BTNode.java

/** Node of a binary tree with labels of type E */

public class BTNode<E> {
   private E element;
   private BTNode<E> left, right, parent;

   /** default constructor */
   public BTNode() { }

   /** constructor with parameters */
   public BTNode(E e, BTNode u, BTNode v, BTNode w) {
      setElement(e);
      setParent(u);
      setLeft(v);
      setRight(w);
   }
    /** accessor methods: */
    
   public E element() { return element; }
    
   public void setElement(E e) { element=e; }
    
   public BTNode<E> leftChild() { return left; }
    
   public void setLeft(BTNode<E> v) { left=v; }
    
   public BTNode<E> rightChild() { return right; }
    
   public void setRight(BTNode<E> v) { right=v; }
    
   public BTNode<E> parent() { return parent; }
    
   public void setParent(BTNode<E> v) { parent=v; }

    /** methods for  checking basic properties: */
    
   public boolean isLeaf() {
      return ( left==null && right==null);
   }
   public boolean isInternal() {
      return ( left!=null || right!=null);
   }
      /** note that in proper binary trees one could use && instead of || */
    
   public boolean isRoot() { return (parent==null); }

}