How to reverse Fragment Transaction with Back button on a Media Controller?

Question

I am trying to reverse a fragment transaction to bring the user back to the previous fragment when the user hits the back button. Problem is, there is a media controller and so, the back button event will be handled by dispatchKeyEvent.I've tried to manually call onBackPressed as follows but I receive a null pointer exception.

MainActivity obj;

  public boolean dispatchKeyEvent(KeyEvent event) {
        obj = new MainActivity();
        int keyCode = event.getKeyCode();
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            System.out.println(obj);
            obj.onBackPressed();
        }
        return super.dispatchKeyEvent(event);
    }

In my main activity, my fragment transaction is as follows:

            transaction = getSupportFragmentManager().beginTransaction();
            transaction.replace(R.id.fragment_container, newFragment);
            transaction.addToBackStack(null);
            transaction.commit();

What is the best way that I can handle the back button to involve reversing the fragment transaction and the MediaController?

Thanks

score 1 · Answer 1 · answered Dec 19 '15 at 13:28

1

Override this method of fragment to get the reference of the activity object

MainActivity obj;
@Override
public void onAttach(Context context) {
    super.onAttach(context);
    obj = (MainActivity) obj;    
}

Remove the object creation in dispatchKeyEvent().

answered Dec 19 '15 at 13:28

Nigam Patro

2,760
1
18
33

Hi, I tried this but it flags me an error saying cannot resolve method onAttach. Do I declare this method in the MediaController Class or Main Activity? – Lew Wei Hao Dec 19 '15 at 13:46
@LewWeiHao declare this in fragment. – Nigam Patro Dec 19 '15 at 13:51

How to reverse Fragment Transaction with Back button on a Media Controller?

1 Answers1