Android “Only the original thread that created a v

Question

I've built a simple music player in Android. The view for each song contains a SeekBar, implemented like this:

public class Song extends Activity implements OnClickListener,Runnable {
    private SeekBar progress;
    private MediaPlayer mp;

    // ...

    private ServiceConnection onService = new ServiceConnection() {
          public void onServiceConnected(ComponentName className,
            IBinder rawBinder) {
              appService = ((MPService.LocalBinder)rawBinder).getService(); // service that handles the MediaPlayer
              progress.setVisibility(SeekBar.VISIBLE);
              progress.setProgress(0);
              mp = appService.getMP();
              appService.playSong(title);
              progress.setMax(mp.getDuration());
              new Thread(Song.this).start();
          }
          public void onServiceDisconnected(ComponentName classname) {
              appService = null;
          }
    };

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.song);

        // ...

        progress = (SeekBar) findViewById(R.id.progress);

        // ...
    }

    public void run() {
    int pos = 0;
    int total = mp.getDuration();
    while (mp != null && pos<total) {
        try {
            Thread.sleep(1000);
            pos = appService.getSongPosition();
        } catch (InterruptedException e) {
            return;
        } catch (Exception e) {
            return;
        }
        progress.setProgress(pos);
    }
}

This works fine. Now I want a timer counting the seconds/minutes of the progress of the song. So I put a TextView in the layout, get it with findViewById() in onCreate(), and put this in run() after progress.setProgress(pos):

String time = String.format("%d:%d",
            TimeUnit.MILLISECONDS.toMinutes(pos),
            TimeUnit.MILLISECONDS.toSeconds(pos),
            TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(
                    pos))
            );
currentTime.setText(time);  // currentTime = (TextView) findViewById(R.id.current_time);

But that last line gives me the exception:

android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

Yet I'm doing basically the same thing here as I'm doing with the SeekBar - creating the view in onCreate, then touching it in run() - and it doesn't give me this complaint.

Answer 1

I was facing a similar problem and none of the methods mentioned above worked for me. In the end, this did the trick for me:

Device.BeginInvokeOnMainThread(() =>
    {
        myMethod();
    });

I found this gem here.

Answer 2

I see that you have accepted @providence's answer. Just in case, you can also use the handler too! First, do the int fields.

    private static final int SHOW_LOG = 1;
    private static final int HIDE_LOG = 0;

Next, make a handler instance as a field.

    //TODO __________[ Handler ]__________
    @SuppressLint("HandlerLeak")
    protected Handler handler = new Handler()
    {
        @Override
        public void handleMessage(Message msg)
        {
            // Put code here...

            // Set a switch statement to toggle it on or off.
            switch(msg.what)
            {
            case SHOW_LOG:
            {
                ads.setVisibility(View.VISIBLE);
                break;
            }
            case HIDE_LOG:
            {
                ads.setVisibility(View.GONE);
                break;
            }
            }
        }
    };

Make a method.

//TODO __________[ Callbacks ]__________
@Override
public void showHandler(boolean show)
{
    handler.sendEmptyMessage(show ? SHOW_LOG : HIDE_LOG);
}

Finally, put this at onCreate() method.

showHandler(true);

Answer 3

This happened to my when I called for an UI change from a doInBackground from Asynctask instead of using onPostExecute.

Dealing with the UI in onPostExecute solved my problem.

Answer 4

I was working with a class that did not contain a reference to the context. So it was not possible for me to use runOnUIThread(); I used view.post(); and it was solved.

timer.scheduleAtFixedRate(new TimerTask() {

    @Override
    public void run() {
        final int currentPosition = mediaPlayer.getCurrentPosition();
        audioMessage.seekBar.setProgress(currentPosition / 1000);
        audioMessage.tvPlayDuration.post(new Runnable() {
            @Override
            public void run() {
                audioMessage.tvPlayDuration.setText(ChatDateTimeFormatter.getDuration(currentPosition));
            }
        });
    }
}, 0, 1000);

Answer 5

Use this code, and no need to runOnUiThread function:

private Handler handler;
private Runnable handlerTask;

void StartTimer(){
    handler = new Handler();   
    handlerTask = new Runnable()
    {
        @Override 
        public void run() { 
            // do something  
            textView.setText("some text");
            handler.postDelayed(handlerTask, 1000);    
        }
    };
    handlerTask.run();
}

Answer 6

When using AsyncTask Update the UI in onPostExecute method

    @Override
    protected void onPostExecute(String s) {
   // Update UI here

     }