如何停止已经播放的声音，并立即开始另一个

Question

当的声音，先前选择正在播放的用户，我怎么能阻止这种声音，并立即打新选定的声音？我到目前为止的代码只能停止新的声音，但用户必须以发挥它再次选择声音。

public class MainActivity extends Activity { 
    public MediaPlayer mediaPlayer = null; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     Button a = (Button) findViewById(R.id.First); 
     a.setOnClickListener(new OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       if (mediaPlayer == null) { 
        mediaPlayer = MediaPlayer.create(MainActivity.this, R.raw.firstsound); 
        mediaPlayer.stop(); 
       } 
       else { 
        mediaPlayer.start(); 
        mediaPlayer = null; 
       } 
      } 
     } 
     ); 
     Button b = (Button) findViewById(R.id.Second); 
     b.setOnClickListener(new OnClickListener() { 
      @Override 
      public void onClick(View v) { 
       if (mediaPlayer == null) { 
        mediaPlayer = MediaPlayer.create(MainActivity.this, R.raw.secondsound); 
        mediaPlayer.stop(); 
       } 
       else { 
        mediaPlayer.start(); 
        mediaPlayer = null; 
       } 
      } 
     } 
     ); 

我制作了超过30种声音的音板，如果有帮助的话。我需要对我的代码进行什么（轻微的假设）更改？任何帮助将不胜感激！

Answer 1

public class MainActivity extends Activity { 

    public MediaPlayer mediaPlayer = null; 
    public Boolean playing=false; 
    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     Button a = (Button) findViewById(R.id.First); 
     a.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View v) { 

       (playing)mediaPlayer.stop(); 
       mediaPlayer = MediaPlayer.create(MainActivity.this, R.raw.firstsound); 
       mediaPlayer.start(); 
          playing=true; 
      } 

     }); 

     Button b = (Button) findViewById(R.id.Second); 
     b.setOnClickListener(new OnClickListener() { 

      @Override 
      public void onClick(View v) { 
       (playing)mediaPlayer.stop(); 
       mediaPlayer = MediaPlayer.create(MainActivity.this, R.raw.firstsound); 
       mediaPlayer.start(); 
          playing=true; 
      } 
     }); 
    } 
}