播放另一个媒体播放器时停止MP3播放器

当我玩MP3播放器时我遇到了问题它播放得很好但是当我开始另一个活动并且回到播放器时，搜索栏和持续时间仍为0，因为当我在另一个活动中播放媒体播放器时我没有播放mp3文件我想要播放mp3停止我怎么能这样做

我的播放器代码

private MediaPlayer mediaPlayer;
public TextView songName, duration;
private double timeElapsed = 0, finalTime = 0;
private int forwardTime = 2000, backwardTime = 2000;
private Handler durationHandler = new Handler();
private SeekBar seekbar;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    final ActionBar bar = getActionBar();
    if (bar.isShowing()) {
        bar.hide();
    }
    //set the layout of the Activity
    setContentView(R.layout.activity_om1);

    //initialize views
    initializeViews();
}

public void initializeViews(){
    songName = (TextView) findViewById(R.id.songName);
    mediaPlayer = MediaPlayer.create(this, R.raw.om1);
    finalTime = mediaPlayer.getDuration();
    duration = (TextView) findViewById(R.id.songDuration);
    seekbar = (SeekBar) findViewById(R.id.seekBar);
    songName.setText("song");

    seekbar.setMax((int) finalTime);
    seekbar.setClickable(false);
     if (mediaPlayer.isPlaying()) {//check if a song is already playing
         mediaPlayer.pause();
         try {
             mediaPlayer.prepare();//get the mediaplayer reeady for playback
         } catch (IllegalStateException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         } catch (IOException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
     }else {
     }
 }   

// play mp3 song
public void play(View view) {
    mediaPlayer.start();
    timeElapsed = mediaPlayer.getCurrentPosition();
    seekbar.setProgress((int) timeElapsed);
    durationHandler.postDelayed(updateSeekBarTime, 100);
}

//handler to change seekBarTime
private Runnable updateSeekBarTime = new Runnable() {
    public void run() {
        //get current position
        timeElapsed = mediaPlayer.getCurrentPosition();
        //set seekbar progress
        seekbar.setProgress((int) timeElapsed);
        //set time remaing
        double timeRemaining = finalTime - timeElapsed;
        duration.setText(String.format("%d min, %d sec", TimeUnit.MILLISECONDS.toMinutes((long) timeRemaining), TimeUnit.MILLISECONDS.toSeconds((long) timeRemaining) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes((long) timeRemaining))));

        //repeat yourself that again in 100 miliseconds
        durationHandler.postDelayed(this, 100);
    }
};

// pause mp3 song
public void pause(View view) {
    mediaPlayer.pause();
}

// go forward at forwardTime seconds
public void forward(View view) {
    //check if we can go forward at forwardTime seconds before song endes
    if ((timeElapsed + forwardTime) <= finalTime) {
        timeElapsed = timeElapsed + forwardTime;

        //seek to the exact second of the track
        mediaPlayer.seekTo((int) timeElapsed);
    }
}

// go backwards at backwardTime seconds
public void rewind(View view) {
    //check if we can go back at backwardTime seconds after song starts
    if ((timeElapsed - backwardTime) > 0) {
        timeElapsed = timeElapsed - backwardTime;

        //seek to the exact second of the track
        mediaPlayer.seekTo((int) timeElapsed);
    }
}