BTNode

//*******************************************************************
//  BTNode.java       Java Foundations
//
//  Represents a node in a binary tree with a left and right child.
//  Therefore this class also represents the root of a subtree.
//*******************************************************************

package javafoundations;

public class BTNode<T>
{
   protected T element;
   protected BTNode<T> left, right;

   //-----------------------------------------------------------------
   //  Creates a new tree node with the specified data.
   //-----------------------------------------------------------------
   public BTNode (T element)
   {
      this.element = element;
      left = right = null;
   }

   //-----------------------------------------------------------------
   //  Returns the element stored in this node.
   //-----------------------------------------------------------------
   public T getElement()
   {
      return element;
   }

   //-----------------------------------------------------------------
   //  Sets the element stored in this node.
   //-----------------------------------------------------------------
   public void setElement (T element)
   {
      this.element = element;
   }

   //-----------------------------------------------------------------
   //  Returns the left subtree of this node.
   //-----------------------------------------------------------------
   public BTNode<T> getLeft()
   {
      return left;
   }

   //-----------------------------------------------------------------
   //  Sets the left child of this node.
   //-----------------------------------------------------------------
   public void setLeft (BTNode<T> left)
   {
      this.left = left;
   }

   //-----------------------------------------------------------------
   //  Returns the right subtree of this node.
   //-----------------------------------------------------------------
   public BTNode<T> getRight()
   {
      return right;
   }

   //-----------------------------------------------------------------
   //  Sets the right child of this node.
   //-----------------------------------------------------------------
   public void setRight (BTNode<T> right)
   {
      this.right = right;
   }

   //-----------------------------------------------------------------
   //  Returns the element in this subtree that matches the
   //  specified target. Returns null if the target is not found.
   //-----------------------------------------------------------------
   public BTNode<T> find (T target)
   {
      BTNode<T> result = null;

      if (element.equals(