Geofences on Android with GoogleApiClient

Road trip! Summer is almost here, and for families the world over, that means hopping in the car and
heading to a favorite vacation spot. For long trips, the inevitable “Are we there yet?” questions will ring forth from the kids in the back seat.
Wouldn’t it be great to give them an easy means to know definitively one way or another? Geofences can do just that! And may in fact lead to more peace and tranquility for the whole family. :]
“What’s a geofence?” I here you ask – it’s nothing more than a virtual perimeter around a specified geographic location, which can be monitored and used to trigger events when its boundaries are crossed.
In this tutorial, you’ll build an Android app named “AWTY?” which uses GoogleApiClient, a component of Google Play Services, to add geofences. Your users will be able to enter a name, location, and size for a desired geofence. When entering the geofence, your users will get an Android notification of a geofence crossing.

Note: If you are new to Android development and have any questions about the starter project or using Android Studio, it may help to check out some of the tutorials on Android development found on this site.

Getting Started

Download the starter project for this tutorial. This project was created using Android Studio 1.2.
Fire up Android Studio, and choose either Open an existing Android Studio project or File\Open…, then navigate to and select the downloaded project folder. Once the project is open, you may need to select View\Tool Windows\Project to see the project files in the Project pane.
There are seven source code files in the starter project; take a moment to familiarize yourself with them:

• AddGeofenceFragment.java: a DialogFragment used to create a geofence.
• AllGeofencesActivity.java: an ActionBarActivity that displays a single fragment.
• AllGeofencesAdapter.java: a RecyclerView adapter that transforms geofences to instances of CardView.
• AllGeofencesFragment.java: a Fragment that displays geofences in a RecyclerView.
• AreWeThereIntentService.java: an IntentService that will send a notification to the user when they enter a geofence.
• Constants.java: a class to hold some static constants.
• NamedGeofence.java: a model class that will be used to serialize the geofences.

The view-related classes have ViewHolder inner classes containing the associated views. Each of the res subfolders has a number of other resource files that define colors, strings, dimensions, and styles; res/layout has files for each of the activity and fragment classes. Finally, the listitem_geofence.xml layout file defines the CardView that will be used to display geofences.
The following build settings have been specified in build.gradle, and you should make sure you have the corresponding Android SDK packages installed:

• minSdkVersion: 16
• compileSdkversion: 22
• targetSdkVersion: 22
• buildToolsVersion: 22.0.1

Finally, note the dependencies for the starter project defined in build.gradle; the app includes the CardView and RecyclerView classes from the Android Support Library along with two third-party libraries: Gson, for serializing objects to JSON, and FAB, a library used to display a floating action button.

Note: If you are unsure how to check which SDKs you have installed, or how to install an SDK, then please review the tutorials I linked to above.

Running the Starter Project

Time to run up your app to see how it looks in its current state. Testing geofences on a physical device is best, but if need be, you can run the app on the Android emulator. Doing so requires an emulator setup with Google Play Services installed.
To create a new emulator that will work with Google Play Services, choose Tools\Android\AVD Manager from the Android Studio menu. Next choose the Create Virtual Device… button in the lower left:

Select the Nexus 5, and choose Next:

On the next screen, choose an API Level of 22 as this is the latest version at time of writing. For the best emulator performance, use an ABI of x86 or x86_64 if you have HAXM installed. If you don’t have HAXM, choose armebi-v7a for the ABI. Also, to use geofences in the emulator you must choose a target with Google APIs to ensure that Google Play Services are available:

Note: For more information on using an emulator with HAXM, check out this Intel document on HAXM.

