Incremental hits on didEnterRegion when app closed then re-opened

Expected behavior

Open app and start monitoring, it should detect a beacon and didEnterRegion should hit once. (I am using only 1 beacon)

Actual behavior

Open app monitoring starts, didEnterRegion hits 1 time on first run but after unbind and destroyed activity then open app again didEnterRegion hits 2 times. (repeat same process then hits goes on increasing from 1, 2 , 3 ,4 , … )

Steps to reproduce this behavior

• Open app monitoring starts, didEnterRegion hits 1 time on first run
• Close the app (unbind and destroyed activity)
• Open app again didEnterRegion now hits 2 times. (repeat same process then hits goes on increasing from 1, 2 , 3 ,4 , … )

Mobile device model and OS version

• android 9.0 (Oneplus 6)

Android Beacon Library version

• 2.15.4 (also could reproduce on 2.15.2)

My code is attached and below are onCreate() and onDestroy() code snippets:

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.i(TAG, "OnCreate() called.");
        setContentView(R.layout.activity_main);
        beaconManager = BeaconManager.getInstanceForApplication(this);
        beaconManager.getBeaconParsers().add(new BeaconParser().setBeaconLayout("m:2-3=0215,i:4-19,i:20-21,i:22-23,p:24-24"));

 
        if (!beaconManager.isBound(this)) {
            Notification.Builder builder = new Notification.Builder(MainActivity.this);
            builder.setSmallIcon(R.mipmap.ic_launcher);
            builder.setContentTitle("Scanning for Beacons");
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                NotificationChannel channel = new NotificationChannel(TAG,
                        "BeaconPOC", NotificationManager.IMPORTANCE_HIGH);
                channel.setDescription("BeaconPOC");
                NotificationManager notificationManager = (NotificationManager) getSystemService(
                        Context.NOTIFICATION_SERVICE);
                notificationManager.createNotificationChannel(channel);

                PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                        new Intent(this, MainActivity.class), PendingIntent.FLAG_UPDATE_CURRENT);

                builder.setContentIntent(contentIntent);
                builder.setChannelId(channel.getId());
            }
            beaconManager.enableForegroundServiceScanning(builder.build(), FOREGROUND_NOTIFICATION_ID);
            beaconManager.setEnableScheduledScanJobs(false);
            beaconManager.setRegionStatePersistenceEnabled(false);
            beaconManager.bind(this);
            Log.i(TAG, "Beacon service just got bound");
            backgroundPowerSaver = new BackgroundPowerSaver(this);
        }
  }

  @Override
    protected void onDestroy() {
        super.onDestroy();
        stopRangingAndMonitoring();
        beaconManager.unbind(this);
        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        notificationManager.cancel(10001);
        beaconManager.disableForegroundServiceScanning();
    }
    
    @Override
    public void onBeaconServiceConnect() {
        Log.i(TAG, "onBeaconServiceConnect() : Connected.");
        beaconManager.addRangeNotifier(new RangeNotifier() {
            public void didRangeBeaconsInRegion(Collection<Beacon> beacons, Region region) {
                for (Beacon beacon : beacons) {
                    if (beacon.getDistance() < 5.0) {

                        try {
                            beaconManager.stopRangingBeaconsInRegion(region);

                            BeaconInfo beaconInfo = new BeaconInfo(beacon.getId1().toString(), Integer.parseInt(beacon.getId2().toString()), Integer.parseInt(beacon.getId3().toString()), beacon.getDistance());
                            beaconInfoList.add(beaconInfo);

                            mAdapter.notifyDataSetChanged();

                        } catch (RemoteException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        });


        beaconManager.addMonitorNotifier(new MonitorNotifier() {
            @Override
            public void didEnterRegion(Region region) {
                Log.i(TAG, "I just saw an beacon for the first time!");
                try {
                    Log.i(TAG, "Started Ranging");
                    beaconManager.startRangingBeaconsInRegion(new Region("uniqueId1", null, null, null));
                } catch (RemoteException e) {
                    e.printStackTrace();
                }

                Toast.makeText(MainActivity.this, "I see a Beacon entered.", Toast.LENGTH_LONG).show();

            }

            @Override
            public void didExitRegion(Region region) {
                Log.i(TAG, "I no longer see an beacon");
                Toast.makeText(MainActivity.this, "I see a Beacon exited.", Toast.LENGTH_LONG).show();

            }

            @Override
            public void didDetermineStateForRegion(int state, Region region) {

            }
        });

        try {
            stopRangingAndMonitoring();
            Log.i(TAG, "Started Monitoring.");
            beaconManager.startMonitoringBeaconsInRegion(new Region("uniqueId2", null, null, null));
        } catch (RemoteException e) {
            Log.i(TAG, e.toString());
        }
    }

    private void stopRangingAndMonitoring() {
        for (Region region : beaconManager.getMonitoredRegions()) {
            try {
                beaconManager.stopMonitoringBeaconsInRegion(region);
                Log.i(TAG, "Stop monitoring: " + region.toString());
            } catch (RemoteException e) {
            }
        }
        for (Region region : beaconManager.getRangedRegions()) {
            try {
                beaconManager.stopRangingBeaconsInRegion(region);
                Log.i(TAG, "Stop ranging: " + region.toString());
            } catch (RemoteException e) {
            }
        }
    }

MainActivity.txt

[davidgyoung]

Can you please show stopRangingAndMonitoring and where you start ranging and monitoring?

[davidgyoung]

Glad you found a fix that worked for you.

The rangeNotifiers and monitorNotifiers on BeaconManager are contained in a Set, so they will not allow duplicates. However, if you end up with two instances of your MainActivity (quite possible in Android depending on how you set up your AndroidManifest.xml or use Intents to start your activity), then you might end up with multiple notifiers. Clearing the notifiers is always the safest bet to avoid duplicates.