2.12 综合运用使用

最近学习的Android 内容如下：

还有自己找的一些解释介绍：

ViewModel ： https://www.jianshu.com/p/35d143e84d42

LiveData ：https://www.jianshu.com/p/21bb6c0f8a5a

DataBinding ： https://www.jianshu.com/p/d3d8f842b5ec

Vector Drawable ： https://www.jianshu.com/p/c4c7906d5bc3

Screen Orientation Localization

按照视频所学制作了一个比赛计分器 https://www.bilibili.com/video/av50954019?p=13

效果图如下：

功能简介：左右为队伍 A B的得分计数

点击进行分数添加撤销按钮可返回一次上次的分数操作

重置按钮重置记录的成绩（点击home键之后可以读取保存数据并后台运行）

退出后无法保存数据

需要添加一下代码

1 android.defaultConfig.vectorDrawables.useSupportLibrary = true   //向下兼容   保证app在不同版本安卓系统的兼容性
2         dataBinding {                         //允许使用dataBinding
3             enabled true
4         }

MyViewModel 实现程序功能

 1 package com.example.score;
 2 
 3 import androidx.lifecycle.MutableLiveData;
 4 import androidx.lifecycle.ViewModel;
 5 
 6 public class MyviewModel extends ViewModel {
 7     private static MutableLiveData<Integer> aTeamScore;
 8     private static MutableLiveData<Integer> bTeamScore;
 9     private static int aBack,bBack;
10 
11     public MutableLiveData<Integer> getaTeamScore() {
12         if(aTeamScore==null){                   //如果为空 则初始化 为 0
13             aTeamScore = new MutableLiveData<>();
14             aTeamScore.setValue(0);
15         }
16         return aTeamScore;
17     }
18 
19     public MutableLiveData<Integer> getbTeamScore() {
20         if(bTeamScore==null){
21            bTeamScore = new MutableLiveData<>();
22            bTeamScore.setValue(0);
23         }
24         return bTeamScore;
25     }
26 
27 
28     public void aTeamAdd(int p){    //对分数进行修改
29         aBack =aTeamScore.getValue();  //存储上一次操作的数据
30         bBack= bTeamScore.getValue();
31         aTeamScore.setValue(aTeamScore.getValue()+p);
32     }
33 
34     public void bTeamAdd(int p){
35         aBack =aTeamScore.getValue();  //存储上一次操作的数据  存储两个避免两个分数同时被撤销
36         bBack= bTeamScore.getValue();
37         bTeamScore.setValue(bTeamScore.getValue()+p);
38     }
39 
40     public void  reset(){   //重置操作
41         aBack =aTeamScore.getValue();  //存储上一次操作的数据
42         bBack= bTeamScore.getValue();
43         aTeamScore.setValue(0);
44         bTeamScore.setValue(0);
45     }
46 
47     public void undo(){  //撤销操作
48         aTeamScore.setValue(aBack);
49         bTeamScore.setValue(bBack);
50     }
51 }

MainActivity.java

在视频讲解当中使用了 ViewModelProviders

但是现版本已经去除如果继续使用会是按钮点击但无法进行操作

改为 MyviewModel myviewModel = new ViewModelProvider(this).get(MyviewModel.class); 即可

 1 package com.example.score;
 2 
 3 import androidx.appcompat.app.AppCompatActivity;
 4 import androidx.databinding.DataBindingUtil;
 5 import androidx.lifecycle.ViewModelProvider;
 6 //import androidx.lifecycle.ViewModelProviders;
 7 
 8 import android.os.Bundle;
 9 
10 import com.example.score.databinding.ActivityMainBinding;
11 
12 public class MainActivity extends AppCompatActivity {
13     MyviewModel myviewModel;
14     ActivityMainBinding binding;
15 
16     @Override
17     protected void onCreate(Bundle savedInstanceState) {
18         super.onCreate(savedInstanceState);
19         binding = DataBindingUtil.setContentView(this,R.layout.activity_main);
20         myviewModel = new ViewModelProvider(this).get(MyviewModel.class);
21        // ViewModelProviders.of(this).get(MyviewModel.class);
22         binding.setData(myviewModel);
23         binding.setLifecycleOwner(this);
24     }
25 }

