Comparison of primitive type vs Wrapper object

After coming across this question in several interviews, came up with a small piece of code to compare primitive type and wrapper object.  Auto boxing after Java 5 has shadowed the behind seen happenings to fellow developers. :-)

There will be n number of pages in google to give the differences, I am just giving a small program to compare the performance of int and Integer.

import java.util.Date;

/**

 * PerformanceTester.java

 *

 * @author cananth

 */

public class PerformanceTester {

   public void processWithWrapper() {

      long startTime = new Date().getTime();

      Integer ctr = 0;

      for (int i = 0; i < Integer.MAX_VALUE; i++) {

         ctr += i;

      }

      long endtime = new Date().getTime();

      System.out.println("---------------------------------------------------");

      System.out.println("Time using Integer: " + (endtime - startTime) + " ms");

      System.out.println("---------------------------------------------------");

   }

   public void processWithPrimitive() {

       long startTime = new Date().getTime();

       int i = 0;

       int ctr = 0;

       for (i = 0; i < Integer.MAX_VALUE; i++) {

           ctr += i;

       }

       long endtime = new Date().getTime();

       System.out.println("Time using int: " + (endtime - startTime) + " ms");

       System.out.println("---------------------------------------------------");

   }

   public static void main(String[] args) {

       System.out.println("Same Object");

       System.out.println("---------------------------------------------------");

       PerformanceTester test = new PerformanceTester();

       test.processWithWrapper();

       test.processWithPrimitive();

       test.processWithWrapper();

       test.processWithPrimitive();

             

       System.out.println();

       System.out.println("New Object");

       System.out.println("---------------------------------------------------");

       new PerformanceTester().processWithWrapper();

       new PerformanceTester().processWithPrimitive();

       new PerformanceTester().processWithWrapper();

       new PerformanceTester().processWithPrimitive();

   }

}

Output:

Same Object

---------------------------------------------------

Time using Integer: 7835 ms

---------------------------------------------------

Time using int: 1505 ms

---------------------------------------------------

Time using Integer: 7685 ms

---------------------------------------------------

Time using int: 1489 ms

---------------------------------------------------

New Object

---------------------------------------------------

Time using Integer: 7369 ms

---------------------------------------------------

Time using int: 1 ms

---------------------------------------------------

Time using Integer: 7356 ms

---------------------------------------------------

Time using int: 1 ms

---------------------------------------------------

The difference in execution is huge.  In few of my trials I have got 0ms too for the int.

Verdict: Never use wrapper class for computations.