从ListView中的实例调用setState

import 'package:flutter/material.dart';

class MyListView extends StatefulWidget {
  @override
  _MyListViewState createState() => _MyListViewState();
}

class _MyListViewState extends State<MyListView> {
  List<String> items = ['Item 1', 'Item 2', 'Item 3'];

  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: items.length,
      itemBuilder: (BuildContext context, int index) {
        return ListTile(
          title: Text(items[index]),
        );
      },
    );
  }

  void updateListView() {
    setState(() {
      // 修改items列表
      items.add('New Item');
    });
  }
}

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      appBar: AppBar(
        title: Text('ListView Example'),
      ),
      body: MyListView(),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          // 点击按钮调用setState
          MyListView().updateListView();
        },
        child: Icon(Icons.add),
      ),
    ),
  ));
}