databinding 修改后的 Activity_main.xml 的text

  1 <?xml version="1.0" encoding="utf-8"?>
  2 <layout xmlns:android="http://schemas.android.com/apk/res/android"
  3     xmlns:app="http://schemas.android.com/apk/res-auto"
  4     xmlns:tools="http://schemas.android.com/tools">
  5 
  6     <data>    //添加的变量 通过此修改下面的命令
  7         <variable
  8             name="data"
  9             type="com.example.score.MyviewModel" />
 10     </data>
 11 
 12     <androidx.constraintlayout.widget.ConstraintLayout
 13         android:layout_width="match_parent"
 14         android:layout_height="match_parent"
 15         tools:context=".MainActivity">
 16 
 17         <androidx.constraintlayout.widget.Guideline
 18             android:id="@+id/guideline"
 19             android:layout_width="wrap_content"
 20             android:layout_height="wrap_content"
 21             android:orientation="vertical"
 22             app:layout_constraintGuide_percent="0.5" />
 23 
 24         <androidx.constraintlayout.widget.Guideline
 25             android:id="@+id/guideline2"
 26             android:layout_width="wrap_content"
 27             android:layout_height="wrap_content"
 28             android:orientation="horizontal"
 29             app:layout_constraintGuide_percent="0.05" />
 30 
 31         <androidx.constraintlayout.widget.Guideline
 32             android:id="@+id/guideline3"
 33             android:layout_width="wrap_content"
 34             android:layout_height="wrap_content"
 35             android:orientation="horizontal"
 36             app:layout_constraintGuide_percent="0.15" />
 37 
 38         <androidx.constraintlayout.widget.Guideline
 39             android:id="@+id/guideline4"
 40             android:layout_width="wrap_content"
 41             android:layout_height="wrap_content"
 42             android:orientation="horizontal"
 43             app:layout_constraintGuide_percent="0.35" />
 44 
 45         <androidx.constraintlayout.widget.Guideline
 46             android:id="@+id/guideline5"
 47             android:layout_width="wrap_content"
 48             android:layout_height="wrap_content"
 49             android:orientation="horizontal"
 50             app:layout_constraintGuide_percent="0.5" />
 51 
 52         <androidx.constraintlayout.widget.Guideline
 53             android:id="@+id/guideline6"
 54             android:layout_width="wrap_content"
 55             android:layout_height="wrap_content"
 56             android:orientation="horizontal"
 57             app:layout_constraintGuide_percent="0.65" />
 58 
 59         <androidx.constraintlayout.widget.Guideline
 60             android:id="@+id/guideline7"
 61             android:layout_width="wrap_content"
 62             android:layout_height="wrap_content"
 63             android:orientation="horizontal"
 64             app:layout_constraintGuide_percent="0.8" />
 65 
 66         <androidx.constraintlayout.widget.Guideline
 67             android:id="@+id/guideline8"
 68             android:layout_width="wrap_content"
 69             android:layout_height="wrap_content"
 70             android:orientation="horizontal"
 71             app:layout_constraintGuide_percent="0.9" />
 72 
 73         <TextView
 74             android:id="@+id/textView"
 75             android:layout_width="wrap_content"
 76             android:layout_height="wrap_content"
 77             android:text="@string/textview1"
 78             android:textSize="@dimen/teamTextSize"
 79             app:layout_constraintBottom_toTopOf="@+id/guideline3"
 80             app:layout_constraintEnd_toStartOf="@+id/guideline"
 81             app:layout_constraintStart_toStartOf="parent"
 82             app:layout_constraintTop_toTopOf="@+id/guideline2" />
 83 
 84         <TextView
 85             android:id="@+id/textView2"
 86             android:layout_width="wrap_content"
 87             android:layout_height="wrap_content"
 88             android:text="@string/textview2"
 89             android:textSize="@dimen/teamTextSize"
 90             app:layout_constraintBottom_toTopOf="@+id/guideline3"
 91             app:layout_constraintEnd_toEndOf="parent"
 92             app:layout_constraintStart_toStartOf="@+id/guideline"
 93             app:layout_constraintTop_toTopOf="@+id/guideline2" />
 94 
 95         <TextView
 96             android:id="@+id/textView3"
 97             android:layout_width="wrap_content"
 98             android:layout_height="wrap_content"
 99             android:text="@{String.valueOf(data.getaTeamScore())}"  
100             android:textColor="@color/colorAccent"
101             android:textSize="@dimen/scoreTextSize"
102             app:layout_constraintBottom_toTopOf="@+id/guideline4"
103             app:layout_constraintEnd_toStartOf="@+id/guideline"
104             app:layout_constraintStart_toStartOf="parent"
105             app:layout_constraintTop_toTopOf="@+id/guideline3"
106             tools:text="120" />
107 
108         <TextView
109             android:id="@+id/textView4"
110             android:layout_width="wrap_content"
111             android:layout_height="wrap_content"
112             android:text="@{String.valueOf(data.getbTeamScore())}"
113             android:textColor="@color/colorPrimary"
114             android:textSize="@dimen/scoreTextSize"
115             app:layout_constraintBottom_toTopOf="@+id/guideline4"
116             app:layout_constraintEnd_toEndOf="parent"
117             app:layout_constraintStart_toStartOf="@+id/guideline"
118             app:layout_constraintTop_toTopOf="@+id/guideline3"
119             tools:text="88" />
120 
121         <Button
122             android:id="@+id/button"
