Flutter Widgets

In Flutter, widgets are the basic building blocks used to construct user interfaces. Everything you see on the screen in a Flutter app, whether it’s a button, text field, image, or even the entire application itself, is represented by a widget. Widgets are used to define the structure, layout, and behavior of the UI elements within an app.

Widgets in Flutter are more than just visual components; they encapsulate both the UI and the behavior of an application’s elements. Each widget is an instance of a class that inherits from the Flutter framework’s Widget class. Widgets are lightweight and declarative, meaning they describe how the UI should look and behave rather than explicitly implementing rendering logic.

In the below PDF we discuss about Flutter Widgets  in detail in simple language, Hope this will help in better understanding.

Types of Flutter Widgets:

1. Stateless Widget:
A StatelessWidget is a widget that does not maintain any state internally. Once created, its properties remain immutable throughout the widget’s lifetime. This means that the appearance and behavior of a StatelessWidget cannot change after it is built. StatelessWidget instances are typically used to represent static UI elements that do not require updates based on user interaction or external data changes.

Characteristics of StatelessWidget:

  • Immutable Properties: The properties of a StatelessWidget are set once during initialization and cannot be modified thereafter.
  • No Internal State: StatelessWidget does not contain any internal state variables or data that can change over time.
  • Build Method: StatelessWidget overrides the build() method, which returns a Widget representing the UI subtree for this widget.
  • Efficient Rendering: Since StatelessWidget does not have to manage any state, Flutter can optimize rendering performance by caching and reusing instances of the widget.

Example of StatelessWidget:

import 'package:flutter/material.dart';


class MyButton extends StatelessWidget {
final String text;
final VoidCallback onPressed;

MyButton({required this.text, required this.onPressed});

Widget build(BuildContext context) {
return ElevatedButton(
onPressed: onPressed,
child: Text(text),

2. Stateful Widget:
A StatefulWidget is a widget that can maintain state internally. Unlike StatelessWidget, StatefulWidget instances can be updated over time in response to user interactions, animations, or changes in external data sources. StatefulWidget consists of two classes: one for the widget itself and another for its associated State object. The State object holds the mutable state data and manages updates to the widget’s appearance.

Characteristics of StatefulWidget:

  • Mutable State: StatefulWidget contains an associated State object that can hold mutable state data. Changes to this state trigger updates to the widget’s UI.
  • Stateful Widget Class: StatefulWidget is typically accompanied by a State class, which manages the widget’s state and implements the logic for handling updates.
  • setState Method: To update the widget’s state, StatefulWidget uses the setState() method, which triggers a rebuild of the widget’s UI subtree.
  • Dynamic UI: StatefulWidget is suitable for building interactive UI elements that require updates based on user input, data changes, or animations.

Example of StatefulWidget:

import 'package:flutter/material.dart';


class CounterWidget extends StatefulWidget {
_CounterWidgetState createState() => _CounterWidgetState();

class _CounterWidgetState extends State<CounterWidget> {
int _counter = 0;

void _incrementCounter() {
setState(() {

Widget build(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
‘Counter Value:’,
style: Theme.of(context).textTheme.headline4,
onPressed: _incrementCounter,
child: Text(‘Increment’),


In conclusion, Flutter widgets form the foundation of building visually appealing and interactive user interfaces for mobile apps. With its declarative approach to UI development, widget composition, hot reload feature, and support for custom widgets, Flutter offers a powerful toolkit for developers to unleash their creativity and deliver outstanding user experiences.

Related Question

Flutter widgets are the basic building blocks of a Flutter application’s user interface. They are elements that control layout, styling, and behavior, enabling developers to create interactive UIs.

Widgets in Flutter are classified into two main categories: StatelessWidget and StatefulWidget. StatelessWidget represents widgets whose state doesn’t change over time, while StatefulWidget represents widgets that can change dynamically.

Examples of StatelessWidget widgets include Text, Icon, Image, Container, and Row. These widgets represent static elements in the UI that don’t change based on user interaction or other factors.

StatefulWidget widgets are used for building UI elements that can change over time, such as buttons, text input fields, or progress indicators. They manage their own state, allowing developers to update the UI in response to user actions or external events.

Flutter uses a declarative approach to layout, where widgets describe their UI hierarchy in a tree structure. Widgets like Row, Column, and Container are used to arrange child widgets in various layouts, allowing for flexible and responsive UI designs.


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