Build and run your app

Android Studio sets up new projects to deploy to the Android Emulator or a connected device. Once your app is installed, you can use Apply Changes to deploy certain code and resource changes without deploying a new APK each time you run.

To build and run your app, follow these steps:

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

2. From the target device drop-down menu, select the device that you want to run your app on.

   

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

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 may result in unexpected behavior but are still runnable).

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 the following: whether to deploy your app from an APK, Android App Bundle, or custom artifact; the module to run; package to deploy; activity to start; target device; emulator settings; logcat options; and more.

If the default settings don't suit your project or module, you can customize the Run/Debug configuration, or even 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.

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, select Build > Select Build Variant in the menu 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 1. The Build Variants panel has two columns for projects that do not 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 field.

For projects with native/C++ code, the Build Variants panel has three columns: Module, Active Build Variant, and 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 does not impact what is deployed.

Figure 2. 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 will apply the change to all dependent rows.

By default, new projects are set up with two build variants: a debug and release variant. You need to build the release variant to prepare your app for public release.

To build other variations of your app, each with different features or device requirements, you can define additional build variants.

Build your project

The Run button builds and deploys your app to a device. However, to build your app to share or upload to Google Play, you'll need to use one of the options in the Build menu to compile parts or all of your project. Before you select any of the build options listed in table 1, make sure you first select the build variant you want to use.

Table 1. Build options in the Build menu.

Menu Item	Description
Make Module	Compiles all source files in the selected module that have been modified since the last build, and all modules the selected module depends on recursively. The compilation includes dependent source files and any associated build tasks. You can select the module to build by selecting either the module name or one of its files in the Project window.
Make Project	Makes all modules.
Clean Project	Deletes all intermediate/cached build files.
Rebuild Project	Runs Clean Project for the selected build variant and produces an APK.
Build Bundle(s) / APK(s) > Build APK(s)	Builds an APK of all modules in the current project for their selected variant. When the build completes, a confirmation notification appears, providing a link to the APK file and a link to analyze it in the APK Analyzer. If the build variant you've selected is a debug build type, then the APK is signed with a debug key and it's ready to install. If you've selected a release variant, then, by default, the APK is unsigned and you must manually sign the APK. Alternatively, you can select Build > Generate Signed Bundle / APK from the menu bar. Android Studio saves the APKs you build in project-name/module-name/build/outputs/apk/.
Build Bundle(s) / APK(s) > Build Bundle(s)	Builds an Android App Bundle of all modules in the current project for their selected variant. When the build completes, a confirmation notification appears, providing a link to the app bundle and a link to analyze it in the APK Analyzer. If the build variant you've selected is a debug build type, then the app bundle is signed with a debug key, and you can use bundletool to deploy your app from the app bundle to a connected device. If you've selected a release variant, then the app bundle is unsigned by default and you must manually sign it using jarsigner. Alternatively, you can select Build > Generate Signed Bundle / APK from the menu bar. Android Studio saves the APKs you build in project-name/module-name/build/outputs/bundle/.
Generate Signed Bundle / APK	Brings up a dialog with a wizard to set up a new signing configuration, and build either a signed app bundle or APK. You need to sign your app with a release key before you can upload it to the Play Console. For more information about app signing, see Sign your app.

Note: The Run button builds an APK with testOnly="true", which means the APK can only be installed via adb (which Android Studio uses). If you want a debuggable APK that people can install without adb, select your debug variant and click Build Bundle(s) / APK(s) > Build APK(s).

For details about the tasks that Gradle executes for each command, open the Build window as described in the next section. For more information about Gradle and the build process, see Configure Your Build.

Monitor the build process

You can view details about the build process by clicking View > Tool Windows > Build (or by clicking Build in the tool window bar). The window displays the tasks that Gradle executes in order to build your app, as shown in figure 3.

