Build and run your app

To see how your app looks and behaves on a device, you need to build and run it. Android Studio sets up new projects so that you can deploy your app to a virtual or a physical device with just a few clicks.

This overview focuses on how to use Android Studio to build and run your app for testing and debugging. For information on how to use Android Studio to build your app so that it can be released to users, see Build your app for release to users. For more detailed information about managing and customizing your build with or without Android Studio, see Configure your build.

Basic build and run

To build and run your app, follow these steps:

1. In the toolbar, select your app from the run configurations menu.

2. In the target device menu, select the device that you want to run your app on.

   

   If you don't have any devices configured, you need to either create an Android Virtual Device to use the Android Emulator or connect a physical device.

3. Click Run .

Android Studio warns you if you attempt to launch your project to a device that has an error or a warning associated with it. Iconography and stylistic changes differentiate between errors (device selections that result in a broken configuration) and warnings (device selections that might result in unexpected behavior but are still runnable).

Monitor the build process

To view details about the build process, select View > Tool Windows > Build or click Build in the tool window bar. The Build tool window displays the tasks that Gradle executes to build your app, as shown in figure 1.

Figure 1. The Build tool window in Android Studio.

1. Sync tab: Displays tasks that Gradle executes to sync with your project files. Similar to the Build Output tab, if you encounter a sync error, select elements in the tree to get more information about the error.
2. Build Output tab: Displays the tasks that Gradle executes as a tree, where each node represents either a build phase or a group of task dependencies. If you receive build-time or compile-time errors, inspect the tree and select an element to read the error output, as shown in figure 2.

   

   Figure 2. Inspect the Build Output tab for error messages.

3. Build Analyzer tab: Provides build performance analysis information about your build. See Troubleshoot build performance with Build Analyzer for more information.
4. Restart: Performs the same action as selecting Build > Make Project, generating intermediate build files for all modules in your project.
5. Filters: Filters out warnings, tasks, or both that completed successfully. This can make it easier to find issues in the output.

If your build variants use product flavors, Gradle also invokes tasks to build those product flavors. To view the list of all available build tasks, click View > Tool Windows > Gradle or click Gradle in the tool window bar.

If an error occurs during the build process, Gradle may recommend command-line options to help you resolve the issue, such as --stacktrace or --debug. To use command-line options with your build process:

1. Open the Settings or Preferences dialog:
   • On Windows or Linux, select File > Settings from the menu bar.
   • On macOS, select Android Studio > Preferences from the menu bar.
2. Navigate to Build, Execution, Deployment > Compiler.
3. In the text field next to Command-line Options, enter your command-line options.
4. Click OK to save and exit.

Gradle applies these command-line options the next time you try building your app.

Advanced build and run features

The default way to build and run your app in Android Studio should be sufficient to test a simple app. However, you can use these build and run features for more advanced use cases:

• To deploy your app in debug mode, click Debug . Running your app in debug mode lets you set breakpoints in your code, examine variables and evaluate expressions at run-time, and run debugging tools. To learn more, see Debug your app.

• If you have a larger, more complex app, use Apply Changes instead of clicking Run . This saves time, because you avoid restarting your app every time you want to deploy a change. For more information about Apply Changes, see the Deploy incrementally with Apply Changes section.

• If you're using Jetpack Compose, Live Edit is an experimental feature that lets you update composables in real time without re-clicking Run . This lets you focus on writing UI code with minimal interruption. For more information, see the Live Edit (experimental) section.

• If you have an app with multiple build variants or versions, you can choose which build variant to deploy by using the Build Variants tool window. For more information about running a specific build variant, see the Change the build variant section.

• To fine-tune app installation, launch, and test options, you can change the run/debug configuration. For more information about creating custom run/debug configurations, see the Create run/debug configurations section.

• We recommend that you use Android Studio for your development needs, but you can also deploy your app to a virtual or physical device from the command line. For more information, see Build your app from the command line.

Deploy incrementally with Apply Changes

In Android Studio 3.5 and higher, Apply Changes lets you push code and resource changes to your running app without restarting your app—and, in some cases, without restarting the current activity. This flexibility helps you control how much of your app is restarted when you want to deploy and test small, incremental changes while preserving your device's current state.

Apply Changes uses capabilities in the Android JVMTI implementation that are supported on devices running Android 8.0 (API level 26) or higher. To learn more about how Apply Changes works, see Android Studio Project Marble: Apply Changes.

