问题

我是新学习Flutter的，制作了一个具有两个轮廓按钮的应用，在特定条件下这两个按钮会启用或禁用。当按钮启用或禁用时会有短暂的延迟。问题如下：

如何去除这个延迟？我希望按钮能立即启用或禁用。有什么建议吗？

我正在模拟器上运行这个应用。

答案1

得分: 1

您可以根据按钮是否禁用/启用来传递不同的键。

```dart
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData.dark(
        useMaterial3: true,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int number = 0;

  void _onRemovePressed() {
    setState(() {
      number--;
    });
  }

  void _onAddPressed() {
    setState(() {
      number++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text('Demo'),
      ),
      body: Center(
        child: Column(
          children: [
            Text(
              number.toString(),
              style: Theme.of(context).textTheme.headlineMedium,
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                OutlinedButton(
                  key: number <= 0 ? null : const ValueKey('RemoveButton'),
                  onPressed: number <= 0 ? null : _onRemovePressed,
                  child: const Text('Remove'),
                ),
                OutlinedButton(
                  onPressed: _onAddPressed,
                  child: const Text('Add'),
                )
              ],
            ),
          ],
        ),
      ),
    );
  }
}

<details>
<summary>英文:</summary>

You can pass different key to the outlined button in case button is disabled/enabled.

```dart
import &#39;package:flutter/material.dart&#39;;

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: &#39;Flutter Demo&#39;,
      theme: ThemeData.dark(
        useMaterial3: true,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State&lt;MyHomePage&gt; createState() =&gt; _MyHomePageState();
}

class _MyHomePageState extends State&lt;MyHomePage&gt; {
  int number = 0;

  void _onRemovePressed() {
    setState(() {
      number--;
    });
  }

  void _onAddPressed() {
    setState(() {
      number++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: const Text(&#39;Demo&#39;),
      ),
      body: Center(
        child: Column(
          children: [
            Text(
              number.toString(),
              style: Theme.of(context).textTheme.headlineMedium,
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: [
                OutlinedButton(
                  key: number &lt;= 0 ? null : const ValueKey(&#39;RemoveButton&#39;),
                  onPressed: number &lt;= 0 ? null : _onRemovePressed,
                  child: const Text(&#39;Remove&#39;),
                ),
                OutlinedButton(
                  onPressed: _onAddPressed,
                  child: const Text(&#39;Add&#39;),
                )
              ],
            ),
          ],
        ),
      ),
    );
  }
}