CODEWITHSUNDEEP
javareflectionannotations
Jin Kwon
Jin Kwon

Reputation: 21978

How to get annotation elements' default value?

Let's say I have an Annotation.

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface MyAnnotation {
    int value() default 1;
}

Is there any way to get the value of 1 using reflection or something?

Upvotes: 4

Views: 2309

Answers (2)

Sotirios Delimanolis
Sotirios Delimanolis

Reputation: 279960

Yes, you can use Method#getDefaultValue() which

Returns the default value for the annotation member represented by this Method instance.

Take the following example

public class Example {
    public static void main(String[] args) throws Exception {
        Method method = Example.class.getMethod("method");
        MyAnnotation annot = method.getAnnotation(MyAnnotation.class);
        System.out.println(annot.value()); // the value of the attribute for this method annotation
        Method value = MyAnnotation.class.getMethod("value");
        System.out.println(value.getDefaultValue()); // the default value
    }

    @MyAnnotation(42)
    public static void method() {

    }
}

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
@interface MyAnnotation {
    int value() default 1;
}

it prints

42
1

Upvotes: 2

Pshemo
Pshemo

Reputation: 124225

How about

MyAnnotation.class.getMethod("value").getDefaultValue()

Upvotes: 5

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