Flutter学习笔记&学习资料推荐，15分钟的字节跳动视频面试

children: [
FlatButton(onPressed: onToggle, child: Text(‘On’)),
FlatButton(onPressed: onToggle, child: Text(‘Off’)),
],
);
}
}

//…
Widget _toggleButton(String text) =>
FlatButton(onPressed: onToggle, child: Text(text));
@override
Widget build(BuildContext context) {
return Row(
children: [
_toggleButton(‘On’),
_toggleButton(‘Off’),
],
);
}

final List fruits;
//…
@override
Widget build(BuildContext context) {
return Column(
children: _buildChildren(),
);
}
List _buildChildren() {
return fruits.map((f) => _FruitInfo(fruit: f)).toList();
}

bool condition;
Widget _foo();
Widget _bar();
Widget build(BuildContext context) {
return condition
? _foo()_bar();
}

Widget functionA() => Container()
@override
Widget build() {
return functionA()
}
@override
Widget build() {
return Container();
}

class ClassA extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Container();
}
}
@override
Widget build() {
return ClassA()
}
@override
Widget build() {
return KeyedSubtree(
key: ObjectKey(ClassA),
child: Container(),
);
}

@swidget
Widget foo(BuildContext context, int value) {
return Text(‘$value’);
}

class Foo extends StatelessWidget {
const Foo(this.value, {Key key}) : super(key: key);
final int value;
@override
Widget build(BuildContext context) {
return foo(context, value);
}
@override
void debugFillProperties(DiagnosticPropertiesBuilder properties) {
super.debugFillProperties(properties);
properties.add(IntProperty(‘value’, value));
}
}

class Example extends StatefulWidget {
@override
_ExampleState createState() => _ExampleState();
}
class _ExampleState extends State {
Future future;
@override
void initState() {
future = Future.value(42);
super.initState();
}
@override
Widget build(BuildContext context) {
return FutureBuilder(
future: future,
builder: (context, snapshot) {
// create some layout here
},
);
}
}

@override
Widget build(BuildContext context) {
return const DecoratedBox(
decoration: BoxDecoration(),
child: Text(“Hello World”),
);
}

@override
Widget build(BuildContext context) {
final subtree = MyWidget(
child: Text(“Hello World”)
);
return StreamBuilder(
stream: stream,
initialData: “Foo”,
builder: (context, snapshot) {
return Column(
children: [
Text(snapshot.data),
subtree,
],
);
},
);
}

@override
void didUpdateWidget(MyRichText oldWidget) {
if (widget.text != oldWidget.text) {
_textSpan = parseText(widget.text);
}
super.didUpdateWidget(oldWidget);
}

@override
void didUpdateWidget(CounterWidget oldWidget) {
//通过新旧widget的一些属性来判断是否变化
// 检查新旧child是否发生变化(key和类型同时相等则返回true，认为没变化)
if (Widget.canUpdate(widget.child, oldWidget.child)) {
// child没变化，…
} else {
super.didUpdateWidget(oldWidget);
}
}

import ‘package:flutter/material.dart’;
import ‘column_row_wrap.dart’;
class UnNestLayoutTestPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text(“去除嵌套示例”),),
body: ColumnWidget()
.addChild(Text(“呵呵”))
.addChild(Text(“怎样”))
.addChildByPadding(Text(“可以”), EdgeInsets.all(10.0))
.addChild(CenterWidget(Text(“测试”)))
.addChild(RowWidget()
.addChild(Text(“你好”))
.addChildByMargin(Text(“很好”), EdgeInsets.all(20.0))
.addChild(Text(“大家好”)))
.addChild(ContainerWidget(Text(“中国”))
.addPadding(EdgeInsets.all(10.0))
.addDecoration(BoxDecoration(color: Colors.red)))
.addChild(RaisedButtonWrap(“提交”)
.textColor(Colors.blue)
.onClick(() => { print(“点击了提交”)}))
);
}
}

import ‘package:flutter/material.dart’;
class ColumnWidget extends StatelessWidget {
List _children = [];
ColumnWidget addChild(Widget widget) {
_children.add(widget);
return this;
}
ColumnWidget addChildByPadding(Widget widget, EdgeInsetsGeometry padding) {
_children.add(Padding(
child: widget,
padding: padding,
));
return this;
}
@override
Widget build(BuildContext context) {
return Column(
children: _children,
);
}
}
class RowWidget extends StatelessWidget {
List _children = [];
RowWidget addChild(Widget widget) {
_children.add(widget);
return this;
}
RowWidget addChildByMargin(Widget widget, EdgeInsetsGeometry margin) {
_children.add(Container(
child: widget,
margin: margin,
));
return this;
}
@override
Widget build(BuildContext context) {
return Row(
children: _children,
);
}
}
class ContainerWidget extends StatelessWidget {
final Widget children;
ContainerWidget(this.children);
EdgeInsetsGeometry _padding;
EdgeInsetsGeometry _margin;
Decoration _decoration;
ContainerWidget addPadding(EdgeInsetsGeometry padding) {
_padding = padding;
return this;
}
ContainerWidget addMargin(EdgeInsetsGeometry margin) {
_margin = margin;
return this;
}
ContainerWidget addDecoration(Decoration decoration) {
_decoration = decoration;
return this;
}
@override
Widget build(BuildContext context) {
return Container(
child: children,
padding: _padding,
margin: _margin,
decoration: _decoration,
);
}
}
class RaisedButtonWrap extends StatelessWidget {
String title;
RaisedButtonWrap(this.title);
Color _textColor;
Color _bgColor;
VoidCallback _clickListener;
RaisedButtonWrap onClick(VoidCallback clickListener) {
_clickListener = clickListener;
return this;
}
RaisedButtonWrap textColor(Color textColor) {
_textColor = textColor;
return this;
}
RaisedButtonWrap bgColor(Color bgColor) {
_bgColor = bgColor;
return this;
}
@override
Widget build(BuildContext context) {
return RaisedButton(
child: Text(title),
textColor: _textColor,
color: _bgColor,
onPressed: _clickListener,
);
}
}
class CenterWidget extends StatelessWidget {
final Widget child;
CenterWidget(this.child);
@override
Widget build(BuildContext context) {
return Center(
child: child,
);
}
}

class UnNestLayoutTestPage2 extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text(“去除嵌套示例”),),
body: ColumnWidget()
.addChild(Text(“测试”))
.addChild(Container(
child: RowWidget()
.addChild(Text(“你好”))
.addChildByMargin(Text(“很好”), EdgeInsets.all(20.0))
.addChild(Text(“大家好”)),
))
.addChild(Container(
child:Center(
child: RaisedButtonWrap(“提交”)
.textColor(Colors.blue)
.onClick(() => { print(“点击了提交”)}),
),
))
);
}
}