Requirements

Apply Changes actions are only available when you meet the following conditions:

• You build the APK of your app using a debug build variant.
• You deploy your app to a target device or emulator that runs Android 8.0 (API level 26) or higher.

Use Apply Changes

Use the following options when you want to deploy your changes to a compatible device:

Apply Changes and Restart Activity : Attempts to apply both your resource and code changes by restarting your activity but without restarting your app. Generally, you can use this option when you've modified code in the body of a method or modified an existing resource.

You can also perform this action by pressing Control+Alt+F10 (Control+Command+Shift+R on macOS).

Apply Code Changes : Attempts to apply only your code changes without restarting anything. Generally, you can use this option when you've modified code in the body of a method but you haven't modified any resources. If you've modified both code and resources, use Apply Changes and Restart Activity instead.

You can also perform this action by pressing Control+F10 (Control+Command+R on macOS).

Run : Deploys all changes and restarts the app. Use this option when the changes you've made can't be applied using either of the Apply Changes options. To learn more about the types of changes that require an app restart, see the Limitations of Apply Changes section.

Enable run fallback for Apply Changes

When you click either Apply Changes and Restart Activity or Apply Code Changes, Android Studio builds a new APK and determines whether the changes can be applied. If the changes can't be applied and would cause Apply Changes to fail, Android Studio prompts you to Run your app again instead.

If you don't want to be prompted every time this occurs, you can configure Android Studio to automatically rerun your app when changes can't be applied. To enable this behavior, follow these steps:

1. Open the Settings or Preferences dialog:

   • On Windows or Linux, select File > Settings from the menu.
   • On macOS, select Android Studio > Preferences from the menu.

2. Navigate to Build, Execution, Deployment > Deployment.

3. Select the checkboxes to enable automatic run fallback for either or both of the Apply Changes actions.

4. Click OK.

Note: Some types of changes don't cause Apply Changes to fail but still require you to restart your app manually before you can see those changes. For example, if you make changes to an activity's onCreate() method, those changes only take effect after the activity is relaunched, so you must restart your app to see those changes.

Platform-dependent changes

Some features of Apply Changes depend on specific versions of the Android platform. To apply these kinds of changes, your app must be deployed to a device running that version of Android (or higher). For example, adding a method requires Android 11 or higher.

Limitations of Apply Changes

Apply Changes is designed to speed up the app deployment process. However, there are some limitations on when it can be used.

Code changes that require app restart

Some code and resource changes can't be applied until the app is restarted, including the following:

• Adding or removing a field
• Removing a method
• Changing method signatures
• Changing modifiers of methods or classes
• Changing class inheritance
• Changing values in enums
• Adding or removing a resource
• Changing the app manifest
• Changing native libraries (SO files)

Libraries and plugins

Some libraries and plugins automatically make changes to your app's manifest files or to resources that are referenced in the manifest. These automatic updates can interfere with Apply Changes in the following ways:

• If a library or plugin makes changes to your app's manifest, you can't use Apply Changes. You must restart your app to see your changes.
• If a library or plugin makes changes to your app's resource files, you can't use Apply Code Changes . You must use Apply Changes and Restart Activity (or restart your app) to see your changes.

To avoid these limitations, disable all automatic updates for your debug build variants.

For example, Firebase Crashlytics updates app resources with a unique build ID during every build, which prevents you from using Apply Code Changes and requires you to restart your app's activity to see your changes. Disable this behavior to use Apply Code Changes alongside Crashlytics with your debug builds.

Code that directly references content in an installed APK

If your code directly references content from your app's APK that's installed on the device, that code can cause crashes or misbehave after clicking Apply Code Changes . This behavior occurs because when you click Apply Code Changes the underlying APK on the device is replaced during installation. In these cases, you can click Apply Changes and Restart Activity or Run instead.

If you encounter any other issues while using Apply Changes, file a bug.

Live Edit (experimental)

Important: This is an experimental feature in active development, so you might experience some unstable behavior. It requires Jetpack Compose 1.3.0 or higher. Google is continuously working to improve this feature and welcomes your feedback. If you find an issue, please report it . Include information from Logcat and a description of the code change you were making.

Live Edit is an experimental feature in the Android Studio Giraffe canary releases that lets you update composables in emulators and physical devices in real time. This functionality minimizes context switches between writing and building your app, letting you focus on writing code longer without interruption.

Live Edit has two modes:

• Manual: Code changes are applied when they are manually saved using Control+S (Command+S for macOS).
• Automatic. Changes are applied in your device or emulator when you update a composable function.

Live Edit is focused on UI- and UX-related code changes. Live Edit doesn't support changes such as method signature updates, adding new methods, or class hierarchy changes. For more information, see the list of Limitations of Live Edit.

This feature is not a replacement for building and running your app or for Apply Changes. Instead, it's designed to optimize your workflow as you build, deploy, and iterate to develop Compose UI.

The best practice workflow is as follows:

1. Set up your application so that it can be run.
2. Live Edit as much as possible until you need to make a change that Live Edit doesn't support, such as adding new methods while the app is running.
3. After you make an unsupported change, click Run to restart your app and resume Live Edit.

Figure 3. In automatic mode, each time you make an edit that is supported by Live Edit the running app on your device or emulator is updated in real time.

Get started with Live Edit

To get started, follow these steps to create an empty Compose Activity, enable Live Edit for your project, and make changes with Live Edit.

Set up your new project

1. Before you begin, make sure that you have the latest canary version of Android Studio Giraffe installed and that the API level of your physical device or emulator is at least 30.

2. Open Android Studio and select New Project in the Welcome to Android Studio dialog. If you already have a project open, you can create a new one by navigating to File > New > New Project.

3. Choose the Empty Compose Activity template for Phone and Tablet, and then click Next.

   Figure 4. Templates you can choose from. For Live Edit, choose Empty Compose Activity.

4. Complete the New Project dialog with the required information: name, package name, save location, language (set to Kotlin), and minimum SDK.

   Figure 5. Example project settings.

5. Click Finish.

Enable Live Edit

1. Navigate to the settings to enable Live Edit.

   • On Windows or Linux, navigate to File > Settings > Editor > Live Edit.
   • On macOS, navigate to Android Studio > Preferences > Editor > Live Edit.

2. Select the Live Edit option and the mode you want to run from the settings.

   In manual mode, your code changes are applied every time you manually save, using Control+S (Command+S on macOS). In automatic mode, your code changes are applied in your device or emulator as you make your changes.

   Figure 6. The Live Edit settings.

3. In the editor, open the MainActivity file, which is the entry point for your app.

4. Click Run to deploy your app, and then click Split on the top right of the editor to open the preview.

5. After you turn on Live Edit, the Live Edit green checkmark appears in the top right of the editor:

   

Make and review changes

As you make supported changes in the editor, the preview updates automatically.

For example, edit the existing Greeting method in MainActivity to the following:

@Composable
fun Greeting(name: String) {
    Text(text = "Hello $name!",
        Modifier.padding(80.dp) // Outer padding; outside background
            .background(color = Color.Cyan) // Solid element background color
            .padding(16.dp) // Inner padding; inside background, around text)
    )
}

Your changes appear instantaneously in the preview, as shown in figure 7.

Figure 7. Preview displaying Live Edit changes to the Greeting method.

Troubleshoot Live Edit

If you don't see your edits in the preview pane, Android Studio might have failed to update your edits. Check whether the Live Edit UI indicator displays a paused icon, as shown in figure 8, which indicates a compilation error. For information about the error and suggestions for how to resolve it, click the error indicator.

Figure 8. Live Edit status indicator.

Limitations of Live Edit

Note: Live Edit is an experimental feature in Android Studio Giraffe canary builds, which means there are some known issues and limitations. Please send your feedback while Google is improving the feature. You can also see a list of open issues here.

The following is a list of current limitations.

• Live Edit requires Compose 1.3.0 or higher. If your project uses a lower version of Compose, Live Edit is disabled.
• Live Edit requires a physical device or emulator that is running API level 30 or higher.
• Live Edit only supports editing a function body, which means that you can't change the function name or the signature, add or remove a function, or change non-function fields.
• Live Edit-modified classes might incur some performance penalty. Run your app and use a clean release build if you are evaluating its performance.
• You must perform a full run for the debugger to operate on classes that you have modified with Live Edit.
• A running app might crash when you edit it with Live Edit. If this happens, you can redeploy the app with the Run button.
• Live Edit doesn't perform any bytecode manipulation that's defined in your project's build file—for example, bytecode manipulation that would be applied when the project is built using the options in the Build menu or by clicking the Build or Run buttons.
• Non-Composable functions are updated live on the device or emulator, and a full recomposition is triggered. The full recomposition might not invoke the updated function. For non-composable functions, you must trigger the newly updated functions or run the app again.
• Live Edit doesn't resume on app restarts. You must run the app again.
• Live Edit only supports debuggable processes.
• Live Edit does not support projects that use custom values for moduleName under kotlinOptions in build configuration.
• Live Edit doesn't work with multi-deploy deployments. This means that you can't deploy to one device, and then to another. Live Edit is only active on the last set of devices the app was deployed to.
• Live Edit works with multi-device deployments (deployments to multiple devices that were created through Select multiple devices in the target device dropdown). However, it's not officially supported and there might be issues. If you experience issues, please report them.

Frequently asked questions about Live Edit

• What is the current status of Live Edit?
  • Live Edit is available in the Android Studio Giraffe canary channel as an experimental feature. To turn it on or off, navigate to File > Settings > Editor > Live Edit (Android Studio > Preferences > Editor > Live Edit on macOS).
• When should I use Live Edit?
  • Use Live Edit when you want to quickly see the effect of updates to UX elements (such as modifier updates and animations) on the overall app experience.
• When should I avoid using Live Edit?
  • Live Edit is currently focused on UI- and UX-related code changes. It doesn't support changes such as method signature updates, adding new methods, or class hierarchy changes. For more information, see Limitations of Live Edit.
• When should I use Compose Preview?
  • Use Compose Preview when you're developing individual composables. Preview visualizes Compose elements and automatically refreshes to display the effect of code changes. Preview also supports viewing UI elements under different configurations and states, such as dark mode, locales, and font scale.

Change the build variant

By default, Android Studio builds the debug version of your app, which is intended for use only during development, when you click Run .

To change the build variant Android Studio uses, do one of the following:

• Select Build > Select Build Variant in the menu.
• Select View > Tool Windows > Build Variants in the menu.
• Click the Build Variants tab on the tool window bar.

For projects without native/C++ code, the Build Variants panel has two columns: Module and Active Build Variant. The Active Build Variant value for the module determines which build variant the IDE deploys to your connected device and is visible in the editor.

Figure 9. The Build Variants panel has two columns for projects that don't have native/C++ code.

To switch between variants, click the Active Build Variant cell for a module and choose the desired variant from the list.

For projects with native/C++ code, the Build Variants panel has three columns:

• Module
• Active Build Variant
• Active ABI

The Active Build Variant value for the module determines the build variant that the IDE deploys to your device and is visible in the editor. For native modules, the Active ABI value determines the ABI that the editor uses, but doesn't impact what is deployed.

Figure 10. The Build Variants panel adds the Active ABI column for projects with native/C++ code.

To change the build variant or ABI, click the cell for the Active Build Variant or Active ABI column and choose the desired variant or ABI from the list. After you change the selection, the IDE syncs your project automatically. Changing either column for an app or library module applies the change to all dependent rows.

By default, new projects are set up with two build variants: a debug variant and release variant. You need to build the release variant to prepare your app for public release. To define other variations of your app with different features or device requirements, you can define additional build variants.

Conflicts in Android Studio Build Variants dialog

In the Android Studio Build Variants dialog, you might see error messages indicating conflicts between build variants, such as the following:

This error doesn't indicate a build issue with Gradle. It indicates that the Android Studio IDE can't resolve symbols between the variants of the selected modules.

For example, if you have a module M1 that depends on variant v1 of module M2, but M2 has variant v2 selected in the IDE, you have unresolved symbols in the IDE. Suppose M1 depends on a class that is only available in v1; when v2 is selected, that class is not known by the IDE. Therefore it fails to resolve the class name and shows errors in the M1 module's code.

These error messages appear because the IDE can't load code for multiple variants simultaneously. In terms of your app’s build, however, the variant selected in this dialog has no effect, because Gradle builds your app with the source code specified in your Gradle build recipes, not based on what’s currently loaded in the IDE.

Change the run/debug configuration

When you run your app for the first time, Android Studio uses a default run configuration. The run configuration specifies whether to deploy your app from an APK or an Android App Bundle as well as the module to run, package to deploy, activity to start, target device, emulator settings, Logcat options, and more.

The default run/debug configuration builds an APK, launches the default project activity, and uses the Select Deployment Target dialog for target device selection. If the default settings don't suit your project or module, you can customize the run/debug configuration or create a new one at the project, default, and module levels.

To edit a run/debug configuration, select Run > Edit Configurations. For more information, see Create and edit run/debug configurations.