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:

   @get:Bindable
   var title: String = ""
       set(value) {
           field = value
           notifyPropertyChanged(BR.title)
       }

  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

 apply plugin: 'com.android.application'

 apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-kapt'
 apply plugin: 'kotlin-android-extensions'

 android {

     dataBinding {
         enabled = true
     }

 }

 dependencies {

     ...
     kapt 'com.android.databinding:compiler:3.2.0-alpha10'
 }

• 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：

1. 关闭RecyclerView item的动画，
2. 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

   public class Data extends BaseObservable {
  
       public int      icon    ;
       public String   key     ;
       public int      value   ;
       public String   test     = "";
  
       @Bindable public String getKey() { return key;}
       @Bindable public int getValue() { return value; }
       @Bindable public int getIcon() {
           return icon;
       }
       @Bindable public String getTest(){
           return test;
       }
  
       public void setKey(String key) {
           this.key = key;
           notifyPropertyChanged(BR.key);
       }
  
       public void setValue(int value) {
           this.value = value;
           notifyPropertyChanged(BR.value);
       }
       public void setIcon(int icon) {
           this.icon = icon;
           notifyPropertyChanged(BR.icon);
       }
       public void setTest(String ss){
           this.test = ss;
           notifyPropertyChanged(BR.test);
       }
  
       @Override
       public String toString() {
           return "key = " + key + " value = " + value;
       }
   }

• 布局中

           <TextView
               android:id="@+id/data_key"
               android:layout_width="wrap_content"
               android:layout_height="wrap_content"
               android:layout_marginStart="32dp"
               android:layout_marginLeft="32dp"
               android:layout_marginTop="32dp"
               android:text='@{data.key}'
               app:layout_constraintStart_toStartOf="@+id/data_title"
               app:layout_constraintTop_toBottomOf="@+id/data_title" />
  
           <TextView
               android:id="@+id/data_value"
               android:layout_width="wrap_content"
               android:layout_height="wrap_content"
               android:layout_marginStart="16dp"
               android:layout_marginLeft="16dp"
               android:text='@{String.valueOf(data.value)}'
               app:layout_constraintStart_toEndOf="@+id/data_key"
               app:layout_constraintTop_toTopOf="@+id/data_key" />

• 修改data值

       fun onDataThreadMainClicked(view: View){
           val random = (Math.random() * ).toInt()
           data.key = "新Main key$random"
           data.value = random
           binding.data = data
       }

　　结果：界面不刷新

3.2 解决办法

      fun onDataThreadMainClicked(view: View){
         val random = (Math.random() * ).toInt()
         data.key = "新Main key$random"
         data.value = random
         binding.data = data
     }

或者

     fun onDataThreadMainClicked(view: View){
         val random = (Math.random() * ).toInt()
         data.key = "新Main key$random"
         data.value = random
         binding.invalidateAll()
     }