How to create our own Listener interface in android?

Question

Could someone help me to create user defined listener interface with some code snippets?

Answer 1

I have done it something like below for sending my model class from the Second Activity to First Activity. I used LiveData to achieve this, with the help of answers from Rupesh and TheCodeFather.

Second Activity

public static MutableLiveData getLiveSong() {
        MutableLiveData result = new MutableLiveData<>();
        result.setValue(liveSong);
        return result;
    }

"liveSong" is AudioListModel declared globally

Call this method in the First Activity

PlayerActivity.getLiveSong().observe(this, new Observer() {
            @Override
            public void onChanged(AudioListModel audioListModel) {
                if (PlayerActivity.mediaPlayer != null && PlayerActivity.mediaPlayer.isPlaying()) {
                    Log.d("LiveSong--->Changes-->", audioListModel.getSongName());
                }
            }
        });

May this help for new explorers like me.