颤动:将下拉按钮转换为Listview.builder

import 'package:flutter/material.dart';

class MyDropdownButton extends StatefulWidget {
  @override
  _MyDropdownButtonState createState() => _MyDropdownButtonState();
}

class _MyDropdownButtonState extends State<MyDropdownButton> {
  String selectedOption;

  List<String> options = [
    'Option 1',
    'Option 2',
    'Option 3',
    'Option 4',
    'Option 5',
  ];

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('DropdownButton to ListView.builder'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            DropdownButton(
              value: selectedOption,
              items: options.map((String option) {
                return DropdownMenuItem(
                  value: option,
                  child: Text(option),
                );
              }).toList(),
              onChanged: (String newValue) {
                setState(() {
                  selectedOption = newValue;
                });
              },
            ),
            SizedBox(height: 20),
            selectedOption != null
                ? Expanded(
                    child: ListView.builder(
                      itemCount: options.length,
                      itemBuilder: (BuildContext context, int index) {
                        return ListTile(
                          title: Text(options[index]),
                          onTap: () {
                            setState(() {
                              selectedOption = options[index];
                            });
                          },
                        );
                      },
                    ),
                  )
                : Container(),
          ],
        ),
      ),
    );
  }
}

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