是否可以强制使用 Java 注释的值？

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?

Answer 1

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

Answer 2

Given

public @interface MyAnnotation {
    int MyValue();
}

a class

@MyAnnotation
public class MyClass {

}

will be a compile error without a value.

Answer 3

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.