从另一个类在MediaPlayer上调用暂停-Android Java

Question

I have a class named NowPlayingActivity and VideosActivity. Both are handled by a TabHost. At the start of the app, mediaplayer from NowPlayingActivity will play a song automatically. When I go to videos activity, there would be a list of videos available to play. What I want is to stop the song playing from NowPlayingActivity when I clicked an item from videosactivity so the song will stop at video play.

public void onItemClick(AdapterView parent, View v, int position, long id)
{
    NowPlayingActivity npa = new NowPlayingActivity();
    npa.pause();
    System.gc();
    videoColumnIndex = videoCursor.getColumnIndexOrThrow(
            MediaStore.Video.Media.DATA);
    videoCursor.moveToPosition(position);
    String filename = videoCursor.getString(videoColumnIndex);
    Log.i("FileName: ", filename);

    Intent intent = new Intent(Intent.ACTION_VIEW);
    Uri data = Uri.parse(filename);
    intent.setDataAndType(data, "video/*"); 
    startActivity(intent);
}

This is my code that starts and intent to play a selected video from the list, and play it on the gallery.

I tried creating a method pause from the NowPlayingActivity then call it on item click from videos activity.

public void pause(){

    if(mp.isPlaying()){
        if(mp!=null){
            mp.pause();
        }
    }
}

I don't know if this is possible but i can't think of any way but this.

EDIT:

Logcat
07-14 06:18:32.526: E/AndroidRuntime(979): FATAL EXCEPTION: main
07-14 06:18:32.526: E/AndroidRuntime(979): java.lang.NullPointerException
07-14 06:18:32.526: E/AndroidRuntime(979):  at com.example.prismmediaplayer.NowPlayingActivity.pause(NowPlayingActivity.java:410)
07-14 06:18:32.526: E/AndroidRuntime(979):  at com.example.prismmediaplayer.VideosActivity$1.onItemClick(VideosActivity.java:59)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.widget.AdapterView.performItemClick(AdapterView.java:298)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.widget.AbsListView.performItemClick(AbsListView.java:1086)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.widget.AbsListView$PerformClick.run(AbsListView.java:2855)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.widget.AbsListView$1.run(AbsListView.java:3529)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.os.Handler.handleCallback(Handler.java:615)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.os.Handler.dispatchMessage(Handler.java:92)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.os.Looper.loop(Looper.java:137)
07-14 06:18:32.526: E/AndroidRuntime(979):  at android.app.ActivityThread.main(ActivityThread.java:4745)
07-14 06:18:32.526: E/AndroidRuntime(979):  at java.lang.reflect.Method.invokeNative(Native Method)
07-14 06:18:32.526: E/AndroidRuntime(979):  at java.lang.reflect.Method.invoke(Method.java:511)
07-14 06:18:32.526: E/AndroidRuntime(979):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
07-14 06:18:32.526: E/AndroidRuntime(979):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
07-14 06:18:32.526: E/AndroidRuntime(979):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

Put the MediaPlayer in your host activity. Then you can call your actions from either NowPlayingActivity or VideosActivity