Java.lang.Class.asSubclass() Method

Description

The java.lang.Class.asSubclass() method casts this Class object to represent a subclass of the class represented by the specified class object.It is useful when a client needs to "narrow" the type of a Class object to pass it to an API that restricts the Class objects that it is willing to accept.

Declaration

Following is the declaration for java.lang.Class.asSubclass() method

public <U> Class<? extends U> asSubclass(Class<U> clazz)

Parameters

• NA

Return Value

This method returns this Class object, cast to represent a subclass of the specified class object.

Exception

• ClassCastException -- if this Class object does not represent a subclass of the specified class (in this "subclass" includes the class itself).

Example

The following example shows the usage of java.lang.Class.asSubclass() method.

package com.tutorialspoint;

import java.lang.*;

public class ClassDemo {

   public static void main(String[] args) {

     try {
        ClassDemo cls = new ClassDemo();
        ClassDemo subcls = new SubClass1(); 
 
        // class ClassDemo
        Class c = cls.getClass(); 
        System.out.println(c);
 
        // sub class SubClass1
        Class c1 = subcls.getClass();
        System.out.println(c1);
    
        // represent a subclass of the specified class object
        Class retval = c1.asSubclass(c);
   
        System.out.println(retval);
     }
   
     catch(ClassCastException e) {
        System.out.println(e.toString());
     }
   }
}
   
class SubClass1 extends ClassDemo {
    // sub class
} 

Let us compile and run the above program, this will produce the following result:

class ClassDemo
class SubClass1
class SubClass1