Futures

🎯 Mục tiêu: Hiểu Future - async operations returning single value.

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💡 Tạo Future

// Từ value
Future<int> future1 = Future.value(42);

// Delayed
Future<String> future2 = Future.delayed(
  Duration(seconds: 1),
  () => "Done"
);

// Async function
Future<String> fetchData() async {
  await Future.delayed(Duration(seconds: 1));
  return "Data";
}

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📝 .then() và .catchError()

fetchData()
    .then((data) => print(data))
    .catchError((error) => print("Error: $error"))
    .whenComplete(() => print("Done"));

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🔧 Future.wait

var futures = [
  Future.delayed(Duration(seconds: 1), () => 1),
  Future.delayed(Duration(seconds: 2), () => 2),
];

var results = await Future.wait(futures);  // [1, 2]

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✅ Checklist

• Future cho single async value
• await hoặc .then() để get value
• Future.wait cho parallel

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