// File: GenericList.java
//
// Author: Rahul Simha
// Created: Sept 21, 1998
//
// The Generic list code, all by itself.


// A node that contains any "Object"

class ListItem {

    Object data = null;    // The universal Object.
    ListItem next = null;
    
    // Constructor.
    public ListItem (Object obj)
    {
	data = obj;  next = null;
    }
    
    // Accessor.
    public Object getData () 
    {
	return data;
    }
}


// Linked list class - also a dynamic class.

public class GenericList {

    ListItem front = null;
    ListItem rear = null;
    int numItems = 0;      // Current number of items.
    
    // Instance method to add a data item.
    public void addData (Object obj)
    {
	if (front == null) {
	    front = new ListItem (obj);
	    rear = front;
	}
	else {
	    rear.next = new ListItem (obj);
	    rear = rear.next;
	}
	numItems++;
    }

    public void printList ()
    {
	ListItem listPtr = front;
	System.out.println ("List: (" + numItems + " items)");
	int i = 1;
	while (listPtr != null) {
	    System.out.println ("Item# " + i + ": " 
				+ listPtr.getData());
                               // Must implement toString()
	    i++;
	    listPtr = listPtr.next;
	}
    }

    ListItem enumPtr = null;
    
    // Start an enumeration.
    public void startEnumeration ()
    {
	enumPtr = front;
    }
    
    public boolean hasMoreElements()
    {
	if (enumPtr == null)
	    return false;
	else
	    return true;
    }
    
    public Object getNextElement()
    {
	Object obj = enumPtr.data;
	enumPtr = enumPtr.next;
	return obj;
    }
    
} // End of class "LinkedList"