Question

I’m working on an Android project that consists of several different Activities all associated with the same Application. We have some common tasks coded in the Application so that we don’t have to duplicate them, and one of these tasks is regularly verifying a TCP connection to a dedicated server — a heartbeat, I suppose.

If it’s detected that the connection to the server is lost, I need to notify the user and I’d like to do this in a way that doesn’t require me to check all the possible activities to see which is currently “on top”.

Is there a way to call runOnUiThread() on whatever activity may be on the UI thread without knowing it explicitly??

Thanks,
R.

Answer 1

You can notify your Activities by sending Intent and registering BroadcastReceiver in each Activity you want to be notified.

service or application can be your context:

Intent i = new Intent("MY_ACTION_FROM_SERVICE_STRING");
context.sendBroadcast(i);

activity:

public class MyActivity extends Activity {
    private ActivityBroadcastReceiver recvr;

    public void onReceiveCommand() {
        //do something
    }
    @Override
    public void onCreate(Bundle b) {
        super.onCreate(b);
        recvr = new ActivityBroadcastReceiver(this);
        this.registerReceiver(recvr,
            new IntentFilter("MY_ACTION_FROM_SERVICE_STRING"));
    }
}

receiver:

public class ActivityBroadcastReceiver extends BroadcastReceiver {
    private MyActivity target;
    public ActivityBroadcastReceiver(MyActivity target) {
        this.target = target;
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        target.onReceiveCommand();
    }
}