Dart Map

// Map literal with inferred type Map<String, int>
var inferredMap = {'alpha': 1, 'beta': 2};

// Explicit generic type declaration
Map<String, dynamic> explicitMap = {
  'id': 101,
  'isActive': true,
};

// Constructor initialization
var emptyMap = Map<int, String>();

var config = {'retries': 3, 'timeout': 5000};

// Reading values
int? retries = config['retries']; // Returns 3
int? port = config['port'];       // Returns null

// Mutating values
config['port'] = 8080;            // Inserts a new key-value pair
config['retries'] = 5;            // Updates the value of an existing key

var data = {'a': 1, 'b': 2};

// Adds the key-value pair only if the key does not currently exist
data.putIfAbsent('c', () => 3);

// Updates the value for a key. Throws an error if the key doesn't exist 
// unless the optional ifAbsent callback is provided.
data.update('a', (value) => value + 10, ifAbsent: () => 10);

// Removes the key and its associated value, returning the removed value (V?)
int? removedValue = data.remove('b');

// Boolean checks for existence
bool hasKey = data.containsKey('a');     // true
bool hasValue = data.containsValue(99);  // false

// Clears all entries, resulting in an empty map
data.clear();

var metrics = {'cpu': 45, 'ram': 1024};

// Using the forEach method
metrics.forEach((key, value) {
  print('$key: $value');
});

// Using a for-in loop with MapEntry
for (MapEntry<String, int> entry in metrics.entries) {
  print('${entry.key}: ${entry.value}');
}