Restarting an activity in Receiver

Question

I'm developing an app that uses SMS to receive and store data into database. Also, I have an activity that shows the result of a query from database. Now I want, if the this special activity is open and a new message arrives some code in sms-receiver restart this activity and if this activity was not open then nothing would happen.

Answer 1

You could register a BroadcastReceiver in your activity which performs the refresh of your activity:

public class YourActivity extends Activity {

    private final BroadcastReceiver myReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
           // refresh UI or finish activity and start again
        }
    };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...
        IntentFilter filter = new IntentFilter("ACTION_REFRESH_UI");
        registerReceiver(myReceiver, filter);
    }

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

        unregisterReceiver(myReceiver);
    }
}

Send the broadcast whenever a new message has been stored into the database:

Intent intent = new Intent();
intent.setAction("ACTION_REFRESH_UI");
sendBroadcast(intent);

You could also add a content observer for the database that gets notified about changes and which send the broadcast (see this example for more).