Collections Methods trong Dart

🎯 Mục tiêu: Functional operations trên collections.

💡 Transform


var numbers = [1, 2, 3, 4, 5];
 
var doubled = numbers.map((n) => n * 2).toList();  // [2, 4, 6, 8, 10]
var flat = [[1,2], [3,4]].expand((x) => x).toList(); // [1, 2, 3, 4]

📝 Filter


var numbers = [1, 2, 3, 4, 5, 6];
 
var evens = numbers.where((n) => n % 2 == 0).toList();  // [2, 4, 6]
var first = numbers.firstWhere((n) => n > 3);  // 4
var last = numbers.lastWhere((n) => n < 5);    // 4

🔧 Aggregate


var numbers = [1, 2, 3, 4, 5];
 
numbers.reduce((a, b) => a + b);  // 15
numbers.fold(10, (a, b) => a + b); // 25
 
numbers.any((n) => n > 3);   // true
numbers.every((n) => n > 0); // true

🎯 Chaining


var result = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    .where((n) => n % 2 == 0)
    .map((n) => n * n)
    .take(3)
    .toList();  // [4, 16, 36]

✅ Checklist

map, where, reduce, fold
any, every
Chain multiple operations