In Java, an immutable class refers to a class that cannot be modified after its creation. Some of the ways of creating an immutable class are:  Declare the class as final to avoid the creation of child classes.  Declare the data members present in the class as final to ensure that the values do not change after the creation of the objects.  Declare the data members present in the class as private in order to prevent direct access. Perform a deep copy of different objects to return a copy and not the real object reference.