@NotNull constraint for primitives, why?

Question

Just encountered a bug, where the issue was that i had:

@Column(name = "ACTIVE")
@NotNull
private boolean active;

In my code I had forgot to set the value but it still "worked" as the default of boolean is false. I have now changed it to Boolean so that it fails the validation if it is not actively set.

Why am I allowed to have @NotNull constraints to things that can obviously not be null? Is it refactoring reasons, so if i change to Boolean as i have done now, i still keep the intended constraint?

Are there any good ideas catch these issues (except more tests for just this purpose)? Or should i keep away from using primitives?

Answer 1

As javadoc says The annotated element must not be null. Accepts any type.

It can be any type it just checks whether the variable is not null or not, it has nothing to do with whether it accepts null or not.

As mentioned it is applicable for METHOD,FIELD,ANNOTATION_TYPE,CONSTRUCTOR,PARAMETER.

@Target(value={METHOD,FIELD,ANNOTATION_TYPE,CONSTRUCTOR,PARAMETER})