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Java Reflection - Method.getDeclaredAnnotationsByType() Examples

Java Reflection Java Java API 

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Class:

java.lang.reflect.Field

java.lang.Objectjava.lang.Objectjava.lang.reflect.AccessibleObjectjava.lang.reflect.AccessibleObjectjava.lang.reflect.AnnotatedElementAnnotatedElementjava.lang.reflect.Executablejava.lang.reflect.Executablejava.lang.reflect.MemberMemberjava.lang.reflect.GenericDeclarationGenericDeclarationjava.lang.reflect.Methodjava.lang.reflect.MethodLogicBig

Method:

public <T extends Annotation> T[] getDeclaredAnnotationsByType(Class<T> annotationClass)

Returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present.


Examples


package com.logicbig.example.method;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Method;
import java.util.Arrays;

public class GetDeclaredAnnotationsByTypeExample {
    private static class Test {
        @Deprecated
        @Async
        public void process() {
        }
    }

    public static void main(String... args) throws NoSuchMethodException {
        Method m = Test.class.getDeclaredMethod("process");
        Async[] a = m.getDeclaredAnnotationsByType(Async.class);
        System.out.println(a.length);
        Arrays.stream(a).forEach(System.out::println);
    }

    @Target({ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    private @interface Async {}

}

Output

1
@com.logicbig.example.method.GetDeclaredAnnotationsByTypeExample$Async()




package com.logicbig.example.method;

import java.lang.annotation.*;
import java.lang.reflect.Method;
import java.util.Arrays;

public class GetDeclaredAnnotationsByTypeExample2 {

    private static class Test {
        @Access("SUPER_USER")
        @Access("CUSTOMER")
        public void process() {
        }
    }

    public static void main(String... args) throws NoSuchMethodException {
        Method m = Test.class.getDeclaredMethod("process");
        Access[] a = m.getDeclaredAnnotationsByType(Access.class);
        System.out.println(a.length);
        Arrays.stream(a).forEach(System.out::println);
        System.out.println("------");
        Access[] a2 = m.getDeclaredAnnotationsByType(Access.class);
        System.out.println(a2.length);
        Arrays.stream(a2).forEach(System.out::println);
        System.out.println("------");
        Access a3 = m.getAnnotation(Access.class);
        System.out.println(a3);
    }

    @Target({ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    @Repeatable(MultiAccess.class)
    public @interface Access {
        String value() default "ADMIN";
    }

    @Target({ElementType.METHOD})
    @Retention(RetentionPolicy.RUNTIME)
    public @interface MultiAccess {
        Access[] value() default @Access;
    }

}

Output

2
@com.logicbig.example.method.GetDeclaredAnnotationsByTypeExample2$Access(value="SUPER_USER")
@com.logicbig.example.method.GetDeclaredAnnotationsByTypeExample2$Access(value="CUSTOMER")
------
2
@com.logicbig.example.method.GetDeclaredAnnotationsByTypeExample2$Access(value="SUPER_USER")
@com.logicbig.example.method.GetDeclaredAnnotationsByTypeExample2$Access(value="CUSTOMER")
------
null

See Also