Package isAnnotationPresent() method in Java with Examples

The isAnnotationPresent() method of java.lang.Package class is used to check if an annotation of the specified annotation type is present in this class. The method returns a boolean value stating the same.

Syntax:

public boolean isAnnotationPresent(Class<T> annotationClass)

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



Return Value: This method returns boolean value stating the same.

Exception: This method throws:

  • NullPointerException: if the given annotation class is null.

Below programs demonstrate the isAnnotationPresent() method.

Example 1:

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// Java program to demonstrate
// isAnnotationPresent() 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());
  
        // Check if there is any annotation
        // using isAnnotationPresent() method
        System.out.println(
            "If there is any annotation in myClass: "
            + myClass.isAnnotationPresent(
                  Annotation.class));
    }
}

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Output:

Class represented by myClass: class Test
If there is any annotation in myClass: true

Example 2:

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// Java program to demonstrate
// isAnnotationPresent() method
  
import java.util.*;
import java.lang.annotation.*;
  
// Class with no annotations
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 isAnnotationPresent() method
        System.out.println(
            "If there is any annotation in myClass: "
            + myClass.isAnnotationPresent(
                  Annotation.class));
    }
}

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Output:

Class represented by myClass: class Test
If there is any annotation in myClass: false

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



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