The entity lifecycle model is one of the core concepts of JPA and all its implementations. Even though it’s not directly visible when working with JPA’s EntityManager, it affects all operations you perform. The different states of the model define how your persistence provider, e.g. Hibernate, handles your entity objects. This includes if it loads…
An association between 3 entities is called a ternary association. A typical example is an association between an employee, the project they are working on, and their role in that project. If the role is a complex object, you might decide to model this as 3 entity classes. The association between them is the interesting…
Every framework has a set of exceptions that indicate common error scenarios. Understanding them will help you turn a task that could drag along for days into a quickly-implemented feature. When working with Hibernate, they tell you about issues with your database queries, mapping mistakes, and problems during write operations. In this article, I want…
Using JPA’s and Hibernate’s 2nd level cache can improve the performance of your persistence layer. It acts as a session-independent entity store. Hibernate uses it whenever you call the find method on your EntityManager or traverse an association to fetch a cached entity. Instead of executing a database query, Hibernate gets the entity object from…
Lombok is a popular framework among Java developers because it generates repetitive boilerplate code like getter and setter methods, equals and hashCode methods, and the default constructor. All you need to do is add a few annotations to your class and Lombok will add the required code at compile time. This works reasonably well for…
