update UI from BroadCastReceiver

Question

How can I update the main thread from a BroadCastReceiver. I have a BroadCastReceiver which receives a string and I need to set the text for a textview on my MainActivity, when I do findViewById(R.id.textView); on the onReceive method it returns null.

Here is my onCreate for the MainActivity.

public class MainActivity extends Activity {

......

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

IntentFilter broadcastFilter = new IntentFilter(ResponseReceiver.LOCAL_ACTION); 
receiver = new ResponseReceiver();
LocalBroadcastManager localBroadcastManager =   LocalBroadcastManager.getInstance(this);
localBroadcastManager.registerReceiver(receiver, broadcastFilter);

Intent msgIntent = new Intent(MainActivity.this, IntentService.class);
msgIntent.putExtra(StockDataIntentService.PARAM_IN_MSG, getResources().getString(R.string.url));
      startService(msgIntent);

    }

public class ResponseReceiver extends BroadcastReceiver {

 public static final String LOCAL_ACTION =   "com.mypackage.ALL_DONE";
 private Handler handler;

 @Override
 public void onReceive(Context context, Intent intent) {
   String text =intent.getStringExtra(IntentService.PARAM_OUT_MSG);
   TextView txtError = (TextView) findViewById(R.id.error);
      }
  }

OP for this question was having exact same issue, the accepted answer explains to use a handler etc.. But reading the comments on the answer explain the BroadastReceiver runs on the main thread so there is no reason to use a handler. How come I am unable to set the text on the text view ?

score 1 · Accepted Answer · answered Apr 26 '15 at 02:58

when I do findViewById(R.id.textView); on the onReceive method it returns null.

Because currently not calling setContentView method in onCreate method of Activity to set layout for current Activity

So, call setContentView in onCreate by passing layout it in which error TextView available

update UI from BroadCastReceiver

1 Answers1