLoader for your application

instead; a simple way to obtain one is to just call

getClass().getClassLoader() from your own class.

More information:

http://developer.android.com/reference/android/os/Parcel.html

ParcelCreator

-------------

Summary: Missing Parcelable CREATOR field

Priority: 3 / 10

Severity: Error

Category: Correctness

According to the Parcelable interface documentation, "Classes implementing the

Parcelable interface must also have a static field called CREATOR, which is an

object implementing the Parcelable.Creator interface."

More information:

http://developer.android.com/reference/android/os/Parcelable.html

PermissionImpliesUnsupportedHardware

------------------------------------

Summary: Permission Implies Unsupported Hardware

Priority: 3 / 10

Severity: Warning

Category: Correctness

The <uses-permission> element should not require a permission that implies an

unsupported TV hardware feature. Google Play assumes that certain hardware

related permissions indicate that the underlying hardware features are

required by default. To fix the issue, consider declaring the corresponding

uses-feature element with required="false" attribute.

More information:

http://developer.android.com/guide/topics/manifest/uses-feature-element.html#permissions

PrivateResource

---------------

Summary: Using private resources

Priority: 3 / 10

Severity: Warning

Category: Correctness

Private resources should not be referenced; the may not be present everywhere,

and even where they are they may disappear without notice.

To fix this, copy the resource into your own project instead.

ProguardSplit

-------------

Summary: Proguard.cfg file contains generic Android rules

Priority: 3 / 10

Severity: Warning

Category: Correctness

Earlier versions of the Android tools bundled a single proguard.cfg file

containing a ProGuard configuration file suitable for Android shrinking and

obfuscation(困惑). However, that version was copied into new projects, which means

that it does not continue to get updated as we improve the default ProGuard

rules for Android.

In the new version of the tools, we have split the ProGuard configuration into

two halves:

* A simple configuration file containing only project-specific flags, in your

project

* A generic configuration file containing the recommended set of ProGuard

options for Android projects. This generic file lives in the SDK install

directory which means that it gets updated along with the tools.

In order for this to work, the proguard.config property in the

project.properties file now refers to a path, so you can reference both the

generic file as well as your own (and any additional files too).

To migrate your project to the new setup, create a new proguard-project.txt

file in your project containing any project specific ProGuard flags as well as

any customizations(定制) you have made, then update your project.properties file to

contain:

proguard.config=${sdk.dir}/tools/proguard/proguard-android.txt:proguard-projec

.txt

ShiftFlags

----------

Summary: Dangerous Flag Constant Declaration

Priority: 3 / 10

Severity: Warning

Category: Correctness

When defining multiple constants for use in flags, the recommended style is to

use the form 1 << 2, 1 << 3, 1 << 4 and so on to ensure that the constants are

unique and non-overlapping.

SpUsage

-------

Summary: Using dp instead of sp for text sizes

Priority: 3 / 10

Severity: Warning

Category: Correctness

When setting text sizes, you should normally use sp, or "scale-independent

pixels". This is like the dp unit, but it is also scaled by the user's font

size preference. It is recommend you use this unit when specifying font sizes,

so they will be adjusted for both the screen density and the user's

preference.

There are cases where you might need to use dp; typically this happens when

the text is in a container with a specific dp-size. This will prevent the text

from spilling outside the container. Note however that this means that the

user's font size settings are not respected, so consider adjusting the layout

itself to be more flexible.

More information:

http://developer.android.com/training/multiscreen/screendensities.html

SwitchIntDef

------------

Summary: Missing @IntDef in Switch

Priority: 3 / 10

Severity: Warning

Category: Correctness

This check warns if a switch statement does not explicitly include all the

values declared by the typedef @IntDef declaration.

UniqueConstants

---------------

Summary: Overlapping Enumeration Constants

Priority: 3 / 10

Severity: Error

Category: Correctness

The @IntDef annotation allows you to create a light-weight "enum" or type

definition. However, it's possible to accidentally specify the same value for

two or more of the values, which can lead to hard-to-detect bugs. This check

looks for this scenario and flags any repeated constants.

In some cases, the repeated constant is intentional(故意的) (for example, renaming a

constant to a more intuitive name, and leaving the old name in place for

compatibility purposes.) In that case, simply suppress this check by adding a

@SuppressLint("UniqueConstants") annotation.

AccidentalOctal

---------------

Summary: Accidental Octal

Priority: 2 / 10

Severity: Error

Category: Correctness

In Groovy, an integer literal that starts with a leading 0 will be interpreted

as an octal(八进制的) number. That is usually (always?) an accident and can lead to

subtle bugs, for example when used in the versionCode of an app.

Deprecated

----------

Summary: Using deprecated(反对) resources

Priority: 2 / 10

Severity: Warning

Category: Correctness

Deprecated views, attributes and so on are deprecated because there is a

better way to do something. Do it that new way. You've been warned.

MangledCRLF

-----------

Summary: Mangled(乱砍) file line endings

Priority: 2 / 10

Severity: Error

Category: Correctness

NOTE: This issue is disabled by default!

You can enable it by adding --enable MangledCRLF

On Windows, line endings are typically recorded as carriage return plus

newline: 
.

This detector looks for invalid line endings with repeated carriage return

characters (without newlines). Previous versions of the ADT plugin could

accidentally introduce these into the file, and when editing the file, the

editor could produce confusing visual artifacts(史前古器物).

More information:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=375421

MissingVersion

--------------

Summary: Missing application name/version

Priority: 2 / 10

Severity: Warning

Category: Correctness

You should define the version information for your application.

android:versionCode: An integer value that represents the version of the

application code, relative to other versions.

android:versionName: A string value that represents the release version of the

application code, as it should be shown to users.

More information:

http://developer.android.com/tools/publishing/versioning(版本控制).html#appversioning

Orientation

-----------

Summary: Missing explicit orientation

Priority: 2 / 10

Severity: Error

Category: Correctness

The default orientation of a LinearLayout is horizontal. It's pretty easy to

believe that the layout is vertical, add multiple children to it, and wonder

why only the first child is visible (when the subsequent children are off

screen to the right). This lint rule helps pinpoint this issue by warning

whenever a LinearLayout is used with an implicit(含蓄的) orientation and multiple

children.

It also checks for empty LinearLayouts without an orientation attribute that

also defines an id attribute. This catches the scenarios where children will

be added to the LinearLayout dynamically(动力学的).

PxUsage

-------

Summary: Using 'px' dimension

Priority: 2 / 10

Severity: Warning

Category: Correctness

For performance reasons and to keep the code simpler, the Android system uses

pixels as the standard unit for expressing dimension or coordinate values.

That means that the dimensions of a view are always expressed in the code

using pixels, but always based on the current screen density. For instance, if

myView.getWidth() returns 10, the view is 10 pixels wide on the current

screen, but on a device with a higher density screen, the value returned might

be 15. If you use pixel values in your application code to work with bitmaps

that are not pre-scaled for the current screen density, you might need to

scale the pixel values that you use in your code to match the un-scaled bitmap

source.

More information:

http://developer.android.com/guide/practices/screens_support.html#screen-independence

SupportAnnotationUsage

----------------------

Summary: Incorrect support annotation usage

Priority: 2 / 10

Severity: Error

Category: Correctness

This lint check makes sure that the support annotations (such as @IntDef and

@ColorInt) are used correctly. For example, it's an error to specify an

@IntRange where the from value is higher than the to value.

Correctness:Messages

====================

StringFormatInvalid

-------------------

Summary: Invalid format string

Priority: 9 / 10

Severity: Error

Category: Correctness:Messages

If a string contains a '%' character, then the string may be a formatting

string which will be passed to String.format from Java code to replace each

'%' occurrence with specific values.

This lint warning checks for two related problems:

(1) Formatting strings that are invalid, meaning that String.format will throw

exceptions at runtime when attempting to use the format string.

(2) Strings containing '%' that are not formatting strings getting passed to a

String.format call. In this case the '%' will need to be escaped as '%%'.

