How can a view detect when it's being attached to its parent?

Question

I have a View that needs to detect when it's being attached to its parent view.

In a ViewGroup I have the OnHierarchyChangeListener which allows me to know when a child view is being added / removed, but I need the opposite thing.

Answer 1

You can create custom view and do your stuff in its onAttachedToWindow

public class CustomView extends View {

   public CustomView(Context context) {
       super(context);
   }

   @Override
   protected void onAttachedToWindow() {
       super.onAttachedToWindow();
       Log.d("CustomView", "onAttachedToWindow called for " + getId());
       Toast.makeText(getContext(), "added", 1000).show();
   }
}

[EDIT 1]

you can ensure that your customview added to correct viewgroup which you want

@Override
 protected void onAttachedToWindow() {
    // TODO Auto-generated method stub
    super.onAttachedToWindow();

    if(((View)getParent()).getId()== R.id.relativelayout2)
    {           
        Log.d("CustomView","onAttachedToWindow called for " + getId());
        Toast.makeText(context, "added", 1000).show();          
    }

}

Answer 2

Solution without having to create a custom view

If the View is one you can't or don't want to modify, you can use View.addOnAttachStateChangeListener to get hooks when the view is attached to the view hierarchy and when it is detached from the view hierarchy.

Something like:

Kotlin

view.addOnAttachStateChangeListener(object : View.OnAttachStateChangeListener {
  override fun onViewAttachedToWindow(v: View) {
    // Do stuff when view has been attached to window
  }

  override fun onViewDetachedFromWindow(v: View) {
    // Do stuff when view has been detached from window
  }
})

Java

view.addOnAttachStateChangeListener(new View.OnAttachStateChangeListener() {
  @Override
  public void onViewAttachedToWindow(View v) {
    // Do stuff when view has been attached to window
  }

  @Override
  public void onViewDetachedFromWindow(View v) {
    // Do stuff when view has been detached from window
  }
});