Are Java Collections Immutable?

Collections are all immutable, but implement java collections interfaces (and generics) for inspection. Mutation returns new collections.

Is Java collection mutable?

If you're wondering about java. util. ArrayList - it is mutable and it is not creating another List instance on add() or remove() . If you are looking for immutable list - check Guava implementation of ImmutableList or Collections.

Is Java list immutable?

The List, Set, or Map returned by the of() static factory method is structurally immutable, which means you cannot add, remove, or change elements once added. Calling any mutator method will always cause an UnsupportedOperationException to be thrown.