NOTE: Not all Strings which look like formatting strings are intended for use

by String.format; for example, they may contain date formats intended for

android.text.format.Time#format(). Lint cannot always figure out that a String

is a date format, so you may get false warnings in those scenarios. See the

suppress help topic for information on how to suppress errors in that case.

StringFormatMatches

-------------------

Summary: String.format string doesn't match the XML format string

Priority: 9 / 10

Severity: Error

Category: Correctness:Messages

This lint check ensures the following:

(1) If there are multiple translations of the format string, then all

translations use the same type for the same numbered arguments

(2) The usage of the format string in Java is consistent with the format

string, meaning that the parameter types passed to String.format matches those

in the format string.

MissingQuantity

---------------

Summary: Missing quantity translation

Priority: 8 / 10

Severity: Error

Category: Correctness:Messages

Different languages have different rules for grammatical agreement with

quantity. In English, for example, the quantity 1 is a special case. We write

"1 book", but for any other quantity we'd write "n books". This distinction

between singular and plural is very common, but other languages make finer

distinctions.

This lint check looks at each translation of a <plural> and makes sure that

all the quantity strings considered by the given language are provided by this

translation.

For example, an English translation must provide a string for quantity="one".

Similarly, a Czech translation must provide a string for quantity="few".

More information:

http://developer.android.com/guide/topics/resources/string-resource.html#Plurals

MissingTranslation

------------------

Summary: Incomplete translation

Priority: 8 / 10

Severity: Fatal

Category: Correctness:Messages

If an application has more than one locale, then all the strings declared in

one language should also be translated in all other languages.

If the string should not be translated, you can add the attribute

translatable="false" on the <string> element, or you can define all your

non-translatable strings in a resource file called donottranslate.xml. Or, you

can ignore the issue with a tools:ignore="MissingTranslation" attribute.

By default this detector allows regions of a language to just provide a subset

of the strings and fall back to the standard language strings. You can require

all regions to provide a full translation by setting the environment variable

ANDROID_LINT_COMPLETE_REGIONS.

You can tell lint (and other tools) which language is the default language in

your res/values/ folder by specifying tools:locale="languageCode" for the root

<resources> element in your resource file. (The tools prefix refers to the

namespace declaration http://schemas.android.com/tools.)

Typos

-----

Summary: Spelling error

Priority: 7 / 10

Severity: Warning

Category: Correctness:Messages

This check looks through the string definitions, and if it finds any words

that look like likely misspellings, they are flagged.

ExtraTranslation

----------------

Summary: Extra translation

Priority: 6 / 10

Severity: Fatal

Category: Correctness:Messages

If a string appears in a specific language translation file, but there is no

corresponding string in the default locale, then this string is probably

unused. (It's technically possible that your application is only intended to

run in a specific locale, but it's still a good idea to provide a fallback.).

Note that these strings can lead to crashes if the string is looked up on any

locale not providing a translation, so it's important to clean them up.

ImpliedQuantity

---------------

Summary: Implied Quantities

Priority: 5 / 10

Severity: Error

Category: Correctness:Messages

Plural strings should generally include a %s or %d formatting argument. In

locales like English, the one quantity only applies to a single value, 1, but

that's not true everywhere. For example, in Slovene, the one quantity will

apply to 1, 101, 201, 301, and so on. Similarly, there are locales where

multiple values match the zero and two quantities.

In these locales, it is usually an error to have a message which does not

include a formatting argument (such as '%d'), since it will not be clear from

the grammar what quantity the quantity string is describing.

More information:

http://developer.android.com/guide/topics/resources/string-resource.html#Plurals

PluralsCandidate

----------------

Summary: Potential Plurals

Priority: 5 / 10

Severity: Warning

Category: Correctness:Messages

This lint check looks for potential errors in internationalization where you

have translated a message which involves a quantity and it looks like other

parts of the string may need grammatical changes.

For example, rather than something like this:

<string name="try_again">Try again in %d seconds.</string>

you should be using a plural:

<plurals name="try_again">

<item quantity="one">Try again in %d second</item>

<item quantity="other">Try again in %d seconds</item>

</plurals>

This will ensure that in other languages the right set of translations are

provided for the different quantity classes.

(This check depends on some heuristics, so it may not accurately determine

whether a string really should be a quantity. You can use tools:ignore to

filter out false positives.

More information:

http://developer.android.com/guide/topics/resources/string-resource.html#Plurals

StringFormatCount

-----------------

Summary: Formatting argument types incomplete or inconsistent

Priority: 5 / 10

Severity: Warning

Category: Correctness:Messages

When a formatted string takes arguments, it usually needs to reference the

same arguments in all translations (or all arguments if there are no

translations.

There are cases where this is not the case, so this issue is a warning rather

than an error by default. However, this usually happens when a language is not

translated or updated correctly.

UnusedQuantity

--------------

Summary: Unused quantity translations

Priority: 3 / 10

Severity: Warning

Category: Correctness:Messages

Android defines a number of different quantity strings, such as zero, one, few

and many. However, many languages do not distinguish grammatically between all

these different quantities.

This lint check looks at the quantity strings defined for each translation and

flags any quantity strings that are unused (because the language does not make

that quantity distinction, and Android will therefore not look it up.).

For example, in Chinese, only the other quantity is used, so even if you

provide translations for zero and one, these strings will not be returned when

getQuantityString() is called, even with 0 or 1.

More information:

http://developer.android.com/guide/topics/resources/string-resource.html#Plurals

Security

========

AddJavascriptInterface

----------------------

Summary: addJavascriptInterface Called

Priority: 9 / 10

Severity: Warning

Category: Security

For applications built for API levels below 17, WebView#addJavascriptInterface

presents a security hazard as JavaScript on the target web page has the

ability to use reflection to access the injected object's public fields and

thus manipulate the host application in unintended ways.

More information:

https://labs.mwrinfosecurity.com/blog/2013/09/24/webview-addjavascriptinterface-remote-code-execution/

GetInstance

-----------

Summary: Cipher.getInstance with ECB

Priority: 9 / 10

Severity: Warning

Category: Security

Cipher#getInstance should not be called with ECB as the cipher mode or without

setting the cipher mode because the default mode on android is ECB, which is

insecure.

SecureRandom

------------

Summary: Using a fixed seed with SecureRandom

Priority: 9 / 10

Severity: Warning

Category: Security

Specifying a fixed seed will cause the instance to return a predictable

sequence of numbers. This may be useful for testing but it is not appropriate

for secure use.

More information:

http://developer.android.com/reference/java/security/SecureRandom.html

TrulyRandom

-----------

Summary: Weak RNG

Priority: 9 / 10

Severity: Warning

Category: Security

Key generation, signing, encryption, and random number generation may not

receive cryptographically strong values due to improper initialization of the

underlying PRNG on Android 4.3 and below.

If your application relies on cryptographically secure random number

generation you should apply the workaround described in

https://android-developers.blogspot.com/2013/08/some-securerandom-thoughts.htm

.

This lint rule is mostly informational; it does not accurately detect whether

cryptographically secure RNG is required, or whether the workaround has

already been applied. After reading the blog entry and updating your code if

necessary, you can disable this lint issue.

More information:

https://android-developers.blogspot.com/2013/08/some-securerandom-thoughts.html

VulnerableCordovaVersion

------------------------

Summary: Vulnerable Cordova Version

Priority: 9 / 10

Severity: Warning

Category: Security

The version of Cordova used in the app is vulnerable to security issues.

Please update to the latest Apache Cordova version.

More information:

https://cordova.apache.org/announcements/2015/11/20/security.html

ExportedPreferenceActivity

--------------------------

Summary: PreferenceActivity should not be exported

Priority: 8 / 10

Severity: Warning

Category: Security

Fragment injection gives anyone who can send your PreferenceActivity an intent

the ability to load any fragment, with any arguments, in your process.

