在BottomNavigationBar上调用所选索引的小部件的initState

import 'package:flutter/material.dart';

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _currentIndex = 0; // 当前选中的索引
  List<Widget> _pages = [
    // 不同选项卡对应的小部件列表
    FirstPage(),
    SecondPage(),
    ThirdPage(),
  ];

  @override
  void initState() {
    super.initState();
    _initCurrentPage();
  }

  void _initCurrentPage() {
    // 根据当前选中的索引调用对应页面的initState
    _pages[_currentIndex].initState();
  }

  void _onTabTapped(int index) {
    setState(() {
      _currentIndex = index; // 更新选中的索引
      _initCurrentPage(); // 调用当前选中页面的initState
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Bottom Navigation Bar'),
      ),
      body: _pages[_currentIndex], // 根据当前选中的索引显示对应页面
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _currentIndex, // 当前选中的索引
        onTap: _onTabTapped, // 点击选项卡时的回调函数
        items: [
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'First',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.search),
            label: 'Second',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.person),
            label: 'Third',
          ),
        ],
      ),
    );
  }
}

class FirstPage extends StatefulWidget {
  @override
  _FirstPageState createState() => _FirstPageState();
}

class _FirstPageState extends State<FirstPage> {
  @override
  void initState() {
    super.initState();
    // 初始化操作
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('First Page'),
    );
  }
}

class SecondPage extends StatefulWidget {
  @override
  _SecondPageState createState() => _SecondPageState();
}

class _SecondPageState extends State<SecondPage> {
  @override
  void initState() {
    super.initState();
    // 初始化操作
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('Second Page'),
    );
  }
}

class ThirdPage extends StatefulWidget {
  @override
  _ThirdPageState createState() => _ThirdPageState();
}

class _ThirdPageState extends State<ThirdPage> {
  @override
  void initState() {
    super.initState();
    // 初始化操作
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: Text('Third Page'),
    );
  }
}