description

# Map<K, V>.unmodifiable constructor

Map<K, V>.unmodifiable(

1. 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 compatible `operator==` 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);