问题描述
我有一个非常简单的 BottomNavigationBar
。我想要完成的是,当我转到另一个选项卡时,body 属性的内容会发生变化,即每个选项卡都有自己的小部件要显示。因此,当索引更改时,我尝试更改 body
属性,但我无法弄清楚如何做到这一点。
主要代码如下:
class _MyHomeState extends State<MyHome> {
HomeBody obj; //A class that returns a widget according to the index
@override
Widget build(BuildContext context) {
return Scaffold(
body: obj.selectHomeBody(),bottomNavigationBar: MyBotNavBar(),);
}
}
我的底部导航栏小部件,
class _MyBotNavBarState extends State<MyBotNavBar> {
int _curIdx = 0;
@override
Widget build(BuildContext context) {
return BottomNavigationBar(
items: getBotNavListItems(),currentIndex: curIdx,onTap: (int index) {
setState(() {
_curIdx = index;
});
},);
}
}
下面的类应该根据索引返回一个小部件,
class HomeBody {
final int _idx = _MyBotNavBarState().curIdx;
Widget selectHomeBody() {
Widget widget; //the widget that will be returned
//There might be more cases
switch (_idx) {
case 0:
{
widget = getHome();
break;
}
default:
{
widget = getSchool();
break;
}
}
return widget;
}
//defining those widgets
Widget getHome() {
return Center(
child: Text("$_idx Home"),);
}
Widget getBusiness() {
return Center(
child: Text("$_idx Business"),);
}
}
解决方法
如果我当时就理解你的问题。
您应该先参考 flutter 文档,这是文档本身的演示。
import 'package:flutter/material.dart';
void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return const MaterialApp(
home: MyStatefulWidget(),);
}
}
class MyStatefulWidget extends StatefulWidget {
const MyStatefulWidget({Key? key}) : super(key: key);
@override
State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
int _selectedIndex = 0;
static const List<Widget> _widgetOptions = <Widget>[
Text('Page1'),Text('Page2'),Text('Page3'),];
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('BottomNavigationBar Sample'),),body: Center(
child: _widgetOptions.elementAt(_selectedIndex),bottomNavigationBar: BottomNavigationBar(
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(Icons.home),label: 'Page1',BottomNavigationBarItem(
icon: Icon(Icons.business),label: 'Page2',BottomNavigationBarItem(
icon: Icon(Icons.school),label: 'Page3',],currentIndex: _selectedIndex,selectedItemColor: Colors.amber[800],onTap: _onItemTapped,);
}
}
因此,他们在这里创建了您想要显示的小部件列表 _widgetOptions
,然后他们更改了 _selectedIndex
的值并重新呈现 UI 以进行必要的更改。
这是该文章的链接BottomNavigationBar