Iterator vs Enumeration

	Enumeration	Iterator
JDK	JDK1.0 in java.lang package	JDK 1.2 in java.util package
Remove elements	Not allowed	remove() method do this for us.
Read-only	Yes	No
Thread-safe		More secure and safe because it does not allow other thread to modify the collection object while some thread is iterating over it and throws ConcurrentModificationException.
Methods	hasMoreElement() nextElement() Read-only interface.	hasNext() next() remove()

EnumIteration.java

import java.util.*;

public class EnumIteration {

       public static void main(String[] args){

              Vector v=new Vector();

              Object element;

              Enumeration enm;

              Iterator iter;

              long start;

              for(int i=0; i<1000000; i++){

                     v.add("New Element");

              }

              enm=v.elements();

              iter=v.iterator();

              //CODE BLOCK FOR ITERATOR

              start=System.currentTimeMillis();

              while(iter.hasNext()){

                     element=iter.next();

              }

              System.out.println("Iterator took"+

                               (System.currentTimeMillis()-start));

              //END OF ITERATOR BLOCK

              //request to GC to free up some memory

              System.gc();

              //CODE BLOCK FOR ENUMERATION

              start=System.currentTimeMillis();

              while(enm.hasMoreElements()){

                     element=enm.nextElement();

              }

              System.out.println("Enumeration took"+

                                (System.currentTimeMillis()-start));

              //END OF ENUMERATION BLOCK

       }

}