What is meant by states in Flutter?

· 5 min read
What is meant by states in Flutter?
What is meant by states in Flutter?

As a beginner in Flutter, you may face some issues in understanding a state in Flutter. You may encounter other problems such as whether to use stateful or stateless widgets? So, in this article, we will see what is meant by states in Flutter.

What is meant by states in Flutter?

Flutter is declarative in nature. It means that Flutter builds its user interface to reflect the current state of the application. The state can be described as “whatever data you need to rebuild your user interface at any time”.

When the state of your application changes (for example, the user changes a switch on the configuration screen), you change the state and activate a new UI drawing. No changes are needed to the UI itself. It changes the state and then the UI is rebuilt from scratch. The states are defined in Flutter in two different ways:

  1. Stateless widget: In this, the build function is called only once. And it presents the user interface of the screen. This means that you will not be able to change the user interface again through the widget. It will immediately build the user interface.
    So, for those widgets, you will need to submit information before creating the widget.
  2. Stateful widgets: Widgets whose state can be changed after construction are called stateful widgets. The state of the application can be changed multiple times through different variables, inputs, and data sets. You can change the user interface of this widget with the help of the setState method without having to recompile it.

The state that you manage yourself can be separated into two types: Ephemeral state and App state. Below we have defined both the states in detail.

Ephemeral state:

This state is also known as UI state or local state. You can neatly contain this state in a single widget. Developers won’t need to use state management techniques such as ScopedModel, Redux, Provider, etc. However, you will need a stateful widget. You will only need setState to alter the current state. Below, you can see how the currently selected item in a bottom navigation bar is held in the _index field of the _MyHomepageState class. In this, _index is the ephemeral state.

class MyHomepage extends StatefulWidget {
    const MyHomepage({Key? key}) : super(key: key);

    @override
    _MyHomepageState createState() => _MyHomepageState();
    }

    class _MyHomepageState extends State<MyHomepage> {
    int _index = 0;

    @override
    Widget build(BuildContext context) {
        return BottomNavigationBar(
        currentIndex: _index,
        onTap: (newIndex) {
            setState(() {
            _index = newIndex;
            });
        },
        // ... items ...
        );
    }
    }

Here, it is completely natural to use setState () with a field in the State class of StatefulWidget. No other part of your app needs to access _index. Also, if the user closes and restarts the app, they won’t mind resetting _index to zero.

App State:

The state that you want to share in many parts of the application is known as the Application state. You can also maintain this state between many users. Examples of application state are:

  • User preferences.
  • Login info.
  • Notifications in a social networking app.
  • The shopping cart in an e-commerce app.
  • Read/unread the state of articles in a news app.

To manage the app state, you’ll need to research your options. Your choice depends on the complexity and nature of your app. It will also depend on your team’s experience and many other parameters.

Conclusion:

Thanks for remaining with us till the end of the article. So, in this article, we have seen what is meant by states in Flutter. We hope you have enjoyed reading this article. Also, feel free to comment with your suggestions and feedback.

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