Map.unmodifiable constructor - Map - dart:core library (original) (raw)
Map<K, V>.unmodifiable(
- Map other )
Creates an unmodifiable hash-based map containing the entries of other
.
The keys must all be instances of K
and the values of V
. The other
map itself can have any type.
The map requires the keys to implement compatibleoperator==
and hashCode
. The created map iterates keys in a fixed order, preserving the order provided by other
.
The resulting map behaves like the result of Map.from, except that the map returned by this constructor is not modifiable.
final planets = <int, String>{1: 'Mercury', 2: 'Venus', 3: 'Earth'};
final unmodifiableMap = Map.unmodifiable(planets);
unmodifiableMap[4] = 'Mars'; // Throws
Implementation
external factory Map.unmodifiable(Map<dynamic, dynamic> other);