Once you’ve selected your system image, click Finish in the lower right:

To test your new emulator, go back to the AVD Manager and hit play on the emulator you just created:

Press Ctrl-R or click the run button in the Android Studio toolbar to ensure the starter app builds and runs successfully:

Now that you’ve successfully launched the starter project, you can begin building out the full app. Time to start tracking your users…no, not really. Promise you’ll never, ever do that! :]

Working with GoogleApiClient

With the December 2014 release of Google Play Services 6.5, geofences are now created using GoogleApiClient. The Location package is one of the dependencies listed in build.gradle:

dependencies { compile fileTree(dir: 'libs', include: ['*.jar']) compile 'com.android.support:appcompat-v7:22.0.0' compile 'com.android.support:cardview-v7:22.0.0' compile 'com.android.support:recyclerview-v7:22.0.0'   compile 'com.google.code.gson:gson:2.3' compile 'com.github.shell-software:fab:1.0.5'   compile 'com.google.android.gms:play-services-location:6.5.87' }

While there are versions of Google Play Services higher than 6.5.87, this is a version that most of your users’ devices should have.
If you’ve never installed Google Play Services, go to Tools\Android\SDK Manager to open the Android SDK Manager and install the requisite library:

Creating Geofence Objects

The NamedGeofence class stores geofence data in primitives, but you will also use it to create Geofence objects.
Add the following public method to the class:

public Geofence geofence() { id = UUID.randomUUID().toString(); return new Geofence.Builder() .setRequestId(id) .setTransitionTypes(Geofence.GEOFENCE_TRANSITION_ENTER) .setCircularRegion(latitude, longitude, radius) .setExpirationDuration(Geofence.NEVER_EXPIRE) .build(); }

The above method uses the Builder pattern to instantiate a new geofence object. You first create a unique id for the geofence and then build a geofence based on the values in NamedGeofence. The geofence type is specified as GEOFENCE_TRANSITION_ENTER, and the geofence is set to never expire.

Note: Beyond the basic properties of location (in terms of latitude and longitude) and size (usually given as a radius), geofences can have a fixed lifespan, or stay active with no expiration.
Geofences can be defined as entry, which triggers when the user enters the fence; exit, when the user leaves the fence; dwell, where the user stays inside the fence for a certain length of time period, or even a combination of these three.
In this tutorial, you’ll stick with creating entry geofences.

Now that you have a way to create Geofence objects, it’s time to create a companion controller class.

Creating GeofenceController

You’ll use a singleton class named GeofenceController to interact with the GoogleApiClient.
Right-click on the app package name in app/src/main/java, select New\Java Class, name the class GeofenceController and click OK:

Next, add the following code to the file you just created:

public class GeofenceController {   private final String TAG = GeofenceController.class.getName();   private Context context; private GoogleApiClient googleApiClient; private Gson gson; private SharedPreferences prefs;   private List<NamedGeofence> namedGeofences; public List<NamedGeofence> getNamedGeofences() { return namedGeofences; }   private List<NamedGeofence> namedGeofencesToRemove;   private Geofence geofenceToAdd; private NamedGeofence namedGeofenceToAdd; }

Here, you’ve added a String TAG property, a Context property that you’ll need to connect with GoogleApiClient, a GoogleApiClient property, as well as Gson and SharedPreferences properties that you’ll use to serialize geofences to disk.
You’ve also added List properties to store the current geofences in memory and maintain a list of geofences to remove. Finally, there are properties that will store Geofence and NamedGeofence objects to be added to the list.
Be sure to add any required imports by clicking on the red highlighted types and pressing Option-Return for each one.
Next, add the following code just below the property declarations:

private static GeofenceController INSTANCE;   public static GeofenceController getInstance() { if (INSTANCE == null) { INSTANCE = new GeofenceController(); } return INSTANCE; }

This adds a private static property to hold the singleton reference to the GeofenceController class, as well as a method to create and access the instance.
Now add the following initializer to your class:

public void init(Context context) { this.context = context.getApplicationContext();   gson = new Gson(); namedGeofences = new ArrayList<>(); namedGeofencesToRemove = new ArrayList<>(); prefs = this.context.getSharedPreferences(Constants.SharedPrefs.Geofences, Context.MODE_PRIVATE); }

Make sure to import the ArrayList class. This method simply initializes the context and some other properties of the controller.
Open AllGeofencesActivity and add the following call to the bottom of onCreate():

GeofenceController.getInstance().init(this);

This simply initializes GeofenceController when the app starts.
Now that you’ve added the controller, run your app to make sure all is well; your app won’t look any different, but rest assured GeofenceController is there in the background, waiting to do its job.

