test.xml:
<layout xmlns:android="http://schemas.android.com/apk/res/android">
    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    <include
        android:id="@+id/include_content"
        layout="@layout/content" />
    </FrameLayout>
 </layout>
content.xml:
<layout  xmlns:android="http://schemas.android.com/apk/res/android">
  <FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="test button"/>
  </FrameLayout>
</layout>
Java Code:
@Override
public void onCreate(Bundle savedInstanceState, PersistableBundle persistentState) {
    super.onCreate(savedInstanceState, persistentState);
   TestBinding binding=DataBindingUtil.setContentView(this, R.layout.test);       
          Button button = binding.includeContent.button;
}
when i run the application , Android studio build error 'cannot find symbol variable includeContent'
what do i miss?
 
     
    