• September 6, 2014
  • Generics
  • Comments Off on ClassCastException at runtime test

ClassCastException at runtime test

Let us see the ClassCastException at runtime test in generics with the below example.

ClassCastException at run time test example:

GenericsTest.java

import java.util.ArrayList;
import java.util.List;
 
/**
 * This class is used to show the 
 * ClassCastException at runtime test.
 * @author javawithease
 */
public class GenericsTest {
	public static void main(String args[]){
		//Arraylist without generics.
		List list1 = new ArrayList();
		list1.add("Roxy");
		list1.add("Sandy");
		list1.add(new Integer(6));
		try{
			//Retrieve and print list elements.
			for(Object obj : list1){
				//ClassCastException at runtime when 
				//try to cast an integer to string.
		                String str=(String) obj;
		                System.out.println(str);
			}
		}catch(ClassCastException e){
			System.out.println();
			System.out.println();
			e.printStackTrace();
		}
 
 
		//Arraylist with generics.	
		List list2 = new ArrayList();
		list2.add("Roxy");
		list2.add("Sandy");
		list2.add("Sunil");
 
		//Retrieve and print list elements.
		for(String str : list2){
			//No ClassCastException at runtime 
			//because casting is not required.
	                System.out.println(str);
		}
 
	}
}

Output:

Roxy
Sandy
java.lang.ClassCastException: 
java.lang.Integer cannot be cast to java.lang.String
Roxy
Sandy
Sunil
at com.javawithease.business.GenericsTest.main
(GenericsTest.java:23)

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