/* ListNode.java 1.0                                      */
/* originally from Georgia Tech's CS 1322 Module 27 notes */
/*    on Linked Lists, Stacks, and Queues                 */
/* modified/adapted by Sharon Tuttle                      */
/* last modified: 2-27-03                                 */

public class ListNode implements Comparable
{
    /*------------------------------------
     fields
    -------------------------------------*/
    
    // information we want to be in a linked list
    private Comparable data;     // data must be of type Comparable ---
					             // it must be of a class that either
					             // implements Comparable, or it is a
					             // subclass of a class that does so.
    
    // next node in the linked list
    private ListNode next;

    /*--------------------------------------
     constructors
    ---------------------------------------*/

    /* create a new node containing the desired data  */
    /* but not leading to any other node              */
    public ListNode (Comparable desiredData)
    {
        this.data = desiredData;
        this.next = null;
    }    

    /*-------------------------------------------------------
     accessors
    -------------------------------------------------------*/ 

    public Comparable getData()
    {
        return this.data;
    }

    public ListNode getNext()
    {
        return this.next;
    }

    /*-------------------------------------------------------
     modifiers
    -------------------------------------------------------*/ 

    public void setData(Comparable newData)
    {
        this.data = newData;
    }

    public void setNext(ListNode newNext)
    {
        this.next = newNext;
    }

    /*-----------------------------------------------------------
     implementations of interface's abstract methods
    --------------------------------------------------------------*/
  
    public int compareTo(Object obj)
    {
        // yes, this is clunky. compareTo() must conform to the
        // given interface, but I cannot really compare it unless
        // it is a ListNode object. So, I cast the parameter object 
        // to that type, which should work because I only plan to
        // call this for ListNode objects comparing themselves to
        // OTHER ListNode objects...

        ListNode objNode = (ListNode) obj;

        // get the data from the passed (assumed) ListNode
        Comparable objData = objNode.getData();

        // data must be of type Comparable --- so I know it, too, supports
        // method compareTo()...
        return ( (this.data).compareTo(objData) );
    }

    /*------------------------------------------
     overridden methods
    -------------------------------------------*/
    public String toString()
    {
        /* hmm; I don't think I'll print next in list... */
        return "ListNode[" + this.data + "]";
    }
    
} // end of class ListNode