Adding Geofences

When the user taps Add in AddGeofenceFragment to create a new fence, you’ll kick off a chain of calls that result in GeofenceController connecting to GoogleApiClient to add the geofence.
Both the Add and Cancel buttons in AddGeofenceFragment have existing OnClickListeners, so you simply need to add the listener calls.
Open AddGeofenceFragment and add the following to the end of onClick for the Cancel click listener:

if (listener != null) { listener.onDialogNegativeClick(AddGeofenceFragment.this); }

This code calls the negative click callback on the listener if it exists.
Next, replace onClick() for the Add click listener with the following:

public void onClick(View view) { // 1. Check for valid data if (dataIsValid()) { // 2. Create a named geofence NamedGeofence geofence = new NamedGeofence(); geofence.name = getViewHolder().nameEditText.getText().toString(); geofence.latitude = Double.parseDouble( getViewHolder().latitudeEditText.getText().toString()); geofence.longitude = Double.parseDouble( getViewHolder().longitudeEditText.getText().toString()); geofence.radius = Float.parseFloat( getViewHolder().radiusEditText.getText().toString()) * 1000.0f;   // 3. Call listener and dismiss or show error if (listener != null) { listener.onDialogPositiveClick(AddGeofenceFragment.this, geofence); dialog.dismiss(); } } else { // 4. Display an error message showValidationErrorToast(); } }

You do the following things when the user taps the Add button:

1. Check if the user entered valid data.
2. If so, create a new NamedGeofence and set its properties.
3. Call the listener and dismiss the dialog.
4. If the user entered invalid data, show a validation error toast.

Connecting to GoogleApiClient

Add the following interface to the bottom of GeofenceController:

public interface GeofenceControllerListener { void onGeofencesUpdated(); void onError(); }

You’ll call the first interface method when you add or remove geofences, and the second if an error occurs.
Add the following field to the other fields near the top of the class:

private GeofenceControllerListener listener;

In order to add geofences to the device, GeofenceController must connect to GoogleApiClient and implement its defined interfaces ConnectionCallbacks and OnConnectionFailedListener.
Add the following code after the listener you added above:

private GoogleApiClient.ConnectionCallbacks connectionAddListener = new GoogleApiClient.ConnectionCallbacks() { @Override public void onConnected(Bundle bundle) {   }   @Override public void onConnectionSuspended(int i) {   } };   private GoogleApiClient.OnConnectionFailedListener connectionFailedListener = new GoogleApiClient.OnConnectionFailedListener() { @Override public void onConnectionFailed(ConnectionResult connectionResult) {   } };

This declares the add geofence and connection failed callbacks. Make sure to import the required headers for Bundle and ConnectionResult.
Before implementing the callbacks, add the following two helper methods to the bottom of the class:

private GeofencingRequest getAddGeofencingRequest() { List<Geofence> geofencesToAdd = new ArrayList<>(); geofencesToAdd.add(geofenceToAdd); GeofencingRequest.Builder builder = new GeofencingRequest.Builder(); builder.setInitialTrigger(GeofencingRequest.INITIAL_TRIGGER_ENTER); builder.addGeofences(geofencesToAdd); return builder.build(); }   private void connectWithCallbacks(GoogleApiClient.ConnectionCallbacks callbacks) { googleApiClient = new GoogleApiClient.Builder(context) .addApi(LocationServices.API) .addConnectionCallbacks(callbacks) .addOnConnectionFailedListener(connectionFailedListener) .build(); googleApiClient.connect(); }

getAddGeofencingRequest() adds the geofenceToAdd object to an ArrayList, then uses the builder pattern to create a GeofencingRequest object that will be used in the connection callbacks. connectWithCallbacks() populates the googleApiClient property and uses it to connect to the location service.
Make sure to import both GeofencingRequest and LocationServices.
Now add the following two helper methods:

private void sendError() { if (listener != null) { listener.onError(); } }   private void saveGeofence() { namedGeofences.add(namedGeofenceToAdd); if (listener != null) { listener.onGeofencesUpdated(); } }

sendError() calls the listener to pass along the error. saveGeofence() adds the new geofence to the controller’s list of geofences and calls the listener’s onGeofencesUpdated method.
With these two helper methods in place, add the following code to onConnected() within connectionAddListener:

