Why iterators should not be used ... ?

Why iterators should not be used ... ?

Iterator's compared to for and while loops ... A performance test
Iterator provides a very handy way to loop through a list or collection, but it is slower than For and While loop.

import java.util.Arrays;
import java.util.Date;
import java.util.Iterator;
import java.util.List;
 
public class ArrayToList {
  public static void main(String[] argv) {
 
   String sArray[] = createArray();
 
   //convert array to list
   List lList = Arrays.asList(sArray);
 
   System.out.println("\n--------- Iterator Loop -------\n");
   long lIteratorStartTime = new Date().getTime();
   System.out.println("Start: " + lIteratorStartTime);
 
   //iterator loop
   Iterator<String> iterator = lList.iterator();
   while ( iterator.hasNext() ){
       String stemp = iterator.next();
   }
   long lIteratorEndTime = new Date().getTime();
   System.out.println("End: " + lIteratorEndTime);
 
   long lIteratorDifference = lIteratorEndTime - lIteratorStartTime;
   System.out.println("Iterator - Elapsed time in milliseconds: " + lIteratorDifference);
 
   System.out.println("\n-------END-------");
 
 
 
   System.out.println("\n--------- For Loop --------\n");
   long lForStartTime = new Date().getTime();
   System.out.println("Start: " + lForStartTime);
 
   //for loop
   for (int i=0; i< lList.size(); i++){
    String stemp = (String)lList.get(i);
   }
 
   long lForEndTime = new Date().getTime();
   System.out.println("End: " + lForEndTime);
 
   long lForDifference = lForEndTime - lForStartTime;
   System.out.println("For - Elapsed time in milliseconds: " + lForDifference);
 
   System.out.println("\n-------END-------");
 
 
   System.out.println("\n--------- While Loop -------\n");
   long lWhileStartTime = new Date().getTime();
   System.out.println("Start: " + lWhileStartTime);
 
   //while loop
   int j=0; 
   while (j< lList.size())
   {
    String stemp = (String)lList.get(j);
    j++;
   }
   long lWhileEndTime = new Date().getTime();
   System.out.println("End: " + lWhileEndTime);
 
   long lWhileDifference = lWhileEndTime - lWhileStartTime;
   System.out.println("While - Elapsed time in milliseconds: " + lWhileDifference);
 
   System.out.println("\n-------END-------");
 
 
  }
 
  static String [] createArray(){
 
   String sArray[] = new String [15000000];
 
   for(int i=0; i<15000000; i++)
    sArray[i] = "Array " + i;
 
   return sArray;
  }
}

output :  

D:\test>java -Xms1024m -Xmx1024m ArrayToList
 
 
--------- Iterator Loop -------
 
Start: 1232435614372
End: 1232435614763
Iterator - Elapsed time in milliseconds: 390
 
-------END-------
 
--------- For Loop --------
 
Start: 1232435614763
End: 1232435614997
For - Elapsed time in milliseconds: 234
 
-------END-------
 
--------- While Loop -------
 
Start: 1232435614997
End: 1232435615232
While - Elapsed time in milliseconds: 234
 
-------END-------