Creating and Running a Wearable App

Wearable apps run directly on the wearable device, giving you access to low-level hardware such as sensors, activities, services, and more, right on the wearable.

A companion handheld app that contains the wearable app is also required when you want to publish to the Google Play store. Wearables don't support the Google Play store, so users download the companion handheld app, which automatically pushes the wearable app to the wearable. The handheld app is also useful for doing heavy processing, network actions, or other work and sending the results to the wearable.

This lesson goes over how to set up a device or emulator and create one project to contain both your wearable and handheld apps.

Update Your SDK

Before you begin building wearable apps, you must:

• Update your SDK tools to version 23.0.0 or higher
  The updated SDK tools enable you to build and test wearable apps.
• Update your SDK with Android 4.4W.2 (API 20) or higher
  The updated platform version provides new APIs for wearable apps.

To update your SDK with these components, see Get the latest SDK tools.

Set Up an Android Wear Emulator or Device

We recommend that you develop on real hardware so you can better gauge the user experience. However, the emulator lets you test out different types of screen shapes, which is useful for testing.

Set up an Android Wear Virtual Device

To set up an Android Wear virtual device:

1. Click Tools > Android > AVD Manager.
2. Click Create Virtual Device....
1. Click Wear in the Category list:
2. Select Android Wear Square or Android Wear Round.
3. Click Next.
4. Select a release name (for example, KitKat Wear).
5. Click Next.
6. (Optional) Change any preferences for your virtual device.
7. Click Finish.
3. Start the emulator:
   1. Select the virtual device you just created.
   2. Click the Play button.
   3. Wait until the emulator initializes and shows the Android Wear home screen.
4. Pair your handheld with the emulator:
   1. On your handheld, install the Android Wear app from Google Play.
   2. Connect the handheld to your machine through USB.
   3. Forward the AVD's communication port to the connected handheld device (you must do this every time the handheld is connected):

      adb -d forward tcp:5601 tcp:5601

   4. Start the Android Wear app on your handheld device and connect to the emulator.
   5. Tap the menu on the top right corner of the Android Wear app and select Demo Cards.
   6. The cards you select appear as notifications on the home screen of the emulator.

Set Up an Android Wear Device

To set up an Android Wear device:

1. Install the Android Wear app, available on Google Play, on your handheld.
2. Follow the app's instructions to pair your handheld with your wearable. This allows you to test out synced handheld notifications, if you're building them.
3. Leave the Android Wear app open on your phone.
4. Connect the wearable to your machine through USB, so you can install apps directly to it as you develop. A message appears on both the wearable and the Android Wear app prompting you to allow debugging.

Note: If you can not connect your wearable to your machine via USB, follow the directions on Debugging over Bluetooth.

5. On the Android Wear app, check Always allow from this computer and tap OK.

The Android tool window on Android Studio shows the system log from the wearable. The wearable should also be listed when you run the adb devices command.

Create a Project

To begin development, create an app project that contains wearable and handheld app modules. In Android Studio, click File > New Project and follow the Project Wizard instructions, as described in Creating a Project. As you follow the wizard, enter the following information:

1. In the Configure your Project window, enter a name for your app and a package name.
2. In the Form Factors window:
   • Select Phone and Tablet and select API 9: Android 2.3 (Gingerbread) under Minimum SDK.
   • Select Wear and select API 20: Android 4.4 (KitKat Wear) under Minimum SDK.
3. In the first Add an Activity window, add a blank activity for mobile.
4. In the second Add an Activity window, add a blank activity for Wear.

When the wizard completes, Android Studio creates a new project with two modules, mobile and wear. You now have a project for both your handheld and wearable apps that you can create activities, services, custom layouts, and much more in. On the handheld app, you do most of the heavy lifting, such as network communications, intensive processing, or tasks that require long amounts of user interaction. When these are done, you usually notify the wearable of the results through notifications or by syncing and sending data to the wearable.

Note: The wear module also contains a "Hello World" activity that uses a WatchViewStub that inflates a layout based on whether the device's screen is round or square. The WatchViewStub class is one of the UI widgets that's provided by the wearable support library.

Install the Wearable App

When developing, you install apps directly to the wearable like with handheld apps. Use either adb install or the Play button on Android Studio.

When you're ready to publish your app to users, you embed the wearable app inside of the handheld app. When users install the handheld app from Google Play, a connected wearable automatically receives the wearable app.

Note: The automatic installation of wearable apps does not work when you are signing apps with a debug key and only works with release keys. See Packaging Wearable Apps for complete information on how to properly package wearable apps.

Include the Correct Libraries

As part of the Project Wizard, the correct dependencies are imported for you in the appropriate module's build.gradle file. However, these dependencies are not required, so read the following descriptions to find out if you need them or not:

The Android v4 support library (or v13, which includes v4) contains the APIs to extend your existing notifications on handhelds to support wearables.

For notifications that appear only on the wearable (meaning, they are issued by an app that runs on the wearable), you can just use the standard framework APIs (API Level 20) on the wearable and remove the support library dependency in the mobile module of your project.

To sync and send data between wearables and handhelds with the Wearable Data Layer APIs, you need the latest version of Google Play services. If you're not using these APIs, remove the dependency from both modules.

This is an unofficial library that includes UI widgets designed for wearables. We encourage you to use them in your apps, because they exemplify best practices, but they can still change at any time. However, if the libraries are updated, your apps won't break since they are compiled into your app. To get new features from an updated library, you just need to statically link the new version and update your app accordingly. This library is only applicable if you create wearable apps.

In the next lessons, you'll learn how to create layouts designed for wearables as well as how to use the various voice actions that are supported by the platform.