java - Android: Change button text after MediaPlayer audio ends

Question

So I'm following Big Nerd Ranch's Android Programming book and I have an audio file playing through MediaPLayer. I also have a button that both plays and pauses the audio. If you press the play button to play the audio the text on the button changes to "pause". The problems is after the audio ends the button still says "pause" so the user has to press the button twice to play the audio again. How would I get the button to change its text to "play right after the audio ends"

Here's my code minus the layout xml for the buttons

Fragment class:

public class HelloMoonFragment extends Fragment {

    private Button mPlayButton;
    private Button mStopButton;

    private AudioPlayer mPlayer = new AudioPlayer();

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_hello_moon, parent, false);

        mPlayButton = (Button)v.findViewById(R.id.hellomoon_playButton);
        mPlayButton.setText("Play");
        mPlayButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v) {
                if(mPlayButton.getText().equals("Play")) {
                    mPlayButton.setText("Pause");
                    mPlayer.play(getActivity());
                }
                else if(mPlayButton.getText().equals("Pause")){
                    mPlayButton.setText("Play");
                    mPlayer.pause();
                }
            }
        });

        mStopButton = (Button)v.findViewById(R.id.hellomoon_stopButton);
        mStopButton.setOnClickListener(new View.OnClickListener() {
           public void onClick(View v) {
               mPlayer.stop();
               mPlayButton.setText("Play");
           }
        });

        return v;
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        mPlayer.stop();
    }
}

MediaPlayer class:

package com.bignerdranch.android.hellomoon;

import android.content.Context;
import android.media.MediaPlayer;

public class AudioPlayer {

    private MediaPlayer mPlayer;
    private boolean mCompleted =  false;

    public void stop() {
        if (mPlayer != null) {
            mPlayer.release();
            mPlayer = null;
        }
    }

    public void play(Context c) {

        if(mPlayer == null) {
            mPlayer = MediaPlayer.create(c, R.raw.one_small_step);

            mPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
                public void onCompletion(MediaPlayer mp) {
                    stop();
                    mCompleted = true;
                }
            });
        }
            mPlayer.start();
    }

    public void pause() {
        if(mPlayer != null) mPlayer.pause();
    }
}

Answer 1

If you use the MediaPlayer class directly on the activity, then you can use its OnCompletionListener to detect if the media stops playing. inside this OnCompletionListener you can switch your button's text from "Pause" to "Play" like so:

mPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
    public void onCompletion(MediaPlayer mp) {
        mPlayButton.setText("Play");
    }
});

I integrated your AudioPlayer to the fragment so that it would look like:

public class HelloMoonFragment extends Fragment {

    private Button mPlayButton;
    private Button mStopButton;

    private MediaPlayer mPlayer;
    private boolean mCompleted =  false;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup parent, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_hello_moon, parent, false);

        mPlayButton = (Button) v.findViewById(R.id.hellomoon_playButton);
        mPlayButton.setText("Play");

        mPlayButton.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v) {

                if(mPlayer == null) {
                    mPlayer = MediaPlayer.create(c, R.raw.one_small_step);
                    mPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
                        public void onCompletion(MediaPlayer mp) {
                            stopMediaPlayer();
                            mPlayButton.setText("Play");
                        }
                    });
                }

                if(mPlayButton.getText().equals("Play")) {
                    mPlayButton.setText("Pause");
                    mPlayer.start();
                }
                else if(mPlayButton.getText().equals("Pause")){
                    mPlayButton.setText("Play");
                    mPlayer.pause();
                }
            }
        });

        mStopButton = (Button)v.findViewById(R.id.hellomoon_stopButton);
        mStopButton.setOnClickListener(new View.OnClickListener() {
           public void onClick(View v) {
                stopMediaPlayer();
                mPlayButton.setText("Play");
           }
        });

        return v;
    }

    @Override
    public void onDestroy() {
        stopMediaPlayer();
        super.onDestroy();
    }


    public void stopMediaPlayer() {
        if (mPlayer != null) {
            mPlayer.release();
            mPlayer = null;
        }
    }
}