forEach method Null safety

void forEach(
  1. void action(
    1. K key,
    2. V value
    )
)
override

Applies action to each key/value pair of the map.

Calling action must not add or remove keys from the map.

final planetsByMass = <num, String>{0.81: 'Venus', 1: 'Earth',
  0.11: 'Mars', 17.15: 'Neptune'};

planetsByMass.forEach((key, value) {
  print('$key: $value');
  // 0.81: Venus
  // 1: Earth
  // 0.11: Mars
  // 17.15: Neptune
});

Implementation

void forEach(void action(K key, V value)) {
  for (K key in keys) {
    action(key, this[key] as V);
  }
}