title | description |
---|---|
Android Studio and IntelliJ |
How to develop Flutter apps in Android Studio or other IntelliJ products.
|
- Android Studio and IntelliJ
- Visual Studio Code
Follow the Set up an editor instructions to install the Dart and Flutter plugins.
Updates to the plugins are shipped on a regular basis. You should be prompted in the IDE when an update is available.
To check for updates manually:
- Open preferences (Android Studio > Check for Updates on macOS, Help > Check for Updates on Linux).
- If
dart
orflutter
are listed, update them.
You can create a new project in one of several ways.
Creating a new Flutter project from the Flutter starter app template differs between Android Studio and IntelliJ.
In Android Studio:
- In the IDE, click New Flutter Project from the Welcome window or File > New > New Flutter Project from the main IDE window.
- Specify the Flutter SDK path and click Next.
- Enter your desired Project name, Description, and Project location.
- If you might publish this app, set the company domain.
- Click Finish.
In IntelliJ:
- In the IDE, click New Project from the Welcome window or File > New > Project from the main IDE window.
- Select Flutter from the Generators list in the left panel
- Specify the Flutter SDK path and click Next.
- Enter your desired Project name, Description, and Project location.
- If you might publish this app, set the company domain.
- Click Finish.
When creating a new app, some Flutter IDE plugins ask for an
organization name in reverse domain order,
something like com.example
. Along with the name of the app,
this is used as the package name for Android, and the Bundle ID for iOS
when the app is released. If you think you might ever release this app,
it is better to specify these now. They cannot be changed once the app
is released. Your organization name should be unique.
To open an existing Flutter project:
-
In the IDE, click Open from the Welcome window, or File > Open from the main IDE window.
-
Browse to the directory holding your existing Flutter source code files.
-
Click Open.
:::important Do not use the New > Project from existing sources option for Flutter projects. :::
The Flutter plugin performs code analysis that enables the following:
- Syntax highlighting.
- Code completions based on rich type analysis.
- Navigating to type declarations (Navigate > Declaration), and finding type usages (Edit > Find > Find Usages).
- Viewing all current source code problems
(View > Tool Windows > Dart Analysis).
Any analysis issues are shown in the Dart Analysis pane:
{:width="90%"}
:::note You can debug your app in a few ways.
- Using DevTools, a suite of debugging and profiling tools that run in a browser and include the Flutter inspector.
- Using Android Studio's (or IntelliJ's) built-in debugging features, such as the ability to set breakpoints.
- Using the Flutter inspector, directly available in Android Studio and IntelliJ.
The instructions below describe features available in Android Studio and IntelliJ. For information on launching DevTools, see Running DevTools from Android Studio in the DevTools docs. :::
Running and debugging are controlled from the main toolbar:
When a Flutter project is open in the IDE, you should see a set of Flutter-specific buttons on the right-hand side of the toolbar.
:::note If the Run and Debug buttons are disabled, and no targets are listed, Flutter has not been able to discover any connected iOS or Android devices or simulators. You need to connect a device, or start a simulator, to proceed. :::
- Locate the Flutter Target Selector drop-down button. This shows a list of available targets.
- Select the target you want your app to be started on. When you connect devices, or start simulators, additional entries appear.
- Click the Play icon in the toolbar, or invoke Run > Run. The bottom Run pane shows logs output.
- If desired, set breakpoints in your source code.
- Click the Debug icon in the toolbar, or invoke Run > Debug.
- The bottom Debugger pane shows Stack Frames and Variables.
- The bottom Console pane shows detailed logs output.
- Debugging is based on a default launch configuration. To customize this, click the drop-down button to the right of the device selector, and select Edit configuration.
Flutter offers a best-in-class developer cycle enabling you to see the effect of your changes almost instantly with the Stateful Hot Reload feature. To learn more, check out Hot reload.
:::note To examine performance issues in Flutter, see the Timeline view. :::
To view the performance data, including the widget rebuild information, start the app in Debug mode, and then open the Performance tool window using View > Tool Windows > Flutter Performance.
To see the stats about which widgets are being rebuilt, and how often, click Show widget rebuild information in the Performance pane. The exact count of the rebuilds for this frame displays in the second column from the right. For a high number of rebuilds, a yellow spinning circle displays. The column to the far right shows how many times a widget was rebuilt since entering the current screen. For widgets that aren't rebuilt, a solid grey circle displays. Otherwise, a grey spinning circle displays.
:::secondary The app shown in this screenshot has been designed to deliver poor performance, and the rebuild profiler gives you a clue about what is happening in the frame that might cause poor performance. The widget rebuild profiler is not a diagnostic tool, by itself, about poor performance. :::
The purpose of this feature is to make you aware when widgets are rebuilding—you might not realize that this is happening when just looking at the code. If widgets are rebuilding that you didn't expect, it's probably a sign that you should refactor your code by splitting up large build methods into multiple widgets.
This tool can help you debug at least four common performance issues:
-
The whole screen (or large pieces of it) are built by a single StatefulWidget, causing unnecessary UI building. Split up the UI into smaller widgets with smaller
build()
functions. -
Offscreen widgets are being rebuilt. This can happen, for example, when a ListView is nested in a tall Column that extends offscreen. Or when the RepaintBoundary is not set for a list that extends offscreen, causing the whole list to be redrawn.
