在整个活动中改变音量

Question

So here I am creating a Music Service class

public class MusicService extends Service implements MediaPlayer.OnErrorListener {

private final IBinder mBinder = new ServiceBinder();
MediaPlayer mPlayer;
private int length = 0;

public MusicService() {
}

public class ServiceBinder extends Binder {
    MusicService getService() {
        return MusicService.this;
    }
}

@Override
public IBinder onBind(Intent arg0) {
    return mBinder;
}

@Override
public void onCreate() {
    super.onCreate();

    mPlayer = MediaPlayer.create(this, R.raw.game_music);
    mPlayer.setOnErrorListener(this);

    if (mPlayer != null) {
        mPlayer.setLooping(true);
        mPlayer.setVolume(100, 100);
    }


    mPlayer.setOnErrorListener(new OnErrorListener() {

        public boolean onError(MediaPlayer mp, int what, int
                extra) {

            onError(mPlayer, what, extra);
            return true;
        }
    });
}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    mPlayer.start();
    return START_STICKY;
}


public void pauseMusic() {
    if (mPlayer.isPlaying()) {
        mPlayer.pause();
        length = mPlayer.getCurrentPosition();

    }
}

public void resumeMusic() {
    if (mPlayer.isPlaying() == false) {
        mPlayer.seekTo(length);
        mPlayer.start();
    }
}

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

@Override
public void onDestroy() {
    super.onDestroy();
    if (mPlayer != null) {
        try {
            mPlayer.stop();
            mPlayer.release();
        } finally {
            mPlayer = null;
        }
    }
}

public boolean onError(MediaPlayer mp, int what, int extra) {

    Toast.makeText(this, "music player failed", Toast.LENGTH_SHORT).show();
    if (mPlayer != null) {
        try {
            mPlayer.stop();
            mPlayer.release();
        } finally {
            mPlayer = null;
        }
    }
    return false;
}

}

Then, in my main game activity I start out the code with

public class Gameview extends AppCompatActivity {
/**
 * Whether or not the system UI should be auto-hidden after
 * {@link #AUTO_HIDE_DELAY_MILLIS} milliseconds.
 */
private boolean mIsBound = false;
private MusicService mServ;
private ServiceConnection Scon =new ServiceConnection(){

    public void onServiceConnected(ComponentName name, IBinder
            binder) {
        /*mServ = ((MusicService.ServiceBinder binder).getService());*/
        MusicService.ServiceBinder sb = (MusicService.ServiceBinder) binder;
        mServ = sb.getService();
    }

    public void onServiceDisconnected(ComponentName name) {
        mServ = null;
    }
};

void doBindService(){
    bindService(new Intent(this,MusicService.class),
            Scon, Context.BIND_AUTO_CREATE);
    mIsBound = true;
}

void doUnbindService()
{
    if(mIsBound)
    {
        unbindService(Scon);
        mIsBound = false;
    }
}

Then, in the main game activities onCreate, I bind the service to the activity with

    doBindService();
    Intent music = new Intent();
    music.setClass(this,MusicService.class);
    startService(music);

NOW, the game works by allowing the user to click on planets and when they do that, it redirects them to a different activity with the picture of the planet. As it stands, music will continue playing and looping through the game when users click on planets and then return to the activity it is created in (so this part is working perfectly). MY PROBLEM IS THIS: I want to have the music either pause or reduce in volume when a user clicks on the planet and return to normal when going back to the main game view. My problem is I don't know how to inherit my MusicService object from these planet-views in order to manipulate it.. I tried messing around with something like this the the planet's onCreate, but had no luck

MusicService.ServiceBinder sb = (MusicService.ServiceBinder) binder;
mServ = sb.getService()

How can I manipulate my MusicService object outside of the game's main activity???

Answer 1

public and static modifiers makes an object or a variable usable from other classes.

Simply declare MusicService object as public static , and call it in the onCreate method of the planet activity.

Hope it helps!