// 1. Create an IntentService PendingIntent Intent intent = new Intent(context, AreWeThereIntentService.class); PendingIntent pendingIntent = PendingIntent.getService(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);   // 2. Associate the service PendingIntent with the geofence and call addGeofences PendingResult<Status> result = LocationServices.GeofencingApi.addGeofences( googleApiClient, getAddGeofencingRequest(), pendingIntent);   // 3. Implement PendingResult callback result.setResultCallback(new ResultCallback<Status>() {   @Override public void onResult(Status status) { if (status.isSuccess()) { // 4. If successful, save the geofence saveGeofence(); } else { // 5. If not successful, log and send an error Log.e(TAG, "Registering geofence failed: " + status.getStatusMessage() + " : " + status.getStatusCode()); sendError(); } } });

Here’s the play-by-play of the code above:

1. Create a PendingIntent for AreWeThereIntentService.
2. Associate the pending intent with geofenceToAdd and make the call to addGeofences().
3. Handle the PendingResult callback.
4. On success, make a call to save the geofence.
5. On error, make a call to send an error.

Add the red missing imports just like before. The imports for Status, ResultCallback, and LocationServices are all from subpackages of com.google.android.gms.
Add the following public method to GeofenceController you can use to start the process of adding a geofence:

public void addGeofence(NamedGeofence namedGeofence, GeofenceControllerListener listener) { this.namedGeofenceToAdd = namedGeofence; this.geofenceToAdd = namedGeofence.geofence(); this.listener = listener;   connectWithCallbacks(connectionAddListener); }

Here you simply hold the references to the geofence object and listener you’re going to create.

Wiring Everything Up

All the hooks are in place and ready to be connected. Open AllGeofencesFragment, and add the following along with the other properties:

private GeofenceController.GeofenceControllerListener geofenceControllerListener = new GeofenceController.GeofenceControllerListener() { @Override public void onGeofencesUpdated() { refresh(); }   @Override public void onError() { showErrorToast(); } };

The update callback refreshes the UI while the error callback displays a an error message.
You now need to hook up the adapter in order for the geofence card views to display.
Add the following near the end of onViewCreated(), just above the call to refresh():

allGeofencesAdapter = new AllGeofencesAdapter(GeofenceController.getInstance().getNamedGeofences()); viewHolder.geofenceRecyclerView.setAdapter(allGeofencesAdapter);

Here you instantiate allGeofencesAdapter with the list of named geofences and set the adapter on the recycler view.
Add the following code to refresh():

allGeofencesAdapter.notifyDataSetChanged();   if (allGeofencesAdapter.getItemCount() > 0) { getViewHolder().emptyState.setVisibility(View.INVISIBLE); } else { getViewHolder().emptyState.setVisibility(View.VISIBLE); }

Here you notify the adapter that data has been updated and show or hide the empty state based on whether or not there were any results.
Finally, add the following line to onDialogPositiveClick():

GeofenceController.getInstance().addGeofence(geofence, geofenceControllerListener);

When the user taps the Add button, the controller kicks off the add geofence chain.
It’s time to test this all out!
Build and run. Tap the floating action button, and enter some geofence data. If you need to find a specific location, Google Maps will give you the latitude and longitude you require. It’s best to use six significant figures after the decimal.
You should see your first geofence card:

If you’re developing on the emulator, you may receive an error when you attempt to add a geofence. If you do, follow these steps to add location permissions to your emulator:

1. Go to Settings\Location in your emulator.
2. Tap on Mode; on Lollipop this is near the top of the list.
3. Set the mode to set to Device Only, then set the mode to any other option, such as High accuracy.
4. Tap Agree on the “Use Google’s location service?” popup.

