IteratorDemo.java

package collectionPrograms;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.ListIterator;

public class IteratorDemo {

	public static void main(String args[]) {
	      // Create an array list
	      ArrayList al = new ArrayList();
	      
	      // add elements to the array list
	      al.add("C");
	      al.add("A");
	      al.add("E");
	      al.add("B");
	      al.add("D");
	      al.add("F");

	      // Use iterator to display contents of al
	      System.out.print("Original contents of al: ");
	      Iterator itr = al.iterator();
	      
	      while(itr.hasNext()) {                //checking whether the next element is available
	         Object element = itr.next();		//next() returns object of that class
	         System.out.print(element + " ");
	      }
	      System.out.println();
	      
	      // Modify objects being iterated
	      ListIterator litr = al.listIterator();
	      
	      while(litr.hasNext()) {
	         Object element = litr.next();
	         litr.set(element + "+");
	      }
	      System.out.print("Modified contents of al: ");
	      itr = al.iterator();
	      
	      while(itr.hasNext()) {
	         Object element = itr.next();
	         System.out.print(element + " ");
	      }
	      System.out.println();

	      // Now, display the list backwards
	      System.out.print("Modified list backwards: ");
	      
	      while(litr.hasPrevious()) {
	         Object element = litr.previous();
	         System.out.print(element + " ");
	      }
	      System.out.println();
	   }
}