onAttach(Activity) deprecated: where I can check if the activity implements callback interface

Question

Before API 23 I used Fragment's onAttach methods to get my listener instance, then the reference is cleaned inside onDetach. ex:

@Override public void onAttach(Activity activity) {     super.onAttach(activity);     mListener = null;     try {         mListener = (SellFragmentListener) activity;     } catch (ClassCastException e) {         throw new ClassCastException(activity.toString()                 + " must implement SellFragmentListener");     } }  @Override public void onDetach() {     super.onDetach();     mListener = null; } 

Is it safe to do the same check inside onAttach(Context context) or is there a better way to get the holder activity instance?

Answer 1

Check the source code:

/**  * Called when a fragment is first attached to its context.  * {@link #onCreate(Bundle)} will be called after this.  */ public void onAttach(Context context) {     mCalled = true;     final Activity hostActivity = mHost == null ? null : mHost.getActivity();     if (hostActivity != null) {         mCalled = false;         onAttach(hostActivity);     } }  /**  * @deprecated Use {@link #onAttach(Context)} instead.  */ @Deprecated public void onAttach(Activity activity) {     mCalled = true; } 

So the onAttach(Activity activity) is called by the onAttach(Context context) if there is a host activity. You can use the onAttach(Activity activity) safely.