This should remove the error you received when adding geofences in the emulator.
Add a few of your favorite destinations as new geofences and scroll through the list:

Your users can add as many geofences as they like, but right now they’ll lose their data when the app restarts. Time to implement a save data function!

Adding Persistence

Open GeofenceController.java and add the following code to the bottom of saveGeofence():

String json = gson.toJson(namedGeofenceToAdd); SharedPreferences.Editor editor = prefs.edit(); editor.putString(namedGeofenceToAdd.id, json); editor.apply();

Here you use Gson to convert namedGeofenceToAdd into JSON and store that JSON as a string in the users’ shared preferences.
That will save the newly created geofence, but what about reloading saved geofences when the app launches?
Add the following method to GeofenceController:

private void loadGeofences() { // Loop over all geofence keys in prefs and add to namedGeofences Map<String, ?> keys = prefs.getAll(); for (Map.Entry<String, ?> entry : keys.entrySet()) { String jsonString = prefs.getString(entry.getKey(), null); NamedGeofence namedGeofence = gson.fromJson(jsonString, NamedGeofence.class); namedGeofences.add(namedGeofence); }   // Sort namedGeofences by name Collections.sort(namedGeofences); }

First, you create a map for all the geofence keys. You then loop over all the keys and use Gson to convert the saved JSON back into a NamedGeofence. Finally, you sort the geofences by name.
As always, import the missing headers; in this case, Map and Collections.
Add the following code to the end of init() to call your new method:

loadGeofences();

Build and run. Add a geofence or two, then use the app switcher to kill the app and run it again. You should see your geofences loaded back up from disk:

Removing Geofences

Adding geofences is handy, but what if you want to remove some – or all – of them?
Add the following callback to GeofenceController, which is similar to the one you wrote for adding fences:

private GoogleApiClient.ConnectionCallbacks connectionRemoveListener = new GoogleApiClient.ConnectionCallbacks() { @Override public void onConnected(Bundle bundle) { // 1. Create a list of geofences to remove List<String> removeIds = new ArrayList<>(); for (NamedGeofence namedGeofence : namedGeofencesToRemove) { removeIds.add(namedGeofence.id); }   if (removeIds.size() > 0) { // 2. Use GoogleApiClient and the GeofencingApi to remove the geofences PendingResult<Status> result = LocationServices.GeofencingApi.removeGeofences( googleApiClient, removeIds); result.setResultCallback(new ResultCallback<Status>() {   // 3. Handle the success or failure of the PendingResult @Override public void onResult(Status status) { if (status.isSuccess()) { removeSavedGeofences(); } else { Log.e(TAG, "Removing geofence failed: " + status.getStatusMessage()); sendError(); } } }); } }   @Override public void onConnectionSuspended(int i) { Log.e(TAG, "Connecting to GoogleApiClient suspended."); sendError(); } };

Here’s what the callback above does:

1. Builds a list of geofence id values to remove.
2. Removes the list of geofences you just built from the device.
3. Handles success or failure of the removal in a result callback.

Now add the following helper methods to the bottom of the same class:

public void removeGeofences(List<NamedGeofence> namedGeofencesToRemove, GeofenceControllerListener listener) { this.namedGeofencesToRemove = namedGeofencesToRemove; this.listener = listener;   connectWithCallbacks(connectionRemoveListener); }   public void removeAllGeofences(GeofenceControllerListener listener) { namedGeofencesToRemove = new ArrayList<>(); for (NamedGeofence namedGeofence : namedGeofences) { namedGeofencesToRemove.add(namedGeofence); } this.listener = listener;   connectWithCallbacks(connectionRemoveListener); }   private void removeSavedGeofences() { SharedPreferences.Editor editor = prefs.edit();   for (NamedGeofence namedGeofence : namedGeofencesToRemove) { int index = namedGeofences.indexOf(namedGeofence); editor.remove(namedGeofence.id); namedGeofences.remove(index); editor.apply(); }   if (listener != null) { listener.onGeofencesUpdated(); } }

