在android音板中，如何在单击另一个声音后停止播放声音？

Question

How do I modify this so that if one sound is playing already and another is clicked on, the previous stops playing and the newly selected starts? Thanks everyone for their help in advance. (this is not all the code just the most important)

public class newBoard extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.main);

    Toast.makeText(this, "Thank you for using this App.", Toast.LENGTH_LONG).show();

    // ads - load request to display
    AdView layout = (AdView)this.findViewById(R.id.adView);

    // ads - load display with an ad
    AdRequest adRequest = new AdRequest();
    adRequest.setTesting(true);

    layout.loadAd(adRequest);

    // import sound files
    final MediaPlayer sound01 = MediaPlayer.create(this, R.raw.sound01);
    final MediaPlayer sound02 = MediaPlayer.create(this, R.raw.sound02);
    final MediaPlayer sound03 = MediaPlayer.create(this, R.raw.sound03);
    final MediaPlayer sound04 = MediaPlayer.create(this, R.raw.sound04);
    final MediaPlayer sound05 = MediaPlayer.create(this, R.raw.sound05);
    final MediaPlayer sound06 = MediaPlayer.create(this, R.raw.sound06);
    final MediaPlayer sound07 = MediaPlayer.create(this, R.raw.sound07);
    final MediaPlayer sound08 = MediaPlayer.create(this, R.raw.sound08);
    final MediaPlayer sound09 = MediaPlayer.create(this, R.raw.sound09);
    final MediaPlayer sound10 = MediaPlayer.create(this, R.raw.sound10);
    final MediaPlayer sound11 = MediaPlayer.create(this, R.raw.sound11);
    final MediaPlayer sound12 = MediaPlayer.create(this, R.raw.sound12);
    final MediaPlayer sound13 = MediaPlayer.create(this, R.raw.sound13);
    final MediaPlayer sound14 = MediaPlayer.create(this, R.raw.sound14);
    final MediaPlayer sound15 = MediaPlayer.create(this, R.raw.sound15);
    final MediaPlayer sound16 = MediaPlayer.create(this, R.raw.sound16);
    final MediaPlayer sound17 = MediaPlayer.create(this, R.raw.sound17);
    final MediaPlayer sound18 = MediaPlayer.create(this, R.raw.sound18);
    final MediaPlayer sound19 = MediaPlayer.create(this, R.raw.sound19);
    final MediaPlayer sound20 = MediaPlayer.create(this, R.raw.sound20);
    final MediaPlayer sound21 = MediaPlayer.create(this, R.raw.sound21);
    final MediaPlayer sound22 = MediaPlayer.create(this, R.raw.sound22);
    final MediaPlayer sound23 = MediaPlayer.create(this, R.raw.sound23);
    final MediaPlayer sound24 = MediaPlayer.create(this, R.raw.sound24);
    final MediaPlayer sound25 = MediaPlayer.create(this, R.raw.sound25);

    // play sound files on clicks
    Button s01 = (Button) findViewById(R.id.button01); 
    s01.setText(this.getString(R.string.quote01));
    s01.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                sound01.prepare();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            sound01.start();                
            }

    });
    registerForContextMenu(s01);

    Button s02 = (Button) findViewById(R.id.button02); 
    s02.setText(this.getString(R.string.quote02));
    s02.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                sound02.prepare();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            sound02.start();
        }
    });
    registerForContextMenu(s02);

    Button s03 = (Button) findViewById(R.id.button03); 
    s03.setText(this.getString(R.string.quote03));
    s03.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                sound03.prepare();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            sound03.start();
        }
    });
    registerForContextMenu(s03);

    Button s04 = (Button) findViewById(R.id.button04); 
    s04.setText(this.getString(R.string.quote04));
    s04.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                sound04.prepare();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            sound04.start();
        }
    });
    registerForContextMenu(s04);

    Button s05 = (Button) findViewById(R.id.button05); 
    s05.setText(this.getString(R.string.quote05));
    s05.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                sound05.prepare();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            sound05.start();
        }
    });
    registerForContextMenu(s05);

    Button s06 = (Button) findViewById(R.id.button06); 
    s06.setText(this.getString(R.string.quote06));
    s06.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            try {
                sound06.prepare();
            } catch (IllegalStateException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            sound06.start();
        }
    });
    registerForContextMenu(s06);

Answer 1

Use a object member variable to hold on to your currently playing sound so that you can call stop() and don't forget to null check it. Don't forget to release() your MediaPlayer object once you leave your activity.

The following is probably a better design: move all your audio files to your assets directory and put the file name in the button's tag, use the same click event handler to get the state of the one MediaPlayer object, stop it if its currently playing, set the new file to play from the button's tag and play the file. This will reduce your duplicate code significantly.

Answer 2

Use a single MediaPlayer instance. Yours is going to fail on most devices as it is anyway for allocating to many instances of MediaPlayer . Also, repetitious code is bad. Bad bad:

public class NewBoard extends Activity {
    private MediaPlayer player;
    private Resources res;

    private int buttonIds = { R.id.button01, R.id.button02, R.id.button03,
                              R.id.button04, R.id.button05, R.id.button06,
                              R.id.button07, R.id.button08, R.id.button09,
                              R.id.button10, R.id.button11, R.id.button12,
                              R.id.button13, R.id.button14, R.id.button15,
                              R.id.button16, R.id.button16, R.id.button17,
                              R.id.button18, R.id.button19, R.id.button20,
                              R.id.button21, R.id.button22, R.id.button23,
                              R.id.button24, R.id.button25 };

    private int soundIds =  { R.raw.sound01, R.raw.sound02, R.raw.sound03,
                              R.raw.sound04, R.raw.sound05, R.raw.sound06,
                              R.raw.sound07, R.raw.sound08, R.raw.sound09,
                              R.raw.sound10, R.raw.sound11, R.raw.sound12,
                              R.raw.sound13, R.raw.sound14, R.raw.sound15,
                              R.raw.sound16, R.raw.sound16, R.raw.sound17,
                              R.raw.sound18, R.raw.sound19, R.raw.sound20,
                              R.raw.sound21, R.raw.sound22, R.raw.sound23,
                              R.raw.sound24, R.raw.sound25 };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);

        //Kill this with fire -- just an unnecessary user annoyance.
        Toast.makeText(this, 
            "Thank you for using this App.", Toast.LENGTH_LONG).show();

        AdView layout = (AdView)findViewById(R.id.adView);
        AdRequest adRequest = new AdRequest();
        adRequest.setTesting(true);
        layout.loadAd(adRequest);

        player = new MediaPlayer();
        res = getResources();

        for(int i = 0, n = buttonIds.length(); i < n; i++) {
            Button button = (Button)findViewById(buttonIds[i]);
            button.setOnClickListener(new SoundClickListener(soundIds[i]));
        }
    }

    private class SoundClickListener implements OnClickListener {
        private int id;

        public SoundClickListener(int soundId) {
            id = soundId;
        }

        public void onClick(View v) {
            player.reset();
            player.setDataSource(
                res.openRawResourceFd(id).getFileDescriptor());
            player.prepare();
            player.start();
        }
    }
}

Something like this. May or may not compile as is. Also, as commented, kill the Toast with fire -- that's just annoying.