More information:

http://securityintelligence.com/new-vulnerability-android-framework-fragment-injection

JavascriptInterface

-------------------

Summary: Missing @JavascriptInterface on methods

Priority: 8 / 10

Severity: Error

Category: Security

As of API 17, you must annotate methods in objects registered with the

addJavascriptInterface method with a @JavascriptInterface annotation.

More information:

http://developer.android.com/reference/android/webkit/WebView.html#addJavascriptInterface(java.lang.Object, java.lang.String)

PackageManagerGetSignatures

---------------------------

Summary: Potential Multiple Certificate Exploit

Priority: 8 / 10

Severity: Information

Category: Security

Improper validation of app signatures could lead to issues where a malicious

app submits itself to the Play Store with both its real certificate and a fake

certificate and gains access to functionality or information it shouldn't have

due to another application only checking for the fake certificate and ignoring

the rest. Please make sure to validate all signatures returned by this

method.

More information:

https://bluebox.com/technical/android-fake-id-vulnerability/

PackagedPrivateKey

------------------

Summary: Packaged private key

Priority: 8 / 10

Severity: Fatal

Category: Security

In general, you should not package private key files inside your app.

GrantAllUris

------------

Summary: Content provider shares everything

Priority: 7 / 10

Severity: Warning

Category: Security

The <grant-uri-permission> element allows specific paths to be shared. This

detector checks for a path URL of just '/' (everything), which is probably not

what you want; you should limit access to a subset.

AllowAllHostnameVerifier

------------------------

Summary: Insecure HostnameVerifier

Priority: 6 / 10

Severity: Warning

Category: Security

This check looks for use of HostnameVerifier implementations whose verify

method always returns true (thus trusting any hostname) which could result in

insecure network traffic caused by trusting arbitrary hostnames in TLS/SSL

certificates presented by peers.

AuthLeak

--------

Summary: Code might contain an auth leak

Priority: 6 / 10

Severity: Warning

Category: Security

Strings in java apps can be discovered by decompiling apps, this lint check

looks for code which looks like it may contain an url with a username and

password

BadHostnameVerifier

-------------------

Summary: Insecure HostnameVerifier

Priority: 6 / 10

Severity: Warning

Category: Security

This check looks for implementations of HostnameVerifier whose verify method

always returns true (thus trusting any hostname) which could result in

insecure network traffic caused by trusting arbitrary hostnames in TLS/SSL

certificates presented by peers.

EasterEgg

---------

Summary: Code contains easter egg

Priority: 6 / 10

Severity: Warning

Category: Security

NOTE: This issue is disabled by default!

You can enable it by adding --enable EasterEgg

An "easter egg" is code deliberately hidden in the code, both from potential

users and even from other developers. This lint check looks for code which

looks like it may be hidden from sight.

HardwareIds

-----------

Summary: Hardware Id Usage

Priority: 6 / 10

Severity: Warning

Category: Security

Using device identifiers is not recommended other than for high value fraud

prevention and advanced telephony use-cases. For advertising use-cases, use

AdvertisingIdClient$Info#getId and for analytics, use InstanceId#getId.

More information:

https://developer.android.com/training/articles/user-data-ids.html

SSLCertificateSocketFactoryCreateSocket

---------------------------------------

Summary: Insecure call to SSLCertificateSocketFactory.createSocket()

Priority: 6 / 10

Severity: Warning

Category: Security

When SSLCertificateSocketFactory.createSocket() is called with an InetAddress

as the first parameter, TLS/SSL hostname verification is not performed, which

could result in insecure network traffic caused by trusting arbitrary

hostnames in TLS/SSL certificates presented by peers. In this case, developers

must ensure that the InetAddress is explicitly verified against the

certificate through other means, such as by calling

`SSLCertificateSocketFactory.getDefaultHostnameVerifier() to get a

HostnameVerifier and calling HostnameVerifier.verify().

SSLCertificateSocketFactoryGetInsecure

--------------------------------------

Summary: Call to SSLCertificateSocketFactory.getInsecure()

Priority: 6 / 10

Severity: Warning

Category: Security

The SSLCertificateSocketFactory.getInsecure() method returns an

SSLSocketFactory with all TLS/SSL security checks disabled, which could result

in insecure network traffic caused by trusting arbitrary TLS/SSL certificates

presented by peers. This method should be avoided unless needed for a special

circumstance such as debugging. Instead,

SSLCertificateSocketFactory.getDefault() should be used.

SetJavaScriptEnabled

--------------------

Summary: Using setJavaScriptEnabled

Priority: 6 / 10

Severity: Warning

Category: Security

Your code should not invoke setJavaScriptEnabled if you are not sure that your

app really requires JavaScript support.

More information:

http://developer.android.com/guide/practices/security.html

SetWorldReadable

----------------

Summary: File.setReadable() used to make file world-readable

Priority: 6 / 10

Severity: Warning

Category: Security

Setting files world-readable is very dangerous, and likely to cause security

holes in applications. It is strongly discouraged; instead, applications

should use more formal mechanisms for interactions such as ContentProvider,

BroadcastReceiver, and Service.

SetWorldWritable

----------------

Summary: File.setWritable() used to make file world-writable

Priority: 6 / 10

Severity: Warning

Category: Security

Setting files world-writable is very dangerous, and likely to cause security

holes in applications. It is strongly discouraged; instead, applications

should use more formal mechanisms for interactions such as ContentProvider,

BroadcastReceiver, and Service.

TrustAllX509TrustManager

------------------------

Summary: Insecure TLS/SSL trust manager

Priority: 6 / 10

Severity: Warning

Category: Security

This check looks for X509TrustManager implementations whose checkServerTrusted

or checkClientTrusted methods do nothing (thus trusting any certificate chain)

which could result in insecure network traffic caused by trusting arbitrary

TLS/SSL certificates presented by peers.

UnprotectedSMSBroadcastReceiver

-------------------------------

Summary: Unprotected SMS BroadcastReceiver

Priority: 6 / 10

Severity: Warning

Category: Security

BroadcastReceivers that declare an intent-filter for SMS_DELIVER or

SMS_RECEIVED must ensure that the caller has the BROADCAST_SMS permission,

otherwise it is possible for malicious actors to spoof intents.

UnsafeProtectedBroadcastReceiver

--------------------------------

Summary: Unsafe Protected BroadcastReceiver

Priority: 6 / 10

Severity: Warning

Category: Security

BroadcastReceivers that declare an intent-filter for a protected-broadcast

action string must check that the received intent's action string matches the

expected value, otherwise it is possible for malicious actors to spoof

intents.

UseCheckPermission

------------------

Summary: Using the result of check permission calls

Priority: 6 / 10

Severity: Warning

Category: Security

You normally want to use the result of checking a permission; these methods

return whether the permission is held; they do not throw an error if the

permission is not granted. Code which does not do anything with the return

value probably meant to be calling the enforce methods instead, e.g. rather

than Context#checkCallingPermission it should call

Context#enforceCallingPermission.

UsingHttp

---------

Summary: Using HTTP instead of HTTPS

Priority: 6 / 10

Severity: Warning

Category: Security

The Gradle Wrapper is available both via HTTP and HTTPS. HTTPS is more secure

since it protects against man-in-the-middle attacks etc. Older projects

created in Android Studio used HTTP but we now default to HTTPS and recommend

upgrading existing projects.

WrongConstant

-------------

Summary: Incorrect constant

Priority: 6 / 10

Severity: Error

Category: Security

Ensures that when parameter in a method only allows a specific set of

constants, calls obey those rules.

ExportedContentProvider

-----------------------

Summary: Content provider does not require permission

Priority: 5 / 10

Severity: Warning

Category: Security

Content providers are exported by default and any application on the system

can potentially use them to read and write data. If the content provider

provides access to sensitive data, it should be protected by specifying

export=false in the manifest or by protecting it with a permission that can be

granted to other applications.

ExportedReceiver

----------------

Summary: Receiver does not require permission

Priority: 5 / 10

Severity: Warning

Category: Security

Exported receivers (receivers which either set exported=true or contain an

intent-filter and do not specify exported=false) should define a permission

that an entity must have in order to launch the receiver or bind to it.

