一、Records概述

Records是Dart 3引入的不可变数据类型，用于组合多个值。

|| 特性 | 说明 |
|------|------|
| 不可变性 | 创建后不能修改 |
| 结构相等 | 值相等而非引用相等 |
| 命名字段 | 支持命名和位置字段 |
| 模式匹配 | 支持解构和匹配 |

二、示例代码

class _Page03RecordsDemo extends StatefulWidget {
  const _Page03RecordsDemo();

  @override
  State<_Page03RecordsDemo> createState() => _Page03RecordsDemoState();
}

class _Page03RecordsDemoState extends State<_Page03RecordsDemo> {
  final List<({String name, int score, Color color})> _scores = [
    (name: '数学', score: 95, color: Colors.blue),
    (name: '英语', score: 88, color: Colors.green),
    (name: '科学', score: 92, color: Colors.orange),
  ];

  void _addRandomScore() {
    final subjects = ['数学', '英语', '科学', '历史', '艺术'];
    final colors = [Colors.blue, Colors.green, Colors.orange, Colors.purple, Colors.pink];
    final random = DateTime.now().millisecond;

    setState(() {
      _scores.add((
        name: subjects[random % subjects.length],
        score: 60 + (random % 40),
        color: colors[random % colors.length],
      ));
    });
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.blue.shade50,
      padding: const EdgeInsets.all(20),
      child: Column(
        children: [
          Container(
            padding: const EdgeInsets.all(20),
            decoration: BoxDecoration(
              color: Colors.blue.shade600,
              borderRadius: BorderRadius.circular(20),
            ),
            child: const Column(
              children: [
                Icon(Icons.sticky_note_2, size: 48, color: Colors.white),
                SizedBox(height: 16),
                Text(
                  'Records记录',
                  style: TextStyle(fontSize: 28, fontWeight: FontWeight.bold, color: Colors.white),
                ),
                SizedBox(height: 8),
                Text('不可变数据结构 - 页面 3/5', style: TextStyle(color: Colors.white70)),
              ],
            ),
          ),
          const SizedBox(height: 24),
          Expanded(
            child: Container(
              padding: const EdgeInsets.all(20),
              decoration: BoxDecoration(color: Colors.white, borderRadius: BorderRadius.circular(20)),
              child: Column(
                children: [
                  Expanded(
                    child: ListView.builder(
                      itemCount: _scores.length,
                      itemBuilder: (context, index) {
                        final score = _scores[index];
                        return Card(
                          margin: const EdgeInsets.only(bottom: 8),
                          child: ListTile(
                            leading: Container(
                              width: 40,
                              height: 40,
                              decoration: BoxDecoration(
                                color: score.color,
                                borderRadius: BorderRadius.circular(8),
                              ),
                              child: Center(
                                child: Text(
                                  score.score.toString(),
                                  style: const TextStyle(color: Colors.white, fontWeight: FontWeight.bold),
                                ),
                              ),
                            ),
                            title: Text(score.name),
                            subtitle: Text('分数: ${score.score}'),
                          ),
                        );
                      },
                    ),
                  ),
                  ElevatedButton(
                    onPressed: _addRandomScore,
                    style: ElevatedButton.styleFrom(backgroundColor: Colors.blue.shade600),
                    child: const Text('添加成绩', style: TextStyle(color: Colors.white)),
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}

三、Records优势

四、应用场景

五、最佳实践

• ✅ 使用命名字段提高可读性
• ✅ 合理使用解构
• ✅ 保持Records简洁
• ❌ 避免嵌套过深

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