Java Reflection Notes – getDeclaredAnnotations vs getAnnotations method
This is just going to be a very short notes about difference between the getDeclaredAnnotations and getAnnotations method of Java java.lang.Class
I was googling for the answer but didn’t immediately got any article that explains it, so I thought why I not create it myself.
So what is the difference:
In short:
– getAnnotations basically gets all annotations that are also inherited from the parent class.
– getDeclaredAnnotations gets annotations declared ONLY on the class
If you rather believe what the code says rather than me, here’s the code:
[java]
public class CheckTest {
@Retention(RetentionPolicy.RUNTIME)
@Inherited
public @interface CustomAnnotation{
String value();
}
@CustomAnnotation(“label”)
public static class Parent{
}
public static class Child extends Parent{
}
/**
* @param args
*/
public static void main(String[] args) {
Parent parent = new Parent();
Child child = new Child();
System.out.println(“Parent class:”);
System.out.println(” getDeclaredAnnotations: ” +
parent.getClass().getDeclaredAnnotations().length);
System.out.println(” getAnnotations: ” +
parent.getClass().getAnnotations().length + “\n”);
System.out.println(“Child class:”);
System.out.println(” getDeclaredAnnotations: ” +
child.getClass().getDeclaredAnnotations().length);
System.out.println(” getAnnotations: ” +
child.getClass().getAnnotations().length);
}
}
[/java]
The output result is:
Parent class:
getDeclaredAnnotations: 1
getAnnotations: 1
Child class:
getDeclaredAnnotations: 0
getAnnotations: 1
Notice that the Child getAnnotations array length is 0, because by itself the Child class doesn’t has annotations. 😀