The first two are public methods that remove either a list of geofences, or all geofences. The third method removes geofences from the users’ shared preferences and then alerts the listener that geofences have been updated.
To get this all working, you’ll need to wire up the DELETE button in the geofence card view.
Open AllGeofencesFragment.java and add the following to onViewCreated(), just before the call to refresh():

allGeofencesAdapter.setListener(new AllGeofencesAdapter.AllGeofencesAdapterListener() { @Override public void onDeleteTapped(NamedGeofence namedGeofence) { List<NamedGeofence> namedGeofences = new ArrayList<>(); namedGeofences.add(namedGeofence); GeofenceController.getInstance().removeGeofences(namedGeofences, geofenceControllerListener); } });

Here you add the geofence to be deleted to a list, then you pass that list to removeGeofences().
Build and run. Tap DELETE on any geofence, and you’ll be prompted to confirm the deletion:

Click YES and you’ll see the geofence disappear from the list.
Wouldn’t it be great if you could delete them all at once? That would be a perfect job for a menu item.
Open AllGeofencesActivity.java and add the following:

@Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.menu_all_geofences, menu);   MenuItem item = menu.findItem(R.id.action_delete_all);   if (GeofenceController.getInstance().getNamedGeofences().size() == 0) { item.setVisible(false); }   return true; }

This simply shows a delete menu item if there are existing geofences. Add the missing imports to remove any build errors.
Now go to AllGeofencesFragment, and add the following:

@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); }

The setHasOptionsMenu() call indicates that the fragment will handle the menu.
Next, add the following override to AllGeofencesFragment:

@Override public boolean onOptionsItemSelected(MenuItem item) { int id = item.getItemId(); if (id == R.id.action_delete_all) { AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); builder.setMessage(R.string.AreYouSure) .setPositiveButton(R.string.Yes, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { GeofenceController.getInstance().removeAllGeofences(geofenceControllerListener); } }) .setNegativeButton(R.string.No, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int id) { // User cancelled the dialog } }) .create() .show(); return true; }   return super.onOptionsItemSelected(item); }

This code builds an AlertDialog to confirm the user wants to delete all geofences, and if so, calls removeAllGeofences on GeofenceController. Import any missing headers as you’ve done previously.
Finally, add the following line to the bottom of refresh():

getActivity().invalidateOptionsMenu();

Invalidating the menu causes the menu to be removed if there are no geofences.
Build and run. Add multiple geofences, then bring up the menu and tap the Delete All Geofences option:

Poof! Your geofences are no more. :]

Displaying a Notification

There’s nothing yet to inform a user when they’ve reached one of their geofences. Time to fix that!
Open up AreWeThereIntentService.java; you’ll see the starter project includes an empty onHandleIntent() implementation. The pending intent you associated with the geofence triggers AreWeThereIntentService and fires the onHandleIntent() callback.
Add the following implementation to onHandleIntent(), importing the missing headers as you go:

prefs = getApplicationContext().getSharedPreferences( Constants.SharedPrefs.Geofences, Context.MODE_PRIVATE); gson = new Gson();   // 1. Get the event GeofencingEvent event = GeofencingEvent.fromIntent(intent); if (event != null) { if (event.hasError()) { onError(event.getErrorCode()); } else {   // 2. Get the transition type int transition = event.getGeofenceTransition(); if (transition == Geofence.GEOFENCE_TRANSITION_ENTER || transition == Geofence.GEOFENCE_TRANSITION_DWELL || transition == Geofence.GEOFENCE_TRANSITION_EXIT) { List<String> geofenceIds = new ArrayList<>();   // 3. Accumulate a list of event geofences for (Geofence geofence : event.getTriggeringGeofences()) { geofenceIds.add(geofence.getRequestId()); } if (transition == Geofence.GEOFENCE_TRANSITION_ENTER || transition == Geofence.GEOFENCE_TRANSITION_DWELL) { // 4. Pass the geofence list to the notification method onEnteredGeofences(geofenceIds); } } }   }

Once you set the values of the prefs and gson properties of the service, you do the following:

1. Create a GeofencingEvent object from the service intent.
2. Create an integer that stores the type of geofence transition.
3. Build up a list of ids that triggered the service.
4. Pass that list on to the notification method.