123             android:layout_width="0dp"
124             android:layout_height="wrap_content"
125             android:background="@color/colorAccent"
126             android:text="@string/button1"
127             android:textColor="@android:color/white"
128             android:textSize="@dimen/buttonTextSize"
129             android:onClick="@{()->data.aTeamAdd(1)}"
130             app:layout_constraintBottom_toTopOf="@+id/guideline5"
131             app:layout_constraintEnd_toStartOf="@+id/guideline"
132             app:layout_constraintStart_toStartOf="parent"
133             app:layout_constraintTop_toTopOf="@+id/guideline4" />
134 
135         <Button
136             android:id="@+id/button2"
137             android:layout_width="0dp"
138             android:layout_height="wrap_content"
139             android:background="@color/colorPrimary"
140             android:text="@string/button1"
141             android:textColor="@android:color/white"
142             android:textSize="@dimen/buttonTextSize"
143             android:onClick="@{()->data.bTeamAdd(1)}"
144             app:layout_constraintBottom_toTopOf="@+id/guideline5"
145             app:layout_constraintEnd_toEndOf="parent"
146             app:layout_constraintStart_toStartOf="@+id/guideline"
147             app:layout_constraintTop_toTopOf="@+id/guideline4" />
148 
149         <Button
150             android:id="@+id/button3"
151             android:layout_width="0dp"
152             android:layout_height="wrap_content"
153             android:background="@color/colorAccent"
154             android:text="@string/button2"
155             android:textColor="@android:color/white"
156             android:textSize="@dimen/buttonTextSize"
157             android:onClick="@{()->data.aTeamAdd(2)}"
158             app:layout_constraintBottom_toTopOf="@+id/guideline6"
159             app:layout_constraintEnd_toStartOf="@+id/guideline"
160             app:layout_constraintStart_toStartOf="parent"
161             app:layout_constraintTop_toTopOf="@+id/guideline5" />
162 
163         <Button
164             android:id="@+id/button4"
165             android:layout_width="0dp"
166             android:layout_height="wrap_content"
167             android:background="@color/colorPrimary"
168             android:text="@string/button2"
169             android:textColor="@android:color/white"
170             android:textSize="@dimen/buttonTextSize"
171             android:onClick="@{()->data.bTeamAdd(2)}"
172             app:layout_constraintBottom_toTopOf="@+id/guideline6"
173             app:layout_constraintEnd_toEndOf="parent"
174             app:layout_constraintStart_toStartOf="@+id/guideline"
175             app:layout_constraintTop_toTopOf="@+id/guideline5" />
176 
177         <Button
178             android:id="@+id/button5"
179             android:layout_width="0dp"
180             android:layout_height="wrap_content"
181             android:background="@color/colorAccent"
182             android:text="@string/button3"
183             android:textColor="@android:color/white"
184             android:textSize="@dimen/buttonTextSize"
185             android:onClick="@{()->data.aTeamAdd(3)}"
186             app:layout_constraintBottom_toTopOf="@+id/guideline7"
187             app:layout_constraintEnd_toStartOf="@+id/guideline"
188             app:layout_constraintStart_toStartOf="parent"
189             app:layout_constraintTop_toTopOf="@+id/guideline6" />
190 
191         <Button
192             android:id="@+id/button6"
193             android:layout_width="0dp"
194             android:layout_height="wrap_content"
195             android:background="@color/colorPrimary"
196             android:text="@string/button3"
197             android:textColor="@android:color/white"
198             android:textSize="@dimen/buttonTextSize"
199             android:onClick="@{()->data.bTeamAdd(3)}"
200             app:layout_constraintBottom_toTopOf="@+id/guideline7"
201             app:layout_constraintEnd_toEndOf="parent"
202             app:layout_constraintStart_toStartOf="@+id/guideline"
203             app:layout_constraintTop_toTopOf="@+id/guideline6" />
204 
205         <ImageButton
206             android:id="@+id/imageButton"
207             android:layout_width="wrap_content"
208             android:layout_height="wrap_content"
209             android:contentDescription="@string/undobutton"
210             android:onClick="@{()->data.undo()}"
211             app:layout_constraintBottom_toTopOf="@+id/guideline8"
212             app:layout_constraintEnd_toStartOf="@+id/guideline"
213             app:layout_constraintHorizontal_bias="0.8"
214             app:layout_constraintStart_toStartOf="parent"
215             app:layout_constraintTop_toTopOf="@+id/guideline7"
216             app:srcCompat="@drawable/ic_undo_black_24dp" />
217 
218         <ImageButton
219             android:id="@+id/imageButton2"
220             android:layout_width="wrap_content"
221             android:layout_height="wrap_content"
222             android:contentDescription="@string/resetbutton"
223             android:onClick="@{()->data.reset()}"
224             app:layout_constraintBottom_toTopOf="@+id/guideline8"
225             app:layout_constraintEnd_toEndOf="parent"
226             app:layout_constraintHorizontal_bias="0.2"
227             app:layout_constraintStart_toStartOf="@+id/guideline"
228             app:layout_constraintTop_toTopOf="@+id/guideline7"
229             app:srcCompat="@drawable/ic_loop_black_24dp" />
230 
231     </androidx.constraintlayout.widget.ConstraintLayout>
232 </layout>

emmm 目前初学阶段只能照猫画虎的学。努力下去，一定会有收获。

2.12 综合运用 使用

2.12 综合运用使用