Using Enum in your entity beans

It is quite handy to use an Enum, especially with type String. This means that the enum will be translated as a text field in your database.

Imagine the following Entity Simple.java:

@Entity
public class Simple {
  Process process;
 
  @Enumerated(EnumType.STRING)
  public void Process getProcess() {
      return process;
  }
}

And Process.java:

public enum Process {
  WHAT,
  THE,
  BUCK
}

Now, I initally thought, that since you are defining the enum type to be string, then you can simply query the database using string as well like this:

entityManager.createQuery("from Simple s where s.process=:process").setParameter("process","WHAT").getResultList();

However this doesn't work. You will need to use an Enum type. So the solution is to use Enum.valueOf()

entityManager.createQuery("from Simple s where s.process=:process").setParameter("process",Process.valueOf("WHAT")).getResultList();

Now the query will run and return your list :-)