Async/Await trong Dart

🎯 Mục tiêu: Asynchronous programming với async/await.

💡 Cú pháp cơ bản


Future<String> fetchData() async {
  await Future.delayed(Duration(seconds: 1));
  return "Data loaded";
}
 
void main() async {
  print("Loading...");
  var data = await fetchData();
  print(data);
}

📝 Error Handling


Future<void> loadData() async {
  try {
    var data = await fetchData();
    print(data);
  } catch (e) {
    print("Error: $e");
  } finally {
    print("Done");
  }
}

🔧 Parallel execution


var results = await Future.wait([
  fetchUsers(),
  fetchPosts(),
  fetchComments(),
]);

📱 Trong Flutter


class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}
 
class _MyWidgetState extends State<MyWidget> {
  String? data;
  bool isLoading = true;
  
  @override
  void initState() {
    super.initState();
    _loadData();
  }
  
  Future<void> _loadData() async {
    try {
      var result = await fetchData();
      setState(() {
        data = result;
        isLoading = false;
      });
    } catch (e) {
      setState(() => isLoading = false);
    }
  }
}

✅ Checklist

async trên function, await khi gọi Future
Try-catch cho error handling
Future.wait cho parallel execution