How do I use the JPA Criteria API for querying?

How do I use the JPA Criteria API for querying in my Java application?

The JPA Criteria API allows you to build queries programmatically using Java objects. You can create a CriteriaBuilder instance from your EntityManager, then use it to construct CriteriaQuery objects.

Can you give me an example of a simple query using the Criteria API?

Sure! Here's a basic example:

CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Employee> query = cb.createQuery(Employee.class);
Root<Employee> root = query.from(Employee.class);
query.select(root).where(cb.equal(root.get("department"), "Sales"));
List<Employee> results = entityManager.createQuery(query).getResultList();

What are the advantages of using the Criteria API over JPQL?

The Criteria API is type-safe, allows for dynamic query generation, and integrates well with Java's object-oriented features, making it easier to build complex queries.

Are there any performance considerations I should be aware of?

Yes, while the Criteria API is powerful, it can lead to more complex queries that may impact performance. Always analyze the generated SQL and optimize as needed.