Without this, any application can use this receiver.

ExportedService

---------------

Summary: Exported service does not require permission

Priority: 5 / 10

Severity: Warning

Category: Security

Exported services (services which either set exported=true or contain an

intent-filter and do not specify exported=false) should define a permission

that an entity must have in order to launch the service or bind to it. Without

this, any application can use this service.

HardcodedDebugMode

------------------

Summary: Hardcoded value of android:debuggable in the manifest

Priority: 5 / 10

Severity: Fatal

Category: Security

It's best to leave out the android:debuggable attribute from the manifest. If

you do, then the tools will automatically insert android:debuggable=true when

building an APK to debug on an emulator or device. And when you perform a

release build, such as Exporting APK, it will automatically set it to false.

If on the other hand you specify a specific value in the manifest file, then

the tools will always use it. This can lead to accidentally publishing your

app with debug information.

InvalidPermission

-----------------

Summary: Invalid Permission Attribute

Priority: 5 / 10

Severity: Error

Category: Security

Not all elements support the permission attribute. If a permission is set on

an invalid element, it is a no-op and ignored. Ensure that this permission

attribute was set on the correct element to protect the correct component.

SignatureOrSystemPermissions

----------------------------

Summary: signatureOrSystem permissions declared

Priority: 5 / 10

Severity: Warning

Category: Security

The signature protection level should probably be sufficient for most needs

and works regardless of where applications are installed. The

signatureOrSystem level is used for certain situations where multiple vendors

have applications built into a system image and need to share specific

features explicitly because they are being built together.

UnsafeDynamicallyLoadedCode

---------------------------

Summary: load used to dynamically load code

Priority: 4 / 10

Severity: Warning

Category: Security

Dynamically loading code from locations other than the application's library

directory or the Android platform's built-in library directories is dangerous,

as there is an increased risk that the code could have been tampered with.

Applications should use loadLibrary when possible, which provides increased

assurance that libraries are loaded from one of these safer locations.

Application developers should use the features of their development

environment to place application native libraries into the lib directory of

their compiled APKs.

UnsafeNativeCodeLocation

------------------------

Summary: Native code outside library directory

Priority: 4 / 10

Severity: Warning

Category: Security

In general, application native code should only be placed in the application's

library directory, not in other locations such as the res or assets

directories. Placing the code in the library directory provides increased

assurance that the code will not be tampered with after application

installation. Application developers should use the features of their

development environment to place application native libraries into the lib

directory of their compiled APKs. Embedding non-shared library native

executables into applications should be avoided when possible.

WorldReadableFiles

------------------

Summary: openFileOutput() or similar call passing MODE_WORLD_READABLE

Priority: 4 / 10

Severity: Warning

Category: Security

There are cases where it is appropriate for an application to write world

readable files, but these should be reviewed carefully to ensure that they

contain no private data that is leaked to other applications.

WorldWriteableFiles

-------------------

Summary: openFileOutput() or similar call passing MODE_WORLD_WRITEABLE

Priority: 4 / 10

Severity: Warning

Category: Security

There are cases where it is appropriate for an application to write world

writeable files, but these should be reviewed carefully to ensure that they

contain no private data, and that if the file is modified by a malicious

application it does not trick or compromise your application.

AllowBackup

-----------

Summary: AllowBackup/FullBackupContent Problems

Priority: 3 / 10

Severity: Warning

Category: Security

The allowBackup attribute determines if an application's data can be backed up

and restored. It is documented at

http://developer.android.com/reference/android/R.attr.html#allowBackup

By default, this flag is set to true. When this flag is set to true,

application data can be backed up and restored by the user using adb backup

and adb restore.

This may have security consequences for an application. adb backup allows

users who have enabled USB debugging to copy application data off of the

device. Once backed up, all application data can be read by the user. adb

restore allows creation of application data from a source specified by the

user. Following a restore, applications should not assume that the data, file

permissions, and directory permissions were created by the application

itself.

Setting allowBackup="false" opts an application out of both backup and

restore.

To fix this warning, decide whether your application should support backup,

and explicitly set android:allowBackup=(true|false)".

If not set to false, and if targeting API 23 or later, lint will also warn

that you should set android:fullBackupContent to configure auto backup.

More information:

https://developer.android.com/training/backup/autosyncapi.html

http://developer.android.com/reference/android/R.attr.html#allowBackup

Performance

===========

DrawAllocation

--------------

Summary: Memory allocations within drawing code

Priority: 9 / 10

Severity: Warning

Category: Performance

You should avoid allocating objects during a drawing or layout operation.

These are called frequently, so a smooth UI can be interrupted by garbage

collection pauses caused by the object allocations.

The way this is generally handled is to allocate the needed objects up front

and to reuse them for each drawing operation.

Some methods allocate memory on your behalf (such as Bitmap.create), and these

should be handled in the same way.

Wakelock

--------

Summary: Incorrect WakeLock usage

Priority: 9 / 10

Severity: Warning

Category: Performance

Failing to release a wakelock properly can keep the Android device in a high

power mode, which reduces battery life. There are several causes of this, such

as releasing the wake lock in onDestroy() instead of in onPause(), failing to

call release() in all possible code paths after an acquire(), and so on.

NOTE: If you are using the lock just to keep the screen on, you should

strongly consider using FLAG_KEEP_SCREEN_ON instead. This window flag will be

correctly managed by the platform as the user moves between applications and

doesn't require a special permission. See

http://developer.android.com/reference/android/view/WindowManager.LayoutParams

html#FLAG_KEEP_SCREEN_ON.

Recycle

-------

Summary: Missing recycle() calls

Priority: 7 / 10

Severity: Warning

Category: Performance

Many resources, such as TypedArrays, VelocityTrackers, etc., should be

recycled (with a recycle() call) after use. This lint check looks for missing

recycle() calls.

ObsoleteLayoutParam

-------------------

Summary: Obsolete layout params

Priority: 6 / 10

Severity: Warning

Category: Performance

The given layout_param is not defined for the given layout, meaning it has no

effect. This usually happens when you change the parent layout or move view

code around without updating the layout params. This will cause useless

attribute processing at runtime, and is misleading for others reading the

layout so the parameter should be removed.

ObsoleteSdkInt

--------------

Summary: Obsolete SDK_INT Version Check

Priority: 6 / 10

Severity: Warning

Category: Performance

This check flags version checks that are not necessary, because the

minSdkVersion (or surrounding known API level) is already at least as high as

the version checked for.

StaticFieldLeak

---------------

Summary: Static Field Leaks

Priority: 6 / 10

Severity: Warning

Category: Performance

A static field will leak contexts.

UseCompoundDrawables

--------------------

Summary: Node can be replaced by a TextView with compound drawables

Priority: 6 / 10

Severity: Warning

Category: Performance

A LinearLayout which contains an ImageView and a TextView can be more

efficiently handled as a compound drawable (a single TextView, using the

drawableTop, drawableLeft, drawableRight and/or drawableBottom attributes to

draw one or more images adjacent to the text).

If the two widgets are offset from each other with margins, this can be

replaced with a drawablePadding attribute.

There's a lint quickfix to perform this conversion in the Eclipse plugin.

ViewTag

-------

Summary: Tagged object leaks

Priority: 6 / 10

Severity: Warning

Category: Performance

Prior to Android 4.0, the implementation of View.setTag(int, Object) would

store the objects in a static map, where the values were strongly referenced.

This means that if the object contains any references pointing back to the

context, the context (which points to pretty much everything else) will leak.

If you pass a view, the view provides a reference to the context that created

it. Similarly, view holders typically contain a view, and cursors are

sometimes also associated with views.

WearableBindListener

--------------------

Summary: Usage of Android Wear BIND_LISTENER is deprecated

Priority: 6 / 10

Severity: Fatal

Category: Performance

BIND_LISTENER receives all Android Wear events whether the application needs

them or not. This can be inefficient and cause applications to wake up

unnecessarily. With Google Play Services 8.2.0 or later it is recommended to

use a more efficient combination of manifest listeners and api-based live

listeners filtered by action, path and/or path prefix.

