Class getDeclaredAnnotationsByType() method in Java with Examples

The getDeclaredAnnotationsByType() method of java.lang.Class class is used to get the declared annotations of the specified declared annotation type present in this class. The method returns an array of declared annotations for the specified declared annotation type.

Syntax:

public A[] getDeclaredAnnotationsByType(Class<T> declared annotationClass)

Parameter: This method accepts a parameter declared annotationClass which is the type of the declared annotation to get.

Return Value: This method returns an array of declared annotations for the specified declared annotation type.

Exception: This method throws:

• NullPointerException: if the given declared annotation class is null.

Below programs demonstrate the getDeclaredAnnotationsByType() method.

Example 1:

// Java program to demonstrate
// getDeclaredAnnotationsByType() method

import java.util.*;
import java.lang.annotation.*;

// create a custom DeclaredAnnotation
@Retention(RetentionPolicy.RUNTIME)
@interface DeclaredAnnotation {

    // This declared annotation has two attributes.
    public String key();

    public String value();
}

// call DeclaredAnnotation for method
// and pass values for declared annotation
@DeclaredAnnotation(key = "GFG", value = "GeeksForGeeks")
public class Test {

    public Object obj;

    public static void main(String[] args)
        throws ClassNotFoundException
    {

        // returns the Class object for this class
        Class myClass = Test.class;

        System.out.println(
            "Class represented by myClass: "
            + myClass.toString());

        // Get the declared annotation
        // using getDeclaredAnnotationsByType() method
        System.out.println(
            "DeclaredAnnotation of myClass of type DeclaredAnnotation: "
            + Arrays.toString(
                  myClass
                      .getDeclaredAnnotationsByType(
                          DeclaredAnnotation.class)));
    }
}

Output:

Class represented by myClass: class Test
DeclaredAnnotation of myClass of type DeclaredAnnotation: [@DeclaredAnnotation(key=GFG, value=GeeksForGeeks)]

Example 2:

// Java program to demonstrate
// getDeclaredAnnotationsByType() method

import java.util.*;
import java.lang.annotation.*;

@Deprecated
public class Test {

    public Object obj;

    public static void main(String[] args)
        throws ClassNotFoundException
    {
        try {
            // returns the Class object for this class
            Class myClass = Test.class;

            System.out.println(
                "Class represented by myClass: "
                + myClass.toString());

            // Get the declared annotation
            // using getDeclaredAnnotationsByType() method
            System.out.println(
                "DeclaredAnnotation of myClass of type Deprecated: "
                + Arrays.toString(
                      myClass
                          .getDeclaredAnnotationsByType(
                              Deprecated.class)));
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

Class represented by myClass: class Test
DeclaredAnnotation of myClass of type Deprecated: [@java.lang.Deprecated()]

Reference: https://docs.oracle.com/javase/9/docs/api/java/lang/Class.html#getDeclaredAnnotationsByType-java.lang.Class-