Value-based Classes

Some classes, such as java.lang.Integer and java.time.LocalDate, are value-based. A value-based class has the following properties:

When two instances of a value-based class are equal (according to `equals`), a program should not attempt to distinguish between their identities, whether directly via reference equality or indirectly via an appeal to synchronization, identity hashing, serialization, or any other identity-sensitive mechanism.

Synchronization on instances of value-based classes is strongly discouraged, because the programmer cannot guarantee exclusive ownership of the associated monitor.

Identity-related behavior of value-based classes may change in a future release. For example, synchronization may fail.