Circular Linked List Help

Question

Hi,
I'm developing a circular linked list class.. However everytime I add to the front of the list it overwrites the first element in the list.. I pretty confused at the moment. If anyone could assist me in what I'm doing wrong it would be greatly appreciated..
My Class:
public class CNode<T>
     public T nodeValue;          //data held by the node
     public CNode<T> next;     //next node in the list
     //default constructor; next references node itself
     public CNode()
          nodeValue = null;
          next = this;
     //constructor; initializes nodeValue to item
     //and sets the next to reference the node itself
     public CNode(T item)
          nodeValue = item;
          next = this;
}My addFirst:
public static <T> void addFirst(CNode<T> header, T item)
          CNode<T> curr;
          CNode<T> newNode = new CNode<T>(item);
          //header.next = newNode;
          //newNode.next = header;
          curr = header;
          newNode.next = header;
          curr.next = newNode;
     }

Answer 1

You need a Node class and a class that manages the nodes. The class the manages the nodes is typically called something like MyLinkedList. The MyLinkedList class will typically have a member called 'head' or 'first' and another member called 'last', 'end', or 'tail'. Those members will contain references to the first node and the last node respectively.
The methods like add(), remove(), find(), etc. will be members of the MyLinkedList class--not the Node class. The add() method of the MyLinkedList class will create a node, set the value of the node, and then set the next member to refer to the proper node or null if the node is added to the end of the list. Therefore, there is really no need for a default constructor in the node class. The MyLinkedList class will always set the value of the node, and then set it's next member to refer to something.
You might want to try to write a linear linked list first, and get that working, and then modify it to make it a circular linked list. In addition, you should be drawing pictures of nodes with arrows connecting the different nodes to understand what's going on. Whenver the next member of a node refers to another node, draw an arrow starting at the next member and ending at the node it refers to. The pictures will be especially helpful when you write functions like add().
Message was edited by:
7stud