如何在flutter中获取列表中选定项的值

import 'package:flutter/material.dart';

class ListItem {
  String value;
  bool isSelected;

  ListItem({required this.value, this.isSelected = false});
}

class MyListPage extends StatefulWidget {
  @override
  _MyListPageState createState() => _MyListPageState();
}

class _MyListPageState extends State<MyListPage> {
  List<ListItem> items = [
    ListItem(value: 'Item 1'),
    ListItem(value: 'Item 2'),
    ListItem(value: 'Item 3'),
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('List Example'),
      ),
      body: ListView.builder(
        itemCount: items.length,
        itemBuilder: (context, index) {
          return ListTile(
            title: Text(items[index].value),
            onTap: () {
              setState(() {
                items[index].isSelected = !items[index].isSelected;
              });
            },
            tileColor: items[index].isSelected ? Colors.blue : null,
          );
        },
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          List<String> selectedValues = [];
          for (var item in items) {
            if (item.isSelected) {
              selectedValues.add(item.value);
            }
          }
          print('Selected Values: $selectedValues');
        },
        child: Icon(Icons.check),
      ),
    );
  }
}

void main() {
  runApp(MaterialApp(
    home: MyListPage(),
  ));
}