Flutter - Dart 문법 1

# New Flutter Project 하면 아래와 같이 기본 코드가 자동 생성된다.

import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
   # material 패키지를 연결시켜서 Dart 문법의 사용하는 기본 함수들이 이용한다.

 

class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
   # 데이터의 변화가 없고 고정적으로 사용되는 Widget
   # 단 한번만 Build 되고 화면은 계속 유지된다.

 

class MyHomePage extends StatefulWidget {
MyHomePage({Key? key, required this.title}) : super(key: key);

// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.

// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".

final String title;

@override
_MyHomePageState createState() => _MyHomePageState();
}
   # 데이터의 변화가 있고 유동적으로 사용되는 Widget
   # setState가 발생할때마다 Build과정이 일어난다. ( state를 포함 )