How to send notification if the app is at the background in android?

Issue

Currently I am working on bluetooth scan, that means I will keep scanning the device, if there is device nearby , I will show it on screen, however, if the app is at the background, I need to show notification to the user.

And now my working logic is like this, there is a main class that fire the scan service, the scan service job is to return a list of scanned device. And the main class job is to display/ process the result.

The code is like this:

Service

public class Detector extends Service implements IBeaconConsumer {

    protected static final String TAG = "RangingActivity";
    private IBeaconManager iBeaconManager;

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        iBeaconManager = IBeaconManager.getInstanceForApplication(this);
        iBeaconManager.bind(this);
        Log.d("test1","bind");
        return super.onStartCommand(intent, flags, startId);
    }
}

Main

private class DataUpdateReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent.getAction().equals("scanResult")) {
            ArrayList<IBeacon> beacons = (ArrayList<IBeacon>) intent.getSerializableExtra("beacons");

            for(IBeacon be : beacons){
                if (be.getProximityUuid().equals("ebefd083-70a2-47c8-9837-e7b5634df524")) {
                    if (be.getMajor() == 2) {
                        a_rssi = be.getRssi();
                    } else if (be.getMajor() == 1) {
                        b_rssi = be.getRssi();
                    }
                }
            }

            if(a_rssi > b_rssi) {
                Log.d("test1","at shop");
                //at shop,need case handling if more than 1 shop beacon
                showAd(R.drawable.offer1);

                if (timer != null)
                    timer.cancel();

                timer = null;
                timeCount = 0;

                Intent msg = new Intent("timerUpdate");
                msg.putExtra("timeCount", timeCount);
                sendBroadcast(msg);
            } else {
                Log.d("test1","at park");

                //at car park
                if (timer == null) {
                    timer = new Timer(true);
                    timer.schedule(new MyTimer(), 1000, 1000);
                }
            }

        }
    }
}

The problem is , if I need to add notification, does I need to move the process part code (which is in the main class) to service? How can I achieve it? Thanks

Solution

First you need to check if your application is in background. You can call below code on onPause() on every activity in your application:

/**
* Checks if the application is being sent in the background (i.e behind
* another application's Activity).
* 
* @param context the context
* @return <code>true</code> if another application will be above this one.
*/
public static boolean isApplicationSentToBackground(final Context context) {
 ActivityManager am = (ActivityManager)    context.getSystemService(Context.ACTIVITY_SERVICE);
 List<RunningTaskInfo> tasks = am.getRunningTasks(1);
 if (!tasks.isEmpty()) {
  ComponentName topActivity = tasks.get(0).topActivity;
  if (!topActivity.getPackageName().equals(context.getPackageName())) {
    return true;
  }
 }

 return false;
}

Add this line in your manifest file :

<uses-permission android:name="android.permission.GET_TASKS" />

For adding notification you can add this code :

private void addNotification(Context context, String message) {

 int icon = R.drawable.ic_launcher;
 long when = System.currentTimeMillis();
 String appname = context.getResources().getString(R.string.app_name);
 NotificationManager notificationManager = (NotificationManager) context
 .getSystemService(Context.NOTIFICATION_SERVICE);

 Notification notification;
 PendingIntent contentIntent = PendingIntent.getActivity(context, 0,
 new Intent(context, myactivity.class), 0);


 NotificationCompat.Builder builder = new NotificationCompat.Builder(
 context);
 notification = builder.setContentIntent(contentIntent)
 .setSmallIcon(icon).setTicker(appname).setWhen(0)
 .setAutoCancel(true).setContentTitle(appname)
 .setContentText(message).build();

 notificationManager.notify(0 , notification);

 }

Answered By - Siddharth_Vyas