javacollectionsreferenceequals

Collection using reference equality

In Java is it possible to create HashMap that uses reference equality (i.e. ==) instead of the equals() method?

Solution

  • Use the IdentityHashMap class. This is a variant of HashMap in which == and System.identityHashCode() are used instead of Object.equals(Object) and Object.hashCode().

    Note that this class intentionally violates the API contract of java.util.Map which requires that key equality is based on equals(Object).