ClassDemo.java

The java.lang.Class.cast() method casts an object to the class or interface represented by this Class object.

This method returns the object after casting, or null if obj is null.

Exception ClassCastException is thrown if the object is not null and is not assignable to the specified type.

The example program produced the following when run from the command window: 

C:\work>java ClassDemo
class ClassDemo
Class B show() function
Whoops Cannot cast A to B
obj is class A
b1 is class B
a1 is class B

ClassDemo.java

import java.lang.*;

class A {
   public static void show() {
      System.out.println("Class A show() function");
   }
}

class B extends A {
   public static void show() {
      System.out.println("Class B show() function");
   }
}

public class ClassDemo {

   public static void main(String[] args) {

      ClassDemo cls = new ClassDemo();
      Class c = cls.getClass();      
      System.out.println(c);  

      Object obj = new A();        
      B b1 = new B();
      b1.show();

      // casts object
      Object a1 = A.class.cast(b1);
      try {
	B b2 = B.class.cast(obj);
      }
      catch(ClassCastException e) {
	System.out.println("Whoops " + e.getMessage());
      }

      System.out.println("obj is " + obj.getClass());
      System.out.println("b1 is " + b1.getClass());
      System.out.println("a1 is " + a1.getClass());               
   }
}

Maintained by John Loomis, updated Thu Mar 22 15:02:21 2018