What is a widget?
- Flutter course
- Beginner
- Lesson 11/99
- 4 min
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');
}
}Practice Print the build signature
In main, print two lines with print: donus Widget and parametre BuildContext.
Starter code
void main() {
// iki satır yazdır:
// donus Widget
// parametre BuildContext
}Sample solution
void main() {
print('donus Widget');
print('parametre BuildContext');
}Expected output
donus Widget parametre BuildContext
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What property do widgets have?
- Run on the server
- Mutable at runtime
- Can only display text
- Immutable after creation Correct answer
Explanation: Widgets are immutable; after creation their content cannot change. For changes a new widget is produced.
2 build return type
@override
____ build(BuildContext context) {
return Text('Merhaba');
}@override
Widget build(BuildContext context) {
return Text('Merhaba');
}Explanation: The build method returns a value of type Widget.
3 Widget concepts
| Term | Meaning |
|---|---|
Widget |
Immutable building block |
immutable |
Does not change after creation |
build |
Method that produces the appearance |
StatelessWidget |
Class that implements build |