More information:

http://tools.android.com/tech-docs/bind-listener

LogConditional

--------------

Summary: Unconditional Logging Calls

Priority: 5 / 10

Severity: Warning

Category: Performance

NOTE: This issue is disabled by default!

You can enable it by adding --enable LogConditional

The BuildConfig class (available in Tools 17) provides a constant, "DEBUG",

which indicates whether the code is being built in release mode or in debug

mode. In release mode, you typically want to strip out all the logging calls.

Since the compiler will automatically remove all code which is inside a "if

(false)" check, surrounding your logging calls with a check for

BuildConfig.DEBUG is a good idea.

If you really intend for the logging to be present in release mode, you can

suppress this warning with a @SuppressLint annotation for the intentional

logging calls.

ViewHolder

----------

Summary: View Holder Candidates

Priority: 5 / 10

Severity: Warning

Category: Performance

When implementing a view Adapter, you should avoid unconditionally inflating a

new layout; if an available item is passed in for reuse, you should try to use

that one instead. This helps make for example ListView scrolling much

smoother.

More information:

http://developer.android.com/training/improving-layouts/smooth-scrolling.html#ViewHolder

AnimatorKeep

------------

Summary: Missing @Keep for Animated Properties

Priority: 4 / 10

Severity: Warning

Category: Performance

When you use property animators, properties can be accessed via reflection.

Those methods should be annotated with @Keep to ensure that during release

builds, the methods are not potentially treated as unused and removed, or

treated as internal only and get renamed to something shorter.

This check will also flag other potential reflection problems it encounters,

such as a missing property, wrong argument types, etc.

DuplicateDivider

----------------

Summary: Unnecessary Divider Copy

Priority: 4 / 10

Severity: Warning

Category: Performance

Older versions of the RecyclerView library did not include a divider

decorator, but one was provided as a sample in the support demos. This divider

class has been widely copy/pasted into various projects.

In recent versions of the support library, the divider decorator is now

included, so you can replace custom copies with the "built-in" version,

android.support.v7.widget.DividerItemDecoration.

FieldGetter

-----------

Summary: Using getter instead of field

Priority: 4 / 10

Severity: Warning

Category: Performance

NOTE: This issue is disabled by default!

You can enable it by adding --enable FieldGetter

Accessing a field within the class that defines a getter for that field is at

least 3 times faster than calling the getter. For simple getters that do

nothing other than return the field, you might want to just reference the

local field directly instead.

NOTE: As of Android 2.3 (Gingerbread), this optimization is performed

automatically by Dalvik, so there is no need to change your code; this is only

relevant if you are targeting older versions of Android.

More information:

http://developer.android.com/guide/practices/design/performance.html#internal_get_set

HandlerLeak

-----------

Summary: Handler reference leaks

Priority: 4 / 10

Severity: Warning

Category: Performance

Since this Handler is declared as an inner class, it may prevent the outer

class from being garbage collected. If the Handler is using a Looper or

MessageQueue for a thread other than the main thread, then there is no issue.

If the Handler is using the Looper or MessageQueue of the main thread, you

need to fix your Handler declaration, as follows: Declare the Handler as a

static class; In the outer class, instantiate a WeakReference to the outer

class and pass this object to your Handler when you instantiate the Handler;

Make all references to members of the outer class using the WeakReference

object.

MergeRootFrame

--------------

Summary: FrameLayout can be replaced with <merge> tag

Priority: 4 / 10

Severity: Warning

Category: Performance

If a <FrameLayout> is the root of a layout and does not provide background or

padding etc, it can often be replaced with a <merge> tag which is slightly

more efficient. Note that this depends on context, so make sure you understand

how the <merge> tag works before proceeding.

More information:

http://android-developers.blogspot.com/2009/03/android-layout-tricks-3-optimize-by.html

UseOfBundledGooglePlayServices

------------------------------

Summary: Use of bundled version of Google Play services

Priority: 4 / 10

Severity: Warning

Category: Performance

Google Play services SDK's can be selectively included, which enables a

smaller APK size. Consider declaring dependencies on individual Google Play

services SDK's. If you are using Firebase API's

(http://firebase.google.com/docs/android/setup), Android Studio's Tools u2192

Firebase assistant window can automatically add just the dependencies needed

for each feature.

More information:

http://developers.google.com/android/guides/setup#split

UseSparseArrays

---------------

Summary: HashMap can be replaced with SparseArray

Priority: 4 / 10

Severity: Warning

Category: Performance

For maps where the keys are of type integer, it's typically more efficient to

use the Android SparseArray API. This check identifies scenarios where you

might want to consider using SparseArray instead of HashMap for better

performance.

This is particularly useful when the value types are primitives like ints,

where you can use SparseIntArray and avoid auto-boxing the values from int to

Integer.

If you need to construct a HashMap because you need to call an API outside of

your control which requires a Map, you can suppress this warning using for

example the @SuppressLint annotation.

UseValueOf

----------

Summary: Should use valueOf instead of new

Priority: 4 / 10

Severity: Warning

Category: Performance

You should not call the constructor for wrapper classes directly, such as`new

Integer(42)`. Instead, call the valueOf factory method, such as

Integer.valueOf(42). This will typically use less memory because common

integers such as 0 and 1 will share a single instance.

DisableBaselineAlignment

------------------------

Summary: Missing baselineAligned attribute

Priority: 3 / 10

Severity: Warning

Category: Performance

When a LinearLayout is used to distribute the space proportionally between

nested layouts, the baseline alignment property should be turned off to make

the layout computation faster.

FloatMath

---------

Summary: Using FloatMath instead of Math

Priority: 3 / 10

Severity: Warning

Category: Performance

In older versions of Android, using android.util.FloatMath was recommended for

performance reasons when operating on floats. However, on modern hardware

doubles are just as fast as float (though they take more memory), and in

recent versions of Android, FloatMath is actually slower than using

java.lang.Math due to the way the JIT optimizes java.lang.Math. Therefore, you

should use Math instead of FloatMath if you are only targeting Froyo and

above.

More information:

http://developer.android.com/guide/practices/design/performance.html#avoidfloat

InefficientWeight

-----------------

Summary: Inefficient layout weight

Priority: 3 / 10

Severity: Warning

Category: Performance

When only a single widget in a LinearLayout defines a weight, it is more

efficient to assign a width/height of 0dp to it since it will absorb all the

remaining space anyway. With a declared width/height of 0dp it does not have

to measure its own size first.

NestedWeights

-------------

Summary: Nested layout weights

Priority: 3 / 10

Severity: Warning

Category: Performance

Layout weights require a widget to be measured twice. When a LinearLayout with

non-zero weights is nested inside another LinearLayout with non-zero weights,

then the number of measurements increase exponentially.

Overdraw

--------

Summary: Overdraw: Painting regions more than once

Priority: 3 / 10

Severity: Warning

Category: Performance

If you set a background drawable on a root view, then you should use a custom

theme where the theme background is null. Otherwise, the theme background will

be painted first, only to have your custom background completely cover it;

this is called "overdraw".

NOTE: This detector relies on figuring out which layouts are associated with

which activities based on scanning the Java code, and it's currently doing

that using an inexact pattern matching algorithm. Therefore, it can

incorrectly conclude which activity the layout is associated with and then

wrongly complain that a background-theme is hidden.

If you want your custom background on multiple pages, then you should consider

making a custom theme with your custom background and just using that theme

instead of a root element background.

Of course it's possible that your custom drawable is translucent and you want

it to be mixed with the background. However, you will get better performance

if you pre-mix the background with your drawable and use that resulting image

or color as a custom theme background instead.

UnusedResources

---------------

Summary: Unused resources

Priority: 3 / 10

Severity: Warning

Category: Performance

Unused resources make applications larger and slow down builds.

UselessLeaf

-----------

Summary: Useless leaf layout

Priority: 2 / 10

Severity: Warning

Category: Performance

A layout that has no children or no background can often be removed (since it

is invisible) for a flatter and more efficient layout hierarchy.

UselessParent

-------------

Summary: Useless parent layout

Priority: 2 / 10

Severity: Warning

Category: Performance

A layout with children that has no siblings, is not a scrollview or a root

layout, and does not have a background, can be removed and have its children

moved directly into the parent for a flatter and more efficient layout

hierarchy.

TooDeepLayout

-------------

Summary: Layout hierarchy is too deep

Priority: 1 / 10

Severity: Warning

Category: Performance

Layouts with too much nesting is bad for performance. Consider using a flatter

layout (such as RelativeLayout or GridLayout).The default maximum depth is 10

but can be configured with the environment variable ANDROID_LINT_MAX_DEPTH.

TooManyViews

------------

Summary: Layout has too many views

Priority: 1 / 10

Severity: Warning

Category: Performance

Using too many views in a single layout is bad for performance. Consider using

compound drawables or other tricks for reducing the number of views in this

layout.

The maximum view count defaults to 80 but can be configured with the

environment variable ANDROID_LINT_MAX_VIEW_COUNT.

UnusedIds

---------

Summary: Unused id

Priority: 1 / 10

Severity: Warning

Category: Performance

NOTE: This issue is disabled by default!

You can enable it by adding --enable UnusedIds

This resource id definition appears not to be needed since it is not

referenced from anywhere. Having id definitions, even if unused, is not

necessarily a bad idea since they make working on layouts and menus easier, so

there is not a strong reason to delete these.

UnusedNamespace

---------------

Summary: Unused namespace

Priority: 1 / 10

Severity: Warning

Category: Performance

Unused namespace declarations take up space and require processing that is not

necessary

Usability:Typography

====================

AllCaps

-------

Summary: Combining textAllCaps and markup

Priority: 8 / 10

Severity: Warning

Category: Usability:Typography

The textAllCaps text transform will end up calling toString on the

CharSequence, which has the net effect of removing any markup such as <b>.

This check looks for usages of strings containing markup that also specify

textAllCaps=true.

TypographyDashes

----------------

Summary: Hyphen can be replaced with dash

Priority: 5 / 10

Severity: Warning

Category: Usability:Typography

The "n dash" (–, –) and the "m dash" (—, —) characters are used

for ranges (n dash) and breaks (m dash). Using these instead of plain hyphens

can make text easier to read and your application will look more polished.

More information:

http://en.wikipedia.org/wiki/Dash

TypographyEllipsis

------------------

Summary: Ellipsis string can be replaced with ellipsis character

Priority: 5 / 10

Severity: Warning

Category: Usability:Typography

You can replace the string "..." with a dedicated ellipsis character, ellipsis

character (…, …). This can help make the text more readable.

More information:

http://en.wikipedia.org/wiki/Ellipsis

TypographyFractions

-------------------

Summary: Fraction string can be replaced with fraction character

Priority: 5 / 10

Severity: Warning

Category: Usability:Typography

You can replace certain strings, such as 1/2, and 1/4, with dedicated

characters for these, such as ½ (½) and ¼ (¼). This can help make

the text more readable.

More information:

http://en.wikipedia.org/wiki/Number_Forms

TypographyQuotes

----------------

Summary: Straight quotes can be replaced with curvy quotes

Priority: 5 / 10

Severity: Warning

Category: Usability:Typography

NOTE: This issue is disabled by default!

You can enable it by adding --enable TypographyQuotes

Straight single quotes and double quotes, when used as a pair, can be replaced

by "curvy quotes" (or directional quotes). This can make the text more

readable.

Note that you should never use grave accents and apostrophes to quote, `like

this'.

(Also note that you should not use curvy quotes for code fragments.)

More information:

http://en.wikipedia.org/wiki/Quotation_mark

TypographyOther

---------------

Summary: Other typographical problems

Priority: 3 / 10

Severity: Warning

Category: Usability:Typography

This check looks for miscellaneous typographical problems and offers

replacement sequences that will make the text easier to read and your

application more polished.

Usability:Icons

===============

IconNoDpi

---------

Summary: Icon appears in both -nodpi and dpi folders

Priority: 7 / 10

Severity: Warning

Category: Usability:Icons

Bitmaps that appear in drawable-nodpi folders will not be scaled by the

Android framework. If a drawable resource of the same name appears both in a

-nodpi folder as well as a dpi folder such as drawable-hdpi, then the behavior

is ambiguous and probably not intentional. Delete one or the other, or use

different names for the icons.

IconXmlAndPng

-------------

Summary: Icon is specified both as .xml file and as a bitmap

Priority: 7 / 10

Severity: Warning

Category: Usability:Icons

If a drawable resource appears as an .xml file in the drawable/ folder, it's

usually not intentional for it to also appear as a bitmap using the same name;

generally you expect the drawable XML file to define states and each state has

a corresponding drawable bitmap.

IconColors

----------

Summary: Icon colors do not follow the recommended visual style

Priority: 6 / 10

Severity: Warning

Category: Usability:Icons

Notification icons and Action Bar icons should only white and shades of gray.

See the Android Design Guide for more details. Note that the way Lint decides

whether an icon is an action bar icon or a notification icon is based on the

filename prefix: ic_menu_ for action bar icons, ic_stat_ for notification

icons etc. These correspond to the naming conventions documented in

http://developer.android.com/guide/practices/ui_guidelines/icon_design.html

More information:

http://developer.android.com/design/style/iconography.html

IconLauncherShape

-----------------

Summary: The launcher icon shape should use a distinct silhouette

Priority: 6 / 10

Severity: Warning

Category: Usability:Icons

According to the Android Design Guide

(http://developer.android.com/design/style/iconography.html) your launcher

icons should "use a distinct silhouette", a "three-dimensional, front view,

with a slight perspective as if viewed from above, so that users perceive some

depth."

The unique silhouette implies that your launcher icon should not be a filled

square.

More information:

http://developer.android.com/design/style/iconography.html

GifUsage

--------

Summary: Using .gif format for bitmaps is discouraged

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

The .gif file format is discouraged. Consider using .png (preferred) or .jpg

(acceptable) instead.

More information:

http://developer.android.com/guide/topics/resources/drawable-resource.html#Bitmap

IconDipSize

-----------

Summary: Icon density-independent size validation

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

Checks the all icons which are provided in multiple densities, all compute to

roughly the same density-independent pixel (dip) size. This catches errors

where images are either placed in the wrong folder, or icons are changed to

new sizes but some folders are forgotten.

IconDuplicatesConfig

--------------------

Summary: Identical bitmaps across various configurations

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

If an icon is provided under different configuration parameters such as

drawable-hdpi or -v11, they should typically be different. This detector

catches cases where the same icon is provided in different configuration

folder which is usually not intentional.

IconExpectedSize

----------------

Summary: Icon has incorrect size

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

NOTE: This issue is disabled by default!

You can enable it by adding --enable IconExpectedSize

There are predefined sizes (for each density) for launcher icons. You should

follow these conventions to make sure your icons fit in with the overall look

of the platform.

More information:

http://developer.android.com/design/style/iconography.html

IconLocation

------------

Summary: Image defined in density-independent drawable folder

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

The res/drawable folder is intended for density-independent graphics such as

shapes defined in XML. For bitmaps, move it to drawable-mdpi and consider

providing higher and lower resolution versions in drawable-ldpi, drawable-hdpi

and drawable-xhdpi. If the icon really is density independent (for example a

solid color) you can place it in drawable-nodpi.

More information:

http://developer.android.com/guide/practices/screens_support.html

IconMixedNinePatch

------------------

Summary: Clashing PNG and 9-PNG files

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

If you accidentally name two separate resources file.png and file.9.png, the

image file and the nine patch file will both map to the same drawable

resource, @drawable/file, which is probably not what was intended.

