What is a widget?

Learn that a widget is the core building block of Flutter.

What is a widget?

A widget is Flutter's fundamental building block. Everything on screen — text, button, padding — is a widget. Widgets are immutable: they do not change after creation. Each widget has a build method that produces its appearance.

Text('Merhaba')
Padding(
  padding: EdgeInsets.all(8.0),
  child: Text('Dolu'),
)

The build method

Every widget's build method describes how it appears on screen. build takes a BuildContext and returns a Widget. When the widget changes, build is called again and returns a new widget tree.

class Selam extends StatelessWidget {
  const Selam({super.key});

  @override
  Widget build(BuildContext context) {
    return Text('Merhaba');
  }
}

Exercise Print the build signature

In main, print two lines with print: donus Widget and parametre BuildContext.

Show example solution

void main() {
  print('donus Widget');
  print('parametre BuildContext');
}

Test yourself

What property do widgets have?
- Run on the server
- Mutable at runtime
- Can only display text
- Immutable after creation
Show answer

Immutable after creation — Widgets are immutable; after creation their content cannot change. For changes a new widget is produced.

build return type

@override
____ build(BuildContext context) {
  return Text('Merhaba');
}

Show answer

@override
Widget build(BuildContext context) {
  return Text('Merhaba');
}

Widget concepts

Widget

Immutable building block
immutable

Does not change after creation
build

Method that produces the appearance
StatelessWidget

Class that implements build

Next lesson: Widget tree

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies