Map<K, V>.from constructor Null safety

Map<K, V>.from(
  1. Map other

Creates a LinkedHashMap with the same keys and values as other.

The keys must all be instances of K and the values of V. The other map itself can have any type, unlike for Map.of, and the key and value types are checked (and can fail) at run-time.

Prefer using Map.of when possible, and only use Map.from to create a new map with more precise types than the original, and when it's known that all the keys and values have those more precise types.

A LinkedHashMap requires the keys to implement compatible operator== and hashCode. It iterates in key insertion order.

final planets = <num, String>{1: 'Mercury', 2: 'Venus', 3: 'Earth', 4: 'Mars'};
final mapFrom = Map<int, String>.from(planets);
print(mapFrom); // {1: Mercury, 2: Venus, 3: Earth, 4: Mars}


factory Map.from(Map other) = LinkedHashMap<K, V>.from;