-
The
build()
function for an AnimatedBuilder draws a subtree that does not need to be animated, causing unnecessary rebuilds of static objects. -
An Opacity widget is placed unnecessarily high in the widget tree. Or, an Opacity animation is created by directly manipulating the opacity property of the Opacity widget, causing the widget itself and its subtree to rebuild.
You can click on a line in the table to navigate to the line in the source where the widget is created. As the code runs, the spinning icons also display in the code pane to help you visualize which rebuilds are happening.
Note that numerous rebuilds doesn't necessarily indicate a problem. Typically you should only worry about excessive rebuilds if you have already run the app in profile mode and verified that the performance is not what you want.
And remember, the widget rebuild information is only available in a debug build. Test the app's performance on a real device in a profile build, but debug performance issues in a debug build.
If you have additional tips we should share, let us know!
Assists are code changes related to a certain code identifier.
A number of these are available when the cursor is placed on a
Flutter widget identifier, as indicated by the yellow lightbulb icon.
The assist can be invoked by clicking the lightbulb, or by using the
keyboard shortcut (Alt
+Enter
on Linux and Windows,
Option
+Return
on macOS), as illustrated here:
Quick Fixes are similar, only they are shown with a piece of code has an error and they can assist in correcting it. They are indicated with a red lightbulb.
This can be used when you have a widget that you want to wrap in a surrounding
widget, for example if you want to wrap a widget in a Row
or Column
.
Similar to the assist above, but for wrapping an existing list of widgets rather than an individual widget.
Changes a child argument to a children argument, and wraps the argument value in a list.
Live templates can be used to speed up entering typical code structures. They are invoked by typing their prefix, and then selecting it in the code completion window:
The Flutter plugin includes the following templates:
- Prefix
stless
: Create a new subclass ofStatelessWidget
. - Prefix
stful
: Create a new subclass ofStatefulWidget
and its associated State subclass. - Prefix
stanim
: Create a new subclass ofStatefulWidget
and its associated State subclass, including a field initialized with anAnimationController
.
You can also define custom templates in Settings > Editor > Live Templates.
Hot reload
On Linux (keymap Default for XWin) and Windows the keyboard shortcuts
are Control
+Alt
+;
and Control
+Backslash
.
On macOS (keymap Mac OS X 10.5+ copy) the keyboard shortcuts are
Command
+Option
and Command
+Backslash
.
Keyboard mappings can be changed in the IDE Preferences/Settings: Select Keymap, then enter flutter into the search box in the upper right corner. Right click the binding you want to change and Add Keyboard Shortcut.
Hot reload works by injecting updated source code files into the running Dart VM (Virtual Machine). This includes not only adding new classes, but also adding methods and fields to existing classes, and changing existing functions. A few types of code changes cannot be hot reloaded though:
- Global variable initializers
- Static field initializers
- The
main()
method of the app
For these changes you can fully restart your application, without having to end your debugging session. To perform a hot restart, don't click the Stop button, simply re-click the Run button (if in a run session) or Debug button (if in a debug session), or shift-click the 'hot reload' button.
Opening the root directory of a Flutter project doesn't expose all the Android
files to the IDE. Flutter apps contain a subdirectory named android
. If you
open this subdirectory as its own separate project in Android Studio, the IDE
will be able to fully support editing and refactoring all Android files (like
Gradle scripts).
If you already have the entire project opened as a Flutter app in Android Studio, there are two equivalent ways to open the Android files on their own for editing in the IDE. Before trying this, make sure that you're on the latest version of Android Studio and the Flutter plugins.
- In the "project view", you should see a subdirectory immediately under
the root of your flutter app named
android
. Right click on it, then select Flutter > Open Android module in Android Studio. - OR, you can open any of the files under the
android
subdirectory for editing. You should then see a "Flutter commands" banner at the top of the editor with a link labeled Open for Editing in Android Studio. Click that link.
For both options, Android Studio gives you the option to use separate windows or to replace the existing window with the new project when opening a second project. Either option is fine.
If you don't already have the Flutter project opened in Android studio, you can open the Android files as their own project from the start:
- Click Open an existing Android Studio Project on the Welcome splash screen, or File > Open if Android Studio is already open.
- Open the
android
subdirectory immediately under the flutter app root. For example if the project is calledflutter_app
, openflutter_app/android
.
If you haven't run your Flutter app yet, you might see Android Studio report a
build error when you open the android
project. Run flutter pub get
in
the app's root directory and rebuild the project by selecting Build > Make
to fix it.
To enable editing of Android code in IntelliJ IDEA, you need to configure the location of the Android SDK:
- In Preferences > Plugins, enable Android Support if you haven't already.
- Right-click the android folder in the Project view, and select Open Module Settings.
- In the Sources tab, locate the Language level field, and select level 8 or later.
- In the Dependencies tab, locate the Module SDK field,
and select an Android SDK. If no SDK is listed, click New
and specify the location of the Android SDK.
Make sure to select an Android SDK matching the one used by
Flutter (as reported by
flutter doctor
). - Click OK.
Important known issues that might impact your experience are documented in the Flutter plugin README file.
All known bugs are tracked in the issue trackers:
- Flutter plugin: GitHub issue tracker
- Dart plugin: JetBrains YouTrack
We welcome feedback, both on bugs/issues and feature requests. Prior to filing new issues:
- Do a quick search in the issue trackers to see if the issue is already tracked.
- Make sure you have updated to the most recent version of the plugin.
When filing new issues, include the output of flutter doctor
.