CODEWITHSUNDEEP
androidservice
Ankur Gupta
Ankur Gupta

Reputation: 410

Service object not getting initialised/ not calling onServiceCreated

I'm making a music player app. When I click list item in SongsFragment.java it sends intent to PlayerActivity.java with the song position. The musicSrv is null always. I looked for Activity lifecyle on google and figured out it has something to do with this. Since I'm beginner so couldn't apply that.

SongsFragment:

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
    //musicSrv.setSong(position);
    //musicSrv.playSong();
    Intent intent = new Intent(getContext(), PlayerActivity.class);
    intent.putExtra("pos", position);
    startActivity(intent);
}

In PlayerActivity.java:

public class PlayerActivity extends AppCompatActivity {
private MusicService musicSrv;
private Intent playIntent;
private boolean musicBound=false;
private static final String POS = "pos";
private int passedPos;



protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Bundle extras = getIntent().getExtras();
    passedPos = extras.getInt("pos",0);
    musicSrv.setSong(passedPos);
    musicSrv.playSong();

    setContentView(R.layout.activity_player);
}


ServiceConnection musicConnection = new ServiceConnection(){

    @Override
    public void onServiceConnected(ComponentName name, IBinder service) {
        MusicService.MusicBinder binder = (MusicService.MusicBinder)service;
        //Get service
        musicSrv = binder.getService();
        //Pass list
        ArrayList<Song> songs = ((DataFetcher)getApplicationContext()).songList;
        musicSrv.setList(songs);
        musicBound = true;
    }

    @Override
    public void onServiceDisconnected(ComponentName name) {
        musicBound = false;
    }
};

@Override
public void onStart() {
    super.onStart();
    if(playIntent==null) {
        playIntent = new Intent(this,(Class)MusicService.class);
        bindService(playIntent,musicConnection, Context.BIND_AUTO_CREATE);
        startService(playIntent);
    }
}

@Override
public void onDestroy() {
    stopService(playIntent);
    musicSrv=null;
    super.onDestroy();
}

}

Error: I get "Attempt to invoke virtual method 'void services.MusicService.setSong(int)' on a null object reference"

Upvotes: 0

Views: 80

Answers (1)

CommonsWare
CommonsWare

Reputation: 1006644

First, onCreate() is called before onStart(). musicSrv will be null, because you have not called bindService() yet.

Second, bindService() itself is asynchronous. It will be some time later before your onServiceConnected() method is called.

You cannot use musicSrv until you assign that field a value, and you cannot do that until inside of onServiceConnected() at the earliest.

So, move your calls related to musicSrv into onServiceConnected() or some later event, after you know that musicSrv should be ready.

Also, do not call bindService() directly, as that will get you in trouble with configuration changes with this activity. Call bindService() (and, later, unbindService()) using the Application object (e.g., getApplicationContext().bindService()).

Upvotes: 1

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