Dart组件进度条仅在循环结束时更新

import 'package:flutter/material.dart';

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  double _progress = 0.0;

  // 模拟循环执行过程
  void _startLoop() {
    for (int i = 0; i < 100; i++) {
      // 执行任务
      // ...

      // 更新进度条
      setState(() {
        _progress = (i + 1) / 100;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            LinearProgressIndicator(value: _progress),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: _startLoop,
              child: Text('开始循环'),
            ),
          ],
        ),
      ),
    );
  }
}

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