Multiple annotations of the same type on one element?

Question

I\'m attempting to slap two or more annotations of the same type on a single element, in this case, a method. Here\'s the approximate code that I\'m working with:

Answer 1

If you have only 1 parameter "bar" you can name it as "value". In this case you wont have to write the parameter name at all when you use it like this:

@Foos({@Foo("one"), @Foo("two")})
public void haha() {}

a bit shorter and neater, imho..

Answer 2

combining the other answers into the simplest form ... an annotation with a simple list of values ...

@Foos({"one","two"})
private String awk;

//...

public @interface Foos{
    String[] value();
}

Answer 3

Apart from the other ways mentioned, there is one more less verbose way in Java8:

@Target(ElementType.TYPE)
@Repeatable(FooContainer.class)
@Retention(RetentionPolicy.RUNTIME)
@interface Foo {
    String value();

}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@interface FooContainer {
        Foo[] value();
        }

@Foo("1") @Foo("2") @Foo("3")
class Example{

}

Example by default gets, FooContainer as an Annotation

    Arrays.stream(Example.class.getDeclaredAnnotations()).forEach(System.out::println);
    System.out.println(Example.class.getAnnotation(FooContainer.class));

Both the above print:

@com.FooContainer(value=[@com.Foo(value=1), @com.Foo(value=2), @com.Foo(value=3)])

@com.FooContainer(value=[@com.Foo(value=1), @com.Foo(value=2), @com.Foo(value=3)])

Answer 4

Repeating annotations in Java 8

In Java 8 (released in March 2014), it is possible to write repeated/duplicate annotations.

See tutorial, Repeating Annotations.

See specification, JEP 120: Repeating Annotations.

Answer 5

http://docs.oracle.com/javase/tutorial/java/annotations/repeating.html

Starting from Java8 you can describe repeatable annotations:

@Repeatable(FooValues.class)
public @interface Foo {
    String bar();
}

public @interface FooValues {
    Foo[] value();
}

Note, value is required field for values list.

Now you can use annotations repeating them instead of filling the array:

@Foo(bar="one")
@Foo(bar="two")
public void haha() {}

Answer 6

In the current version of Java, I was able to resolve this issue with the following annotation:

@Foo({"one", "two"})