Android iBeacon Library ranging api

Question

I'm using Android IBeacon Library and trying to get the number of iBeacons in the region. Using the ranging api I get the devices count. This count keeps on changing from 0 to n even when all iBeacons and my phone is still. Also when I try to get the details of the devices I get the following exception. What's causing the exception. When I tried debugging I see the datas are not null.

04-14 11:26:37.203  11754-11883/com.test.ibeacon E/AndroidRuntime﹕ FATAL EXCEPTION: IntentService[IBeaconIntentProcessor]
Process: com.test.ibeacon, PID: 11754
java.util.NoSuchElementException
        at java.util.ArrayList$ArrayListIterator.next(ArrayList.java:576)
        at com.test.ibeacon.MainActivity$1.didRangeBeaconsInRegion(MainActivity.java:115)
        at com.radiusnetworks.ibeacon.IBeaconIntentProcessor.onHandleIntent(IBeaconIntentProcessor.java:73)
        at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:65)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:136)
        at android.os.HandlerThread.run(HandlerThread.java:61)

My Code:

iBeaconManager.setRangeNotifier(new RangeNotifier() {
        @Override
        public void didRangeBeaconsInRegion(Collection<IBeacon> iBeacons, Region region) {
            Log.d(LOG_TAG,"No of devices == "+iBeacons.size());
            if (iBeacons.size() > 0) {
                Log.i(LOG_TAG, "The first iBeacon I see is about "+iBeacons.iterator().next().getAccuracy()+" meters away.");
            }
            Iterator<IBeacon> iterator = iBeacons.iterator();
            while (iterator.hasNext()) {
                Log.d(LOG_TAG,"Major = "+(iterator.next()).getMajor()+" Minor = "+(iterator.next()).getMinor());
            }
        }
    });

    try {
        iBeaconManager.startRangingBeaconsInRegion(new Region("myUniqueId", null, null, null)); //I'm specifying the UniqueId.
    } catch (RemoteException e) {   }

Answer 1

Are you supplying the proximityUUID of your iBeacon when starting ranging? My Code looks like this:

String proximityUUID = "xxxxxx";
iBeaconManager.startRangingBeaconsInRegion(new Region("myRangingUniqueId", proximityUUID, null, null));

Then in didRangeBeaconsInRegionenter :

if (iBeacons.size() > 0) {
    for (IBeacon iBeacon : iBeacons) {                              
        logToDisplay(String.format("( %.2f m ) %d", iBeacon.getAccuracy(), iBeacon.getProximity()));
    }
}

Here you should get the accuracy and proximity of each seen iBeacon.

Answer 2

I suspect you have more than one Region being ranged, and the second region is giving you an empty array. You can fix the problem by moving your iteration inside the if statement. Like this:

    @Override
    public void didRangeBeaconsInRegion(Collection<IBeacon> iBeacons, Region region) {
        Log.d(LOG_TAG,"No of devices == "+iBeacons.size());
        if (iBeacons.size() > 0) {
            Log.i(LOG_TAG, "The first iBeacon I see is about "+iBeacons.iterator().next().getAccuracy()+" meters away.");
            Iterator<IBeacon> iterator = iBeacons.iterator();
            while (iterator.hasNext()) {
                Log.d(LOG_TAG,"Major = "+(iterator.next()).getMajor()+" Minor = "+(iterator.next()).getMinor());
            }
        }
    }