android 数据绑定(5) kotlin 的binding bug

1.BR找不到，无法自动更新

1.1 描述

　　https://stackoverflow.com/questions/57983508/android-studio-kotlin-databinding-unresolved-reference-on-br

I have some code that is generating a "red squiggly" error in Android Studio:
```
1 @get:Bindable
2 var title: String = ""
3     set(value) {
4         field = value
5         notifyPropertyChanged(BR.title)
6     }
```
It complains that "title" is an unresolved reference on BR.title. Building and running works fine though, and this is the only error I can see. I debug there and see that it's gotten the value for BR.title correctly.

Still, I can't figure out how to make it go away. I verified that the generated BR class has the "title" field, but Android Studio refuses to recognize this. I've looked up people having this issue and have tried the following: (unsuccessfully)
- Closing Android Studio, deleting the .gradle, .idea and build folders and restarting
- Build -> Clean Project, Rebuild Project
- File -> Invalidate Caches and restart
- Disabling and enabling the Kotlin plugin
- Closing and reopening the project
I have also checked and I have apply plugin: 'kotlin-kapt' in build.gradle.

1.2 解决方法

 1 apply plugin: 'com.android.application'
 2 
 3 apply plugin: 'kotlin-android'
 4 apply plugin: 'kotlin-kapt'
 5 apply plugin: 'kotlin-android-extensions'
 6 
 7 android {
 8 
 9     dataBinding {
10         enabled = true
11     }
12 
13 }
14 
15 dependencies {
16 
17     ...18 
19     kapt 'com.android.databinding:compiler:3.2.0-alpha10'
20 }

apply plugin: 'kotlin-kapt'
kapt 'com.android.databinding:compiler:3.2.0-alpha10'

2. 闪烁bug

item使用数据绑定时，当复用ViewHolder时，会有闪烁问题，或者排序问题，

复现方法：

关闭RecyclerView item的动画，
多准备条数据，超过1屏，上下滚动，长按item进入编辑状态，选中item，就会出现。

3.不自动更新

3.1 问题描述

　　kotlin与Java 混合时， kotlin修改java里的data ,不自动更新

定义类

 1 public class Data extends BaseObservable {
 2 
 3     public int      icon    ;
 4     public String   key     ;
 5     public int      value   ;
 6     public String   test     = "";
 7 
 8     @Bindable public String getKey() { return key;}
 9     @Bindable public int getValue() { return value; }
10     @Bindable public int getIcon() {
11         return icon;
12     }
13     @Bindable public String getTest(){
14         return test;
15     }
16 
17     public void setKey(String key) {
18         this.key = key;
19         notifyPropertyChanged(BR.key);
20     }
21 
22     public void setValue(int value) {
23         this.value = value;
24         notifyPropertyChanged(BR.value);
25     }
26     public void setIcon(int icon) {
27         this.icon = icon;
28         notifyPropertyChanged(BR.icon);
29     }
30     public void setTest(String ss){
31         this.test = ss;
32         notifyPropertyChanged(BR.test);
33     }
34 
35     @Override
36     public String toString() {
37         return "key = " + key + " value = " + value;
38     }
39 }

布局中

 1         <TextView
 2             android:id="@+id/data_key"
 3             android:layout_width="wrap_content"
 4             android:layout_height="wrap_content"
 5             android:layout_marginStart="32dp"
 6             android:layout_marginLeft="32dp"
 7             android:layout_marginTop="32dp"
 8             android:text='@{data.key}'
 9             app:layout_constraintStart_toStartOf="@+id/data_title"
10             app:layout_constraintTop_toBottomOf="@+id/data_title" />
11 
12         <TextView
13             android:id="@+id/data_value"
14             android:layout_width="wrap_content"
15             android:layout_height="wrap_content"
16             android:layout_marginStart="16dp"
17             android:layout_marginLeft="16dp"
18             android:text='@{String.valueOf(data.value)}'
19             app:layout_constraintStart_toEndOf="@+id/data_key"
20             app:layout_constraintTop_toTopOf="@+id/data_key" />

修改data值

1     fun onDataThreadMainClicked(view: View){
2         val random = (Math.random() * 1000).toInt()
3         data.key = "新Main key$random"
4         data.value = random
5         binding.data = data
6     }

　　结果：界面不刷新

3.2 解决办法

1      fun onDataThreadMainClicked(view: View){
2         val random = (Math.random() * 1000).toInt()
3         data.key = "新Main key$random"
4         data.value = random
5         binding.data = data
6     }

或者

1     fun onDataThreadMainClicked(view: View){
2         val random = (Math.random() * 1000).toInt()
3         data.key = "新Main key$random"
4         data.value = random
5         binding.invalidateAll()
6     }

3.3 伴生对象的成员也不自动更新

也要手动 binding.invalidateAll()