Summary - Widget basics
- Flutter course
- Beginner
- Lesson 15/99
- 4 min
Combine widget, tree and BuildContext to build a simple UI.
Widget basics summary
The Flutter UI is a tree of immutable widgets. Each widget's build method produces its appearance and uses BuildContext to reach ancestral data in the tree. You start with a Material or Cupertino root widget and nest childs to build the UI.
MaterialApp(
home: Scaffold(
body: Center(
child: Builder(
builder: (context) => Text(
'Merhaba',
style: Theme.of(context).textTheme.bodyLarge,
),
),
),
),
)Practice Build the tree and run
In main, first print a message with print('agac kurulu'). Then call runApp with a MaterialApp whose home contains a Center wrapping Text('Hazir').
Starter code
import 'package:flutter/material.dart';
void main() {
// 'agac kurulu' mesajını print ile yazdır
// runApp ile bir MaterialApp çağır; home içinde Center ve Text kullan
}Sample solution
import 'package:flutter/material.dart';
void main() {
print('agac kurulu');
runApp(MaterialApp(home: Center(child: Text('Hazir'))));
}Expected output
agac kurulu
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What is the parameter of the build method?
- Color
- String
- int
- BuildContext Correct answer
Explanation: The build method signature is Widget build(BuildContext context).
2 Complete the build parameter
Question
Widget build(BuildContext ____) {
return Text('Hazir');
}
Answer
Widget build(BuildContext context) {
return Text('Hazir');
}Explanation: The parameter passed to the build method is conventionally named context.
3 Widget basics combined
| Term | Meaning |
|---|---|
build imzası |
Widget build(BuildContext context) |
Ağaç yürüyüşü |
How Flutter produces pixels |
Tema erişimi |
Via Theme.of(context) |
Görsel dil seçimi |
Material or Cupertino |