{"id":123,"date":"2025-07-30T19:39:58","date_gmt":"2025-07-31T00:39:58","guid":{"rendered":"https:\/\/blog.alangaelrojas.com\/?p=123"},"modified":"2025-07-30T19:39:58","modified_gmt":"2025-07-31T00:39:58","slug":"developing-a-wear-os-app","status":"publish","type":"post","link":"https:\/\/blog.alangaelrojas.com\/index.php\/2025\/07\/30\/developing-a-wear-os-app\/","title":{"rendered":"Developing a Wear OS app"},"content":{"rendered":"\n

Continuing with the topic of Wear OS development, in a previous article, we discussed the fundamentals of Wear OS development. If you haven’t seen it, I suggest you check that article<\/a> out and then come back here.<\/p>\n\n\n\n

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\ud83d\udcf2 Building a Connected Wear OS App: Overview<\/h3>\n\n\n\n

In this blog, we explore how to build a Wear OS app that communicates effectively with its companion Android app. Seamless communication is key to keeping both apps in sync, and Android provides us with three main tools to achieve this\u2014such as DataClient<\/code>, MessageClient<\/code>, and CapabilityClient<\/code>.<\/p>\n\n\n\n

We cover the two main ways of receiving data with DataClient<\/code>:<\/p>\n\n\n\n

    \n
  1. Using WearableListenerService<\/code><\/strong>: This allows you to listen for messages globally, even if the app is closed. By overriding methods like onMessageReceived()<\/code> and registering the service in the AndroidManifest.xml<\/code>, your app can handle incoming messages automatically.<\/li>\n\n\n\n
  2. Adding Listeners Locally<\/strong>: Alternatively, you can set up listeners directly in classes like Activity<\/code>, Fragment<\/code>, Service<\/code>, or ViewModel<\/code>, giving you more scoped and flexible control over communication.<\/li>\n<\/ol>\n\n\n\n

    We demonstrate this with an example in the RunningViewModel<\/code>, where we listen for both onDataChanged()<\/code> and onMessageReceived()<\/code> events, keeping the app reactive and synchronized.<\/p>\n\n\n\n

    To send messages from the Wear app to the phone, we use the MessageClient<\/code> and its sendMessage()<\/code> method, which takes three parameters: the node ID, a path (like \"\/start_stop\"<\/code>), and the message data. For example, sending the \"\/start_stop\"<\/code> command triggers the simulator to start or stop tracking data.<\/p>\n\n\n\n

    We also introduce the RunningActivity.kt<\/code>, which features a HorizontalPager<\/code> UI to provide a smooth, scrollable interface for navigating between views.<\/p>\n\n\n\n

    By combining all these tools, we demonstrate how to build a simple but fully connected Wear OS app that syncs effectively with its Android phone counterpart.<\/p>\n\n\n\n

    \n\n\n\n

    Project structure<\/h2>\n\n\n\n

    To start developing Wear, the initial setup in Android Studio doesn’t change much. In the New Project > Wear OS section, we can find these main options [Wear App + Tile or Empty Wear App].<\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    By selecting one of these two options, we will have the initial configurations of the application or the project itself. This step is crucial, depending on whether our app will work standalone or in conjunction with the companion and wear app. We also explained this in the previous article.<\/p>\n\n\n\n

    \u26a0\ufe0f For standalone mode, we will not have any limitation for the package name, we will have total freedom to choose any package name, however if our app will work in companion + wear app mode, the package name of our wear app must match the package name of our android app, this is important because later we will see how the internal communication between wear app and companion app is.<\/p>\n\n\n\n

    standalone<\/strong><\/td>companion + wear app<\/strong><\/td><\/tr>
    Does not matter<\/td>package name<\/strong> for both projects “com.wizeline.myapp”<\/td><\/tr>
    \"\"<\/td>\"\"<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    \"\"<\/p>\n\n\n\n

    Having said that, we can click on “Finish” and our IDE will open as if it were an Android project.<\/p>\n\n\n\n

    \ud83d\udc68\u200d\ud83d\udcbb Start developing<\/h2>\n\n\n\n

    Once the project is properly configured, we’ll have an empty activity with the traditional Android Studio composable Greeting <\/strong>template.
    We’ll notice that our class inherits\/extends ComponentActivity, which tells us our app is ready for Jetpack Compose, the declarative UI supported by androidx.wear.compose.<\/strong><\/p>\n\n\n\n

    \"\"
    A composable for a Fitness app example that shows a list of items<\/figcaption><\/figure>\n\n\n\n
    \"\"<\/figure>\n\n\n\n

    \ud83d\udce1 Communication with the companion app<\/h2>\n\n\n\n

    A fundamental part of building our app, along with the phone app, is enabling good communication between these two components, allowing us to keep their states in sync. For this, Android provides us with three main agents:<\/p>\n\n\n\n