Creating and Monitoring Geofences

With Lost you can create Geofences to monitor when a user enters or exits an area and get notifications when this occurs.

First create a Geofence object:

Geofence geofence = new Geofence.Builder()
        .setRequestId(requestId)
        .setCircularRegion(latitude, longitude, radius)
        .setExpirationDuration(NEVER_EXPIRE)
        .build();

Then create a GeofencingRequest from all relevant Geofences:

GeofencingRequest request = new GeofencingRequest.Builder()
        .addGeofence(geofence)
        .build();

After this is done, you can create a PendingIntent to fire when the user enters/exits the Geofence. Usually this will send an Intent to an IntentService:

Intent serviceIntent = new Intent(getApplicationContext(), GeofenceIntentService.class);
PendingIntent pendingIntent = PendingIntent.getService(this, 0, serviceIntent, 0);

Finally, invoke the GeofencingApi method to register for updates:

LocationServices.GeofencingApi.addGeofences(client, request, pendingIntent);

Your IntentService will continue to receive updates as the user enters/exits the relevant Geofences until you remove the PendingIntent.