MipmapIcons

-----------

Summary: Use Mipmap Launcher Icons

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

Launcher icons should be provided in the mipmap resource directory. This is

the same as the drawable resource directory, except resources in the mipmap

directory will not get stripped out when creating density-specific APKs.

In certain cases, the Launcher app may use a higher resolution asset (than

would normally be computed for the device) to display large app shortcuts. If

drawables for densities other than the device's resolution have been stripped

out, then the app shortcut could appear blurry.

To fix this, move your launcher icons from `drawable-`dpi to `mipmap-`dpi and

change references from @drawable/ and R.drawable to @mipmap/ and R.mipmap.

In Android Studio this lint warning has a quickfix to perform this

automatically.

MissingApplicationIcon

----------------------

Summary: Missing application icon

Priority: 5 / 10

Severity: Warning

Category: Usability:Icons

You should set an icon for the application as whole because there is no

default. This attribute must be set as a reference to a drawable resource

containing the image (for example @drawable/icon).

More information:

http://developer.android.com/tools/publishing/preparing.html#publishing-configure

IconDensities

-------------

Summary: Icon densities validation

Priority: 4 / 10

Severity: Warning

Category: Usability:Icons

Icons will look best if a custom version is provided for each of the major

screen density classes (low, medium, high, extra high). This lint check

identifies icons which do not have complete coverage across the densities.

Low density is not really used much anymore, so this check ignores the ldpi

density. To force lint to include it, set the environment variable

ANDROID_LINT_INCLUDE_LDPI=true. For more information on current density usage,

see http://developer.android.com/resources/dashboard/screens.html

More information:

http://developer.android.com/guide/practices/screens_support.html

IconDuplicates

--------------

Summary: Duplicated icons under different names

Priority: 3 / 10

Severity: Warning

Category: Usability:Icons

If an icon is repeated under different names, you can consolidate and just use

one of the icons and delete the others to make your application smaller.

However, duplicated icons usually are not intentional and can sometimes point

to icons that were accidentally overwritten or accidentally not updated.

IconExtension

-------------

Summary: Icon format does not match the file extension

Priority: 3 / 10

Severity: Warning

Category: Usability:Icons

Ensures that icons have the correct file extension (e.g. a .png file is really

in the PNG format and not for example a GIF file named .png.)

IconMissingDensityFolder

------------------------

Summary: Missing density folder

Priority: 3 / 10

Severity: Warning

Category: Usability:Icons

Icons will look best if a custom version is provided for each of the major

screen density classes (low, medium, high, extra-high, extra-extra-high). This

lint check identifies folders which are missing, such as drawable-hdpi.

Low density is not really used much anymore, so this check ignores the ldpi

density. To force lint to include it, set the environment variable

ANDROID_LINT_INCLUDE_LDPI=true. For more information on current density usage,

see http://developer.android.com/resources/dashboard/screens.html

More information:

http://developer.android.com/guide/practices/screens_support.html

Usability

=========

ButtonOrder

-----------

Summary: Button order

Priority: 8 / 10

Severity: Warning

Category: Usability

According to the Android Design Guide,

"Action buttons are typically Cancel and/or OK, with OK indicating the

preferred or most likely action. However, if the options consist of specific

actions such as Close or Wait rather than a confirmation or cancellation of

the action described in the content, then all the buttons should be active

verbs. As a rule, the dismissive action of a dialog is always on the left

whereas the affirmative actions are on the right."

This check looks for button bars and buttons which look like cancel buttons,

and makes sure that these are on the left.

More information:

http://developer.android.com/design/building-blocks/dialogs.html

SelectableText

--------------

Summary: Dynamic text should probably be selectable

Priority: 7 / 10

Severity: Warning

Category: Usability

NOTE: This issue is disabled by default!

You can enable it by adding --enable SelectableText

If a <TextView> is used to display data, the user might want to copy that data

and paste it elsewhere. To allow this, the <TextView> should specify

android:textIsSelectable="true".

This lint check looks for TextViews which are likely to be displaying data:

views whose text is set dynamically. This value will be ignored on platforms

older than API 11, so it is okay to set it regardless of your minSdkVersion.

BackButton

----------

Summary: Back button

Priority: 6 / 10

Severity: Warning

Category: Usability

NOTE: This issue is disabled by default!

You can enable it by adding --enable BackButton

According to the Android Design Guide,

"Other platforms use an explicit back button with label to allow the user to

navigate up the application's hierarchy. Instead, Android uses the main action

bar's app icon for hierarchical navigation and the navigation bar's back

button for temporal navigation."

This check is not very sophisticated (it just looks for buttons with the label

"Back"), so it is disabled by default to not trigger on common scenarios like

pairs of Back/Next buttons to paginate through screens.

More information:

http://developer.android.com/design/patterns/pure-android.html

ButtonStyle

-----------

Summary: Button should be borderless

Priority: 5 / 10

Severity: Warning

Category: Usability

Button bars typically use a borderless style for the buttons. Set the

style="?android:attr/buttonBarButtonStyle" attribute on each of the buttons,

and set style="?android:attr/buttonBarStyle" on the parent layout

More information:

http://developer.android.com/design/building-blocks/buttons.html

GoogleAppIndexingApiWarning

---------------------------

Summary: Missing support for Firebase App Indexing Api

Priority: 5 / 10

Severity: Warning

Category: Usability

NOTE: This issue is disabled by default!

You can enable it by adding --enable GoogleAppIndexingApiWarning

Adds URLs to get your app into the Google index, to get installs and traffic

to your app from Google Search.

More information:

https://g.co/AppIndexing/AndroidStudio

GoogleAppIndexingUrlError

-------------------------

Summary: URL not supported by app for Firebase App Indexing

Priority: 5 / 10

Severity: Error

Category: Usability

Ensure the URL is supported by your app, to get installs and traffic to your

app from Google Search.

More information:

https://g.co/AppIndexing/AndroidStudio

GoogleAppIndexingWarning

------------------------

Summary: Missing support for Firebase App Indexing

Priority: 5 / 10

Severity: Warning

Category: Usability

Adds URLs to get your app into the Google index, to get installs and traffic

to your app from Google Search.

More information:

https://g.co/AppIndexing/AndroidStudio

MenuTitle

---------

Summary: Missing menu title

Priority: 5 / 10

Severity: Error

Category: Usability

From the action bar documentation:

"It's important that you always define android:title for each menu item — even

if you don't declare that the title appear with the action item — for three

reasons:

* If there's not enough room in the action bar for the action item, the menu

item appears in the overflow menu and only the title appears.

* Screen readers for sight-impaired users read the menu item's title.

* If the action item appears with only the icon, a user can long-press the

item to reveal a tool-tip that displays the action item's title.

The android:icon is always optional, but recommended.

More information:

http://developer.android.com/guide/topics/ui/actionbar.html

TextFields

----------

Summary: Missing inputType or hint

Priority: 5 / 10

Severity: Warning

Category: Usability

Providing an inputType attribute on a text field improves usability because

depending on the data to be input, optimized keyboards can be shown to the

user (such as just digits and parentheses for a phone number). Similarly,a

hint attribute displays a hint to the user for what is expected in the text

field.

The lint detector also looks at the id of the view, and if the id offers a

hint of the purpose of the field (for example, the id contains the phrase

phone or email), then lint will also ensure that the inputType contains the

corresponding type attributes.

If you really want to keep the text field generic, you can suppress this

warning by setting inputType="text".

NegativeMargin

--------------

Summary: Negative Margins

Priority: 4 / 10

Severity: Warning

Category: Usability

NOTE: This issue is disabled by default!

You can enable it by adding --enable NegativeMargin

Margin values should be positive. Negative values are generally a sign that

you are making assumptions about views surrounding the current one, or may be

tempted to turn off child clipping to allow a view to escape its parent.

Turning off child clipping to do this not only leads to poor graphical

performance, it also results in wrong touch event handling since touch events

are based strictly on a chain of parent-rect hit tests. Finally, making

assumptions about the size of strings can lead to localization problems.

