Android app keeps crashing at list.get(1)

BLE Beacons
1

Hi!

Yesterday, my app worked perfectly. Today, when I open it to use it again, the app keeps crashing at this line (last line of the code):

// Defining the beacons to look out for //
private static final Map<String, List<String>> PLACES_BY_BEACONS;
// beacon defintion
private BeaconManager beaconManager;
private Region region;

// TODO: replace "<major>:<minor>" strings to match your own beacons.
static {
    Map<String, List<String>> placesByBeacons = new HashMap<>();
    placesByBeacons.put("56738:65449", new ArrayList<String>() {{   // beet
        add("Beacon 1");
    }});
    placesByBeacons.put("61045:1044", new ArrayList<String>() {{    // pink
        add("Beacon 2");
    }});
    PLACES_BY_BEACONS = Collections.unmodifiableMap(placesByBeacons);
}

private List<String> placesNearBeacon(Beacon beacon) {
    String beaconKey = String.format("%d:%d", beacon.getMajor(), beacon.getMinor());
    if (PLACES_BY_BEACONS.containsKey(beaconKey)) {
        return PLACES_BY_BEACONS.get(beaconKey);
    }
    return Collections.emptyList();
}

/* ----------------------------------------------------------------------------------------------
                                            oncreate
   ---------------------------------------------------------------------------------------------- */
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    state_textview = (TextView) findViewById(R.id.state);   // initialize textview
    final Button startButton = (Button) findViewById(R.id.start); // initialize button

    checkExternalMedia();   // check availability of sd card for reading and writing
    verifyStoragePermissions(this); // check if storage permission has been given

    /*
                                 ACTIVITY                                               */

    beaconManager = new BeaconManager(this);
    beaconManager.setRangingListener(new BeaconManager.RangingListener() {

        @Override
        public void onBeaconsDiscovered(Region region, List<Beacon> list) {
            if (!list.isEmpty()) {                             // upon discovery of beacons, do:

                // indentify beacons
                final Beacon beacon_0 = list.get(0);
                final Beacon beacon_1 = list.get(1); // THIS LINE, IT KEEPS CRASHING THE APP

Anyone with any idea why? ):

2

You’re trying to access a second element of a list which probably has only one element (:

3

Hi @heypiotr! Thanks for the reply, I really appreciate it! ^^

I’m confused as to why the app is not able to detect my second beacon… The Estimote app from playstore clearly shows 2 beacons being detected. I double checked the major/minor as well. Do you know if there are any reasons why this could be happening?

4

Can’t see calls to “startRanging” in the code snippet you’ve shared, can you show us that part? Maybe the answer is in there.