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 {

    ...18 
    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() * 1000).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() * 1000).toInt()
        data.key = "新Main key$random"
        data.value = random
        binding.data = data
    }

或者

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

3.3 伴生对象的成员也不自动更新

也要手动   binding.invalidateAll()