Add the following code to the beginning of onEnteredGeofences(), importing any missing headers:

// 1. Outer loop over all geofenceIds for (String geofenceId : geofenceIds) { String geofenceName = "";   // 2, Loop over all geofence keys in prefs and retrieve NamedGeofence from SharedPreferences Map<String, ?> keys = prefs.getAll(); for (Map.Entry<String, ?> entry : keys.entrySet()) { String jsonString = prefs.getString(entry.getKey(), null); NamedGeofence namedGeofence = gson.fromJson(jsonString, NamedGeofence.class); if (namedGeofence.id.equals(geofenceId)) { geofenceName = namedGeofence.name; break; } }   // 3. Set the notification text and send the notification String contextText = String.format(this.getResources().getString(R.string.Notification_Text), geofenceName); }

Here’s what happens when the device enters a geofence:

1. Loop over all the geofence ids.
2. Then loop again to pull out the geofence name from SharedPreferences.
3. Finally, you create a string to display to the user.

Now add the following to the end of the outer for loop, just below the creation of contextText:

// 1. Create a NotificationManager NotificationManager notificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);   // 2. Create a PendingIntent for AllGeofencesActivity Intent intent = new Intent(this, AllGeofencesActivity.class); intent.addFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_CLEAR_TOP); PendingIntent pendingNotificationIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);   // 3. Create and send a notification Notification notification = new NotificationCompat.Builder(this) .setSmallIcon(R.mipmap.ic_launcher) .setContentTitle(this.getResources().getString(R.string.Notification_Title)) .setContentText(contextText) .setContentIntent(pendingNotificationIntent) .setStyle(new NotificationCompat.BigTextStyle().bigText(contextText)) .setPriority(NotificationCompat.PRIORITY_HIGH) .setAutoCancel(true) .build(); notificationManager.notify(0, notification);

It looks dense, but it’s fairly straightforward code:

1. You create a notification manager using getSystemService().
2. Next, you create an intent to start up AllGeofencesActivity.
3. The builder pattern creates the notification with the intent using the app icon, a string constant title, and the context string.

Build and run. Nothing has changed visually, but all the plumbing is in place to show a notification to the user when they enter a geofence.
Time to take your app on a virtual road trip to test this all out! :]

Testing with Mock Locations

Ideally, you’d test this on a device and physically move into the geofences you created.
If you’re working with the emulator, or you don’t quite have the resources to fly to Bora Bora right now, there’s a way to mock your location and trigger your geofences in a virtual fashion. This tutorial focuses on mocking through the emulator, but you can also mock locations on a device using third-party apps such a Fake GPS and My Fake Location.

On the emulator, go to Settings\Developer options. Make sure Allow mock locations is already on:

Build and run the app in the emulator, and add some geofences.
In order to mock your location, you can use the Android Debug Bridge or telnet from the command line, but in this case you’ll use the Android DDMS which is bundled with Android Studio.
From the menu, choose Tools\Android\Android Device Monitor to open the DDMS window.
Choose the Emulator Control tab and locate (sorry!) Location Controls near the bottom:

Enter the longitude and latitude of one of your geofences for your mock location; note that the fields are reversed from your app’s interface. Click Send to mock the emulator location. You will likely need to open the Google Maps app on the emulator to trigger a location lookup.
If you don’t see anything pop up, click and drag the emulator screen down from where the battery is shown to display the notification center. At that point, you should see the geofence notification in the emulator:

Now you can say, with all certainty, “YES, we’re here!” :]

Where To Go From Here?

You can download the final project for this tutorial here.
You’ve come a long way in this tutorial: you’ve learned how to add and remove geofences, and trigger notifications for your user.
Geofences can be finicky on device reboot, as well as when Location services turn on and off. As a nice challenge for yourself, create a broadcast receiver that listens for BOOT_COMPLETED and reregisters your app’s stored geofences on reboot.
Also be sure to check out the Google Play Services overview on developer.android.com to find out what else you can do with Google Play Services and GoogleApiClient.
If you have any questions or comments on this tutorial, feel free to join the forum discussion below