Is it possible to make a Java annotation's value mandatory?

Question

Java allows the definition of values in annotations, for example:

public @interface MyAnnotation {
    int MyValue();
}

Although it is possible to set a default value for the MyValue annotation, I was wondering whether it is possible to make it mandatory. What I mean is forcing the user to provide a value for MyValue when annotating a class or field.

I went through the documentation but could not find anything. Does anyone have a solution to this issue or is it just impossible to make an annotation's value mandatory?

It should be noted that the return type of `MyValue` is only permitted to be a "primitive type, String, Class, annotation, enumeration...or 1-dimensional arrays thereof." — Vessel, Apr 02 '23 at 02:18

score 107 · Accepted Answer · answered Aug 15 '11 at 20:19

107

If you do not specify a default value, it is mandatory. For your example using your annotation without using the MyValue attribute generates this compiler error:

annotation MyAnnotation is missing MyValue

answered Aug 15 '11 at 20:19

Stefan Schubert-Peters

5,419
2
20
21

score 11 · Answer 2 · edited Feb 18 '20 at 08:46

11

Given

public @interface MyAnnotation {
    int MyValue();
}

a class

@MyAnnotation
public class MyClass {

}

will be a compile error without a value.

edited Feb 18 '20 at 08:46

oligofren

20,744
16
93
180

answered Aug 15 '11 at 20:22

Clint

8,988
1
26
40

score 0 · Answer 3 · answered Mar 15 '12 at 02:42

0

I haven't tried this but if you are wanting to force the values to a specific value perhaps making the type an enum.

public @interface MyAnnotation {
    Status status();
}

Where Status is an enum.

answered Mar 15 '12 at 02:42

Yargis

17
1

Is it possible to make a Java annotation's value mandatory?

3 Answers3