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Class getAnnotation() method in Java with Examples

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  • Last Updated : 27 Dec, 2019
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The getAnnotation() method of java.lang.Class class is used to get the annotation of the specified annotation type, if such an annotation is present in this class. The method returns that class in the form of an object.

Syntax:

public T getAnnotation(Class<T> annotationClass)

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

Return Value: This method returns the specified object of the annotation class.

Exception: This method throws:

  • NullPointerException: if the given annotation class is null.

Below programs demonstrate the getAnnotation() method.

Example 1:




// Java program to demonstrate
// getAnnotation() method
  
import java.util.*;
import java.lang.annotation.*;
  
// create a custom Annotation
@Retention(RetentionPolicy.RUNTIME)
@interface Annotation {
  
    // This annotation has two attributes.
    public String key();
  
    public String value();
}
  
// call Annotation for method
// and pass values for annotation
@Annotation(key = "GFG", value = "GeeksForGeeks")
public class Test {
  
    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 annotation
        // using getAnnotation() method
        System.out.println(
            "Annotation of myClass: "
            + myClass.getAnnotation(
                  Annotation.class));
    }
}

Output:

Class represented by myClass: class Test
Annotation of myClass: @Annotation(key=GFG, value=GeeksForGeeks)

Example 2:




// Java program to demonstrate
// getAnnotation() method
  
import java.util.*;
import java.lang.annotation.*;
  
// Class with no annotations
// getAnnotation() will return null
public class Test {
  
    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 annotation
        // using getAnnotation() method
        System.out.println(
            "Annotation of myClass: "
            + myClass.getAnnotation(
                  Annotation.class));
    }
}

Output:

Class represented by myClass: class Test
Annotation of myClass: null

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


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