Android app plays sound only one time

Question

My app only plays a sound only once. The play sound methods are called from a button press. If one is played neither will play again.

What did I do wrong?

    public class ScanBarcodeActivity extends AppCompatActivity {
      MediaPlayer mp;


        @Override
        protected void onCreate(Bundle savedInstanceState) {
        //other stuff
            mp = new MediaPlayer();


    }

    public void playSuccessBeep() {
                try {
                    if (mp.isPlaying()) {
                        mp.stop();
                        mp.release();
                        mp = new MediaPlayer();
                    }

                    AssetFileDescriptor descriptor = getAssets().openFd("Success.wav");
                    mp.setDataSource(descriptor.getFileDescriptor(), descriptor.getStartOffset(), descriptor.getLength());
                    descriptor.close();

                    mp.prepare();
                    mp.setVolume(1f, 1f);
                    mp.setLooping(false);
                    mp.start();

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }


 public void playIncorrectBeep() {
        try {
            if (mp.isPlaying()) {
                mp.stop();
                mp.release();
                mp = new MediaPlayer();
            }

            AssetFileDescriptor descriptor = getAssets().openFd("Error.wav");
            mp.setDataSource(descriptor.getFileDescriptor(), descriptor.getStartOffset(), descriptor.getLength());
            descriptor.close();

            mp.prepare();
            mp.setVolume(1f, 1f);
            mp.setLooping(false);


            mp.start();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    }

Answer 1

It seems like you are calling start before the mp is prepared. Just change your

        mp.prepare();
        mp.setVolume(1f, 1f);
        mp.setLooping(false);
        mp.start();

to below

        mp.prepare();
         mp.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
        @Override
        public void onPrepared(MediaPlayer mp) {
           mp.setVolume(1f, 1f);
           mp.setLooping(false);
           mp.start(); 
        }
    });

ALso you are stopping and releasing media player only if it is playing. So change this

        if (mp.isPlaying()) {
                    mp.stop();
                    mp.release();
                    mp = new MediaPlayer();
                }

to

         if (mp.isPlaying()) {
                    mp.stop();
                }
          if(mp!=null){
                     mp.release();
                    mp = new MediaPlayer();
               }

Answer 2

Remove if(MP.isPlaying) and replace

            mp.stop();
            mp.release();
            mp = new MediaPlayer();

to

            mp.stop();
            mp.reset()