Java Persistence with Hibernate

4.2. Mapping entities with identity

It's vital to understand the difference between object identity and object equality before we discuss terms like database identity and the way Hibernate manages identity. Next, we explore how object identity and equality relate to database (primary key) identity.

4.2.1. Understanding Java identity and equality

Java developers understand the difference between Java object identity and equality. Object identity, ==, is a notion defined by the Java virtual machine. Two object references are identical if they point to the same memory location.

On the other hand, object equality is a notion defined by classes that implement the equals() method, sometimes also referred to as equivalence. Equivalence means that ...