fluttrer 列表学习
import 'dart:math';
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: const MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
List<String> items = List.generate(10, (int i) => '$i' + "10");
List<String> items2 = List.generate(10, (int i) => '$i' + "1000");
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: _createListView2() , // This trailing comma makes auto-formatting nicer for build methods.
);
}
Widget _createListView2() {
Widget widget = ListView.builder(itemBuilder: (context, index) {
if (index == 0 || index == 2) {
return Container(
key: ValueKey("$index"),
color: Colors.white,
height: 80,
width: double.infinity,
child: Text("$index分类行",style: const TextStyle(color: Colors.black,fontSize: 20),),
);
} else {
return Container(
height: 56 * 10,
child: _createReorderableListView(index == 1 ? 0 : 1),
);
}
} , itemCount: 4);
return widget;
}
Widget _createRenderTable() {
Widget widget = CustomScrollView(
slivers:[
SliverReorderableList(itemBuilder: (context, index) {
return Container(
key: ValueKey("$index + w"),
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
height: 56,
width: double.infinity,
child: Text("第$index行",style: const TextStyle(color: Colors.red,fontSize: 20),),
);
}, itemCount: 5, onReorder: (int oldIndex, int newIndex) {
if (newIndex > oldIndex) {
newIndex -= 1;
}
}),
SliverReorderableList(itemBuilder: (context, index) {
return Container(
key: ValueKey("$index + k"),
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
height: 56,
width: double.infinity,
child: Text("第$index行",style: const TextStyle(color: Colors.red,fontSize: 20),),
);
}, itemCount: 5, onReorder: (int oldIndex, int newIndex) {
if (newIndex > oldIndex) {
newIndex -= 1;
}
}),
],
);
return widget;
}
Widget _createReorderableListView(int type) {
//SliverReorderableList
Widget widget = ReorderableListView.builder(key:ValueKey('$type' + 't'), itemBuilder: (context, index) {
return Container(
key: type == 0 ? ValueKey(items[index]) : ValueKey(items2[index]),
color: Colors.white,
height: 56,
width: double.infinity,
child: Text("第${type == 0 ? items[index] : items2[index]}行",style: const TextStyle(color: Colors.red,fontSize: 20),),
);
} , itemCount: 10,
onReorder: (int oldIndex, int newIndex) {
// if (newIndex > oldIndex) {
// newIndex -= 1;
// }
print(oldIndex);
print(newIndex);
var element = (type == 0 ? items[oldIndex] : items2[oldIndex]);
if (type == 0) {
if (newIndex >= items.length) {
newIndex = (items.length - 1);
}
} else {
if (newIndex >= items2.length) {
newIndex = (items2.length - 1);
}
}
setState(() {
if (type == 0) {
items.removeAt(oldIndex);
items.insert(newIndex, element);
} else {
items2.removeAt(oldIndex);
items2.insert(newIndex, element);
}
});
});
return widget;
}
Widget _createListView() {
Widget widget = ListView.builder(itemBuilder: (context, index) {
return Container(
key: ValueKey("$index"),
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
height: 56,
width: double.infinity,
child: Text("第$index行",style: const TextStyle(color: Colors.red,fontSize: 20),),
);
} , itemCount: 5);
return widget;
}
Widget _createMyScrollviewDemo03() {
Widget widget = CustomScrollView(
slivers:[
SliverList(delegate: SliverChildBuilderDelegate(
(BuildContext contetx, int index){
return Container(
height: 20,
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
);
},
childCount: 20,
)),
SliverList(delegate: SliverChildBuilderDelegate(
(BuildContext contetx, int index){
return Container(
height: 20,
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
);
},
childCount: 20,
)),
],
);
return widget;
}
Widget _createMyScrollviewDemo02() {
Widget widget = CustomScrollView(
slivers:[
SliverGrid(delegate: SliverChildBuilderDelegate(
// ignore: avoid_types_as_parameter_names, non_constant_identifier_names
(BuilderContext, int) {
return Container(
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
);
},
childCount: 20,
),
gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
crossAxisSpacing: 8,
mainAxisSpacing: 8,
childAspectRatio: 1.5
),),
SliverList(delegate: SliverChildBuilderDelegate(
(BuildContext contetx, int index){
return Container(
height: 56,
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
);
},
childCount: 20,
)),
],
);
return widget;
}
Widget _createMyScrollviewDemo01() {
Widget widget = CustomScrollView(
slivers:[ _createSliverGirdle()],
);
return widget;
}
Widget _createSliverGirdle() {
Widget widget = SliverSafeArea(
sliver: SliverPadding(padding:const EdgeInsets.only(top: 10),
sliver: SliverGrid(delegate: SliverChildBuilderDelegate(
// ignore: avoid_types_as_parameter_names, non_constant_identifier_names
(BuilderContext, int) {
return Container(
color: Color.fromARGB(255, Random().nextInt(256), Random().nextInt(256),Random().nextInt(256)),
);
},
childCount: 20,
),
gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
crossAxisSpacing: 8,
mainAxisSpacing: 8,
childAspectRatio: 1.5
),)
));
return widget;
}
}
