@Singleton class do I have to make constructor private

Question

I'm writing a Singleton class in Java EE 6 using the @Singleton annotation. I have not declared a constructor.

Do I have to create a private constructor explicitly?

The reason I'm asking is that I'm using PMD and the rule UseSingleton is flagged. I think that PMD does not understand the annotation @Singleton?

Answer 1

PMD is recommending making the constructor private so that others may not instantiate your singleton object. It's unaware of Java EE 6 annotations.

You can safely ignore this warning.

Answer 2

No. Just add @Singleton on the bean class.

@Singleton
public class TesterBean {
  private int testCount = 0;
    public int getCount() {
      return testCount++;
    }
}