Q:

What to use: JPQL or Criteria API?

My Java application is using JPA for object persistence. The business domain is very simple (just three classes are persistent, with 3-5 properties in each). Queries are simple as well. The question is which approach I should use: JPQL or Criteria API?

A:

I'm pretty sure this has already been covered here on SO but I couldn't find the existing  question. So, here is my point of view on the question:

I find JPQL queries easier to write/read. 
I find the Criteria API nice for building dynamic queries.

Which is basically what you'll find in Hibernate: Criteria vs. HQL. 
But there is one major difference between the JPA 2.0 Criteria API and the Hibernate's Criteria API that is worth mentioning: the JPA 2.0 Criteria API is a typesafe API and thus gives compile time checks, code completion, better refactoring support, etc. 
However, I don't find that the benefits outweighs the ease of use of JPQL.
To sum up, I would favor JPQL, except for dynamic queries (e.g. for multi criteria search features).
Related questions

Hibernate: Criteria vs. HQL
What are some of the real world example where JPA2 Criteria API is more preferable?

More resources

Hibernate Querying 102 : Criteria API

A:

I answered a similar question previously and I will re-post my answer here for the benefit of the community. I'm going to assume you are using an Application Server vis-a-vis my answer below.
The Criteria API exists to allow for the construction of dynamic SQL queries in a type-safe manner that prevents SQL injection. Otherwise you would be concatenating SQL strings together which is both error prone and a security risk: i.e. SQL Injection. That would be the only time you would want to use the Criteria API.
If the query remains basically the same but need only accept different parameters you should use annotated @NamedQueries which are simpler, precompiled, can be cached within the secondary cache and possibly validated during server startup.
That's basically the the rule of thumb concerning Criteria Queries versus @NamedQueries. In my experience rarely do you require the Criteria API but it is good that it exists for those rare times it is required.
Hope this helps.