SmallSp

-------

Summary: Text size is too small

Priority: 4 / 10

Severity: Warning

Category: Usability

Avoid using sizes smaller than 12sp.

AlwaysShowAction

----------------

Summary: Usage of showAsAction=always

Priority: 3 / 10

Severity: Warning

Category: Usability

Using showAsAction="always" in menu XML, or MenuItem.SHOW_AS_ACTION_ALWAYS in

Java code is usually a deviation from the user interface style guide.Use

ifRoom or the corresponding MenuItem.SHOW_AS_ACTION_IF_ROOM instead.

If always is used sparingly there are usually no problems and behavior is

roughly equivalent to ifRoom but with preference over other ifRoom items.

Using it more than twice in the same menu is a bad idea.

This check looks for menu XML files that contain more than two always actions,

or some always actions and no ifRoom actions. In Java code, it looks for

projects that contain references to MenuItem.SHOW_AS_ACTION_ALWAYS and no

references to MenuItem.SHOW_AS_ACTION_IF_ROOM.

More information:

http://developer.android.com/design/patterns/actionbar.html

ViewConstructor

---------------

Summary: Missing View constructors for XML inflation

Priority: 3 / 10

Severity: Warning

Category: Usability

Some layout tools (such as the Android layout editor) need to find a

constructor with one of the following signatures:

* View(Context context)

* View(Context context, AttributeSet attrs)

* View(Context context, AttributeSet attrs, int defStyle)

If your custom view needs to perform initialization which does not apply when

used in a layout editor, you can surround the given code with a check to see

if View#isInEditMode() is false, since that method will return false at

runtime but true within a user interface editor.

ButtonCase

----------

Summary: Cancel/OK dialog button capitalization

Priority: 2 / 10

Severity: Warning

Category: Usability

The standard capitalization for OK/Cancel dialogs is "OK" and "Cancel". To

ensure that your dialogs use the standard strings, you can use the resource

strings @android:string/ok and @android:string/cancel.

Accessibility

=============

ClickableViewAccessibility

--------------------------

Summary: Accessibility in Custom Views

Priority: 6 / 10

Severity: Warning

Category: Accessibility

If a View that overrides onTouchEvent or uses an OnTouchListener does not also

implement performClick and call it when clicks are detected, the View may not

handle accessibility actions properly. Logic handling the click actions should

ideally be placed in View#performClick as some accessibility services invoke

performClick when a click action should occur.

ContentDescription

------------------

Summary: Image without contentDescription

Priority: 3 / 10

Severity: Warning

Category: Accessibility

Non-textual widgets like ImageViews and ImageButtons should use the

contentDescription attribute to specify a textual description of the widget

such that screen readers and other accessibility tools can adequately describe

the user interface.

Note that elements in application screens that are purely decorative and do

not provide any content or enable a user action should not have accessibility

content descriptions. In this case, just suppress the lint warning with a

tools:ignore="ContentDescription" attribute.

Note that for text fields, you should not set both the hint and the

contentDescription attributes since the hint will never be shown. Just set the

hint. See

http://developer.android.com/guide/topics/ui/accessibility/checklist.html#spec

al-cases.

LabelFor

--------

Summary: Missing labelFor attribute

Priority: 2 / 10

Severity: Warning

Category: Accessibility

Text fields should be labelled with a labelFor attribute, provided your

minSdkVersion is at least 17.

If your view is labeled but by a label in a different layout which includes

this one, just suppress this warning from lint.

Internationalization

====================

ByteOrderMark

-------------

Summary: Byte order mark inside files

Priority: 8 / 10

Severity: Fatal

Category: Internationalization

Lint will flag any byte-order-mark (BOM) characters it finds in the middle of

a file. Since we expect files to be encoded with UTF-8 (see the EnforceUTF8

issue), the BOM characters are not necessary, and they are not handled

correctly by all tools. For example, if you have a BOM as part of a resource

name in one particular translation, that name will not be considered identical

to the base resource's name and the translation will not be used.

More information:

http://en.wikipedia.org/wiki/Byte_order_mark

SetTextI18n

-----------

Summary: TextView Internationalization

Priority: 6 / 10

Severity: Warning

Category: Internationalization

When calling TextView#setText

* Never call Number#toString() to format numbers; it will not handle fraction

separators and locale-specific digits properly. Consider using String#format

with proper format specifications (%d or %f) instead.

* Do not pass a string literal (e.g. "Hello") to display text. Hardcoded text

can not be properly translated to other languages. Consider using Android

resource strings instead.

* Do not build messages by concatenating text chunks. Such messages can not be

properly translated.

More information:

http://developer.android.com/guide/topics/resources/localization.html

EnforceUTF8

-----------

Summary: Encoding used in resource files is not UTF-8

Priority: 5 / 10

Severity: Fatal

Category: Internationalization

XML supports encoding in a wide variety of character sets. However, not all

tools handle the XML encoding attribute correctly, and nearly all Android apps

use UTF-8, so by using UTF-8 you can protect yourself against subtle bugs when

using non-ASCII characters.

In particular, the Android Gradle build system will merge resource XML files

assuming the resource files are using UTF-8 encoding.

HardcodedText

-------------

Summary: Hardcoded text

Priority: 5 / 10

Severity: Warning

Category: Internationalization

Hardcoding text attributes directly in layout files is bad for several

reasons:

* When creating configuration variations (for example for landscape or

portrait)you have to repeat the actual text (and keep it up to date when

making changes)

* The application cannot be translated to other languages by just adding new

translations for existing string resources.

There are quickfixes to automatically extract this hardcoded string into a

resource lookup.

RelativeOverlap

---------------

Summary: Overlapping items in RelativeLayout

Priority: 3 / 10

Severity: Warning

Category: Internationalization

If relative layout has text or button items aligned to left and right sides

they can overlap each other due to localized text expansion unless they have

mutual constraints like toEndOf/toStartOf.

Internationalization:Bidirectional Text

=======================================

RtlCompat

---------

Summary: Right-to-left text compatibility issues

Priority: 6 / 10

Severity: Error

Category: Internationalization:Bidirectional Text

API 17 adds a textAlignment attribute to specify text alignment. However, if

you are supporting older versions than API 17, you must also specify a gravity

or layout_gravity attribute, since older platforms will ignore the

textAlignment attribute.

RtlSymmetry

-----------

Summary: Padding and margin symmetry

Priority: 6 / 10

Severity: Warning

Category: Internationalization:Bidirectional Text

If you specify padding or margin on the left side of a layout, you should

probably also specify padding on the right side (and vice versa) for

right-to-left layout symmetry.

RtlHardcoded

------------

Summary: Using left/right instead of start/end attributes

Priority: 5 / 10

Severity: Warning

Category: Internationalization:Bidirectional Text

Using Gravity#LEFT and Gravity#RIGHT can lead to problems when a layout is

rendered in locales where text flows from right to left. Use Gravity#START and

Gravity#END instead. Similarly, in XML gravity and layout_gravity attributes,

use start rather than left.

For XML attributes such as paddingLeft and layout_marginLeft, use paddingStart

and layout_marginStart. NOTE: If your minSdkVersion is less than 17, you

should add both the older left/right attributes as well as the new start/right

attributes. On older platforms, where RTL is not supported and the start/right

attributes are unknown and therefore ignored, you need the older left/right

attributes. There is a separate lint check which catches that type of error.

(Note: For Gravity#LEFT and Gravity#START, you can use these constants even

when targeting older platforms, because the start bitmask is a superset of the

left bitmask. Therefore, you can use gravity="start" rather than

gravity="left|start".)

RtlEnabled

----------

Summary: Using RTL attributes without enabling RTL support

Priority: 3 / 10

Severity: Warning

Category: Internationalization:Bidirectional Text

To enable right-to-left support, when running on API 17 and higher, you must

set the android:supportsRtl attribute in the manifest <application> element.

If you have started adding RTL attributes, but have not yet finished the

migration, you can set the attribute to false to satisfy this lint check.