Are Maps Immutable in Java

ImmutableMap, as suggested by the name, is a type of Map which is immutable. It means that the content of the map are fixed or constant after declaration, that is, they are read-only. If any attempt made to add, delete and update elements in the Map, UnsupportedOperationException is thrown.

Are maps mutable?

Maps are also called Hash tables. There are two kinds of Maps, the immutable and the mutable. The difference between mutable and immutable objects is that when an object is immutable, the object itself can’t be changed.

Is Java HashMap immutable?

If we want to use any class as a key in a hashmap then it should be immutable. If it is not possible then you need to make sure that once the class instance is created it is not modifying those instance properties which participate in the hashcode() calculation and equality check.