ListNode.java

/**
 * Class: ListNode
 * Author: Chang LIU
 */

package linkedlist;

import static java.lang.System.out;

public class ListNode<T> {

  /* Dummy data payload */
  private static final Object DUMMY = new Object();

  private ListNode<T> next = null;
  private T data = null;

  public ListNode() { }

  public ListNode(T data) {
    this.data = data;
  }

  /*
   * Add a new node after the current node
   * Time Complexity: O(1)
   */
  public void add(T data) {
    ListNode<T> newNode = new ListNode<T>(data);
    newNode.next = this.next;
    this.next = newNode;
  }

  /*
   * Delete the next node of current node
   * Time Complexity: O(1)
   */
  public T delete() throws DummyNodeException {
    if (isDummy()) { /* The current node is the last node. */
      throw new DummyNodeException("This is a dummy node.");
    }

    if (this.next != null) {
      ListNode<T> nextNode = this.next;
      T thisData = this.data;
      this.data = nextNode.data;
      this.next = nextNode.next;
      return thisData;
    } else {
      throw new UnsupportedOperationException("Next is null.");
    }
  }

  /*
   * Check whether this node is dummy node
   */
  public boolean isDummy() {
    return data == DUMMY;
  }

  /*
   * Check whether this node is dummy node
   */
  @SuppressWarnings("unchecked")
  public void setDummy() {
    data = (T)DUMMY;
  }

  /* getters, setters and toString() */

}