Flutter commands

Contents

• Create a flutter app
• Build and run
  • Clean
  • Get packages
  • Build the generated files
  • Run
    • Debug mode
    • Release mode
    • Profile mode
  • Hot reload
• Maintenance
  • Upgrade
  • Change channel

Create a flutter app

We can use the terminal in order to create a flutter app:

flutter create myApp
cd myApp

Or we can use IntelliJ/Android Studio with a File > New > Project... and select flutter, after having installed the flutter plugin.

Build and run

Clean

flutter clean

Get packages

flutter pub get

Build the generated files

Sometimes, we want to generate files, for instance, when we use JSON format, and we want to serialize and deserialize objects, but not specify every serialization by hand. There is no introspection in dart, so a library like GSON in Android cannot be used, so in order to have an automated process, we have to use file generation. The files generated have the extension .g.dart, and the filename corresponds to the original file name. We have to include the generated file using this import part 'filename.g.dart';
If we use the generation of files, we have to generate them before we can compile correctly the project, using this command:

flutter pub run build_runner build --delete-conflicting-outputs

Run

To check the list of devices:

flutter devices

We receive a list with this format:

SM T720    • 420094dac44f2600 • android-arm64  • Android 9 (API 28)
Chrome     • chrome           • web-javascript • Google Chrome 80.0.3987.163
Web Server • web-server       • web-javascript • Flutter Tools

The second column is the device ID.

Debug mode

In order to run on a specific device, we run this command:

flutter run -d <device-id>

Release mode

To run:

flutter run --release

To build:

flutter build <build-target>

Where build-target can be ios, apk, appbundle, web, macos.

Profile mode

Profile mode is for profiling the app for performance.

flutter run --profile

Hot reload

Whenever we run a flutter app on debug mode, we can make use of the hot reload feature. That means the launched application is changed to match the change in the code almost instantly.
It works only with debug mode: that is because there are two types of compilation for flutter, one ahead of time that is used for release mode, and the other for debug mode, which can be sent to the device much faster. Most modifications of code can be hot reloaded, but there are some limitations.

Maintenance

Upgrade

flutter upgrade

Change channel

In order to check which channel we are using:

flutter channel

We will see which channel is selected:

Flutter channels:
* master
  dev
  beta
  stable

Here, the star means that the selected channel is master. It corresponds to the git branch that we are in. The installation of flutter is synchronized with the Git repository, and changing flutter channel means changing the branch that we are in, so there can be different functions not available on a channel, but available on another.

To change the channel, we then type flutter channel <channel-name>, then we can do a flutter upgrade.