Widget：https://flutter.io/docs/development/ui/widgets PopupMenuButton：https://docs.flutter.io/flutter/material/PopupMenuButton-class.html impo
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Widget：https://flutter.io/docs/development/ui/widgets DropdownButton：https://docs.flutter.io/flutter/material/DropdownButton-class.html import
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Widget：https://flutter.io/docs/development/ui/widgets TabBar：https://docs.flutter.io/flutter/material/TabBar-class.html TabBarView：https://docs.flutte
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Widget：https://flutter.io/docs/development/ui/widgets BottomNavigationBar：https://docs.flutter.io/flutter/material/BottomNavigationBar-class.html imp
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Widget：https://flutter.io/docs/development/ui/widgets AppBar：https://docs.flutter.io/flutter/material/AppBar-class.html import 'package:flutter/
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Widget：https://flutter.io/docs/development/ui/widgets RaisedButton：https://docs.flutter.io/flutter/material/RaisedButton-class.html FlatButton：https:/
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Widget：https://flutter.io/docs/development/ui/widgets Icon：https://docs.flutter.io/flutter/widgets/Icon-class.html import 'package:flutter/mater
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Widget：https://flutter.io/docs/development/ui/widgets Image：https://docs.flutter.io/flutter/widgets/Image-class.html import 'package:flutter/mat
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Widget：https://flutter.io/docs/development/ui/widgets Text：https://docs.flutter.io/flutter/widgets/Text-class.html import 'package:flutter/mater
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Widget：https://flutter.io/docs/development/ui/widgets Column：https://docs.flutter.io/flutter/widgets/Column-class.html import 'package:flutter/m
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Widget：https://flutter.io/docs/development/ui/widgets Row：https://docs.flutter.io/flutter/widgets/Row-class.html import 'package:flutter/materia
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Widget：https://flutter.io/docs/development/ui/widgets Container：https://docs.flutter.io/flutter/widgets/Container-class.html import 'package:flu
2023-03-16
Dart 语言并没有提供 interface 关键字，但是每一个类都隐式地定义了一个接口。 import 'dart:math'; abstract class Shape { factory Shape(String type) { if (type == &#
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定义Shape形状类，并输出其面积 Dart 支持抽象类，可以在一个文本中定义多个类 dart.math 是一个 Dart 核心库，其余的还有诸如 dart:core，dart:async，dart:convert 和 dart:collection 这样的核心库 import 'dar
2023-03-16
DartPad：https://dartpad.cn/ 创建一个简单的 Dart类 定义类、构造函数及实例化 class Bicycle { int cadence; int speed; int gear; Bicycle(this.cadence, this.speed, t
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