Figure 3. The Build output window in Android Studio

1. Build tab: Displays the tasks 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 4.

   Figure 4. Inspect the Build output window for error messages

2. Sync tab: Displays tasks that Gradle executes to sync with your project files. Similar to the Build tab, if you encounter a sync error, select elements in the tree to find more information about the error.
3. Restart: Performs the same action as selecting Build > Make Project by generating intermediate build files for all modules in your project.
4. Toggle view: Toggles between displaying task execution as a graphical tree and displaying more detailed text output from Gradle—this is the same output you see in the Gradle Console window on Android Studio 3.0 and earlier.

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 some 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 Mac OSX, 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.

Live Edit (experimental)

Live Edit is an experimental feature in the Android Studio Electric Eel canary releases that allows you to update composables in emulators and physical devices in real time. When you update a composable function, your changes are applied in your device or emulator as you make that change. This functionality minimizes context switches between writing and building your app, allowing you to focus on writing code longer without interruption.

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 Limitations.

This feature is not a replacement for building and running your application or 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--for example, adding new methods while the app is running.
3. After you make an unsupported change, Run your app to resume Live Editing.

Figure 5. 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 quickly 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, ensure that you have the latest canary version of Android Studio Electric Eel 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 popup. 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 6. Templates you can choose from. For Live Edit, choose Empty Compose Activity.

4. Enter the following, and then click Finish.

   • Name: HelloWorld
   • Package name: com.example.helloworld
   • Save location: Default.
   • Language: Kotlin
   • Minimum SDK: Default

   Figure 7. Example project settings.

Enable Live Edit

1. In the IDE, 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.

   Figure 8. Select the Live Edit option from the settings.

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

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

4. After you turn on Live Edit, you should see the Live Edit green checkmark on the top right of the editor.

   

   Figure 9. The green checkmark and Live Edit dropdown arrow appear after you turn on Live Edit.

Make and review changes

In the editor, change the existing Greeting method in MainActivity to the following. Your changes appear instantaneously, as shown in figure 10.

@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)
    )
}

Figure 10. Live Edit changes to the Greeting method above appear instantly.

Troubleshooting

If you don't see your edits in the preview pane, Android Studio might have failed to update your edits. Check if the Live Edit UI indicator shows a paused icon, which indicates a compilation error.

Figure 11. To see more information about the error and suggestions for how to resolve it, hover over Live Edit: ON in the UI.

Limitations

The following is a list of current limitations.

• 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 may incur some performance penalty. We recommend that you Run your app and use a clean Release build if you are evaluating its performance.
• You must perform a full Run in order 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.

Frequently asked questions

• What is the current status of Live Edit?
  • Live Edit is available in the Android Studio Electric Eel canary channel as an experimental feature. You can turn it on or off by navigating 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 (e.g. modifier updates, 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. Avoid using it for changes such as method signature updates, adding new methods, or class hierarchy changes, which it does not support. For more information, see Limitations.
• When should I use Compose Preview?
  • Use Composition 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 (e.g. dark mode, locales, font scale).

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 Ctrl+Alt+F10 (or Control+Shift+Command+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 have not 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 Ctrl+F10 (or Control+Command+R on macOS).

Run

Deploys all changes and restarts the app. Use this option when the changes that you have made cannot be applied using either of the Apply Changes options. To learn more about the types of changes that require an app restart, see Limitations of Apply Changes.

Enable Run fallback for Apply Changes

After you've clicked 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. However, 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 bar.
   • On macOS, select Android Studio > Preferences from the menu bar.

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

3. Select the checkboxes to enable automatic Run fallback for either of the Apply Changes actions.

4. Click OK.

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).

Type of change	Minimum platform version
Adding a method	Android 11

Limitations of Apply Changes

Apply Changes is designed to speed up the app deployment process. However, there are some limitations for when it can be used. If you encounter any issues while using Apply Changes, file a bug.

Code changes that require app restart

Some code and resource changes cannot 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 either Apply Code Changes or Apply Changes and Restart Activity and have to restart your app before you can see your changes.
• If a library or plugin makes changes to your app's resource files, you can't use Apply Code Changes , and you must use Apply Changes and Restart Activity to see your changes.

You can avoid these limitations by disabling all automatic updates for your debug build variants.

For example, 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. You can disable this behavior so that you can 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.