// Written by:  Darren Gates & Ray Klefstad
// Date:        January 2000
// School:      U.C. Irvine

import java.util.*;
import java.awt.*;
import java.applet.*;

public class EnumerationExample
    extends Applet
{
    private TextArea display;
    
    public void init()
    {
        display = new TextArea(8, 35);
        add(display);
        String result = "";
        
        SomeList myList = new SomeList();
        myList.insert("list.");
        myList.insert("my");
        myList.insert("is");
        myList.insert("This");
		
	Enumeration e = myList.elements();
        result = "Now enumerating through the list... \n\n";
        
        while (e.hasMoreElements())
	{
		result += "Next element is: " + e.nextElement() + "\n";
	}
        
        display.setText(result);
    }
}

class SomeList implements Enumeration
{
	public static class Node
	{
		private Object info;
		private Node next;
        
		public Node(Object newInfo, Node newNext)
		{
			info = newInfo;
			next = newNext;
		}
	}
    
	private Node head;
    
	public SomeList()
	{
		head = null;
	}
    
	public void insert(Object info)
	{
		head = new Node(info, head);
	}
    
	private Node cur;
	
	public Enumeration elements()
	{
		cur = head;
		return this;
	}
	
/* the methods to implement Enumeration */

	public boolean hasMoreElements()
	{
		return cur == null ? false : true;
	}
	
	public Object nextElement()
	{
		Node result = cur;
		cur = cur.next;
		return result.info;
	}
}