media player crash after back button is pressed and open app again

Question

Well my app have a menu when it starts, there you hit a button to begin with the app. As soon as it starts a mediaplayer start playing, but if I click back button, hit the button to start app again and then click button to stop music the app crashes. heres the code for that. It crashed at a cellphone but in emulator it works fine. Any comment will be appreciated. Thanks

int cancion = 1, cancion1 = 1;
MediaPlayer song, song1, song2, song3, song4;
if (cancion == 1)
    {
        song1.start();
        playing = true;
        song1.setLooping(true);
        song = song1;
    }
music.setOnLongClickListener(new View.OnLongClickListener() {

    public boolean onLongClick(View view) {
            song.pause();
            song.seekTo(0);
            playing = false;
            cancion = cancion+1;

            if (cancion == 5)
            {
                cancion = 1;
            }
            if (cancion == 1)
            {
                song1.start();
                playing = true;
                song1.setLooping(true);
                song = song1;
            }
            else if (cancion == 2)
            {
                song2.start();
                playing = true;
                song2.setLooping(true);
                song = song2;
            }
            else if (cancion == 3)
            {
                song3.start();
                playing = true;
                song3.setLooping(true);
                song = song3;
            }
            else if (cancion == 4)
            {
                song4.start();
                playing = true;
                song4.setLooping(true);
                song = song4;
            }

        return true;
    }
});
    music.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {

            if (!playing)
            {
                song.start();
                playing = true;
            }

            else
            {
                song.pause();
                song.seekTo(0);
                playing = false;
                cancion1 = 2;
            }
        }
});
@Override
protected void onResume() {
    super.onResume();
    if(!song.isPlaying() && cancion1 != 2)
    {
        song.start();
        playing = true;
    }
}
@Override
public void onPause(){
    super.onPause();
    if(song.isPlaying())
    {
        song.pause();
        song.seekTo(0);
        playing = false;
    }
}

LogCat:

04-22 22:12:47.151: W/ActivityNative(12915): send ACTIVITY_IDLE_TRANSACTION 04-22 22:12:47.541: W/dalvikvm(12915): threadid=1: thread exiting with uncaught exception (group=0x400207d8) 04-22 22:12:47.551: E/AndroidRuntime(12915): FATAL EXCEPTION: main 04-22 22:12:47.551: E/AndroidRuntime(12915): java.lang.NullPointerException 04-22 22:12:47.551: E/AndroidRuntime(12915): at com.try.player.DragActivity$5.onClick(DragActivity.java:1772) 04-22 22:12:47.551: E/AndroidRuntime(12915): at android.view.View.performClick(View.java:2408) 04-22 22:12:47.551: E/AndroidRuntime(12915): at android.view.View$PerformClick.run(View.java:8816) 04-22 22:12:47.551: E/AndroidRuntime(12915): at android.os.Handler.handleCallback(Handler.java:587) 04-22 22:12:47.551: E/AndroidRuntime(12915): at android.os.Handler.dispatchMessage(Handler.java:92) 04-22 22:12:47.551: E/AndroidRuntime(12915): at android.os.Looper.loop(Looper.java:123) 04-22 22:12:47.551: E/AndroidRuntime(12915): at android.app.ActivityThread.main(ActivityThread.java:4633) 04-22 22:12:47.551: E/AndroidRuntime(12915): at java.lang.reflect.Method.invokeNative(Native Method) 04-22 22:12:47.551: E/AndroidRuntime(12915): at java.lang.reflect.Method.invoke(Method.java:521) 04-22 22:12:47.551: E/AndroidRuntime(12915): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858) 04-22 22:12:47.551: E/AndroidRuntime(12915): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 04-22 22:12:47.551: E/AndroidRuntime(12915): at dalvik.system.NativeStart.main(Native Method)

Answer 1

Change your onPause() to release all the MediaPlayer Objects instead of trying to restart song currently playing.

Something like this:

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

    song.release();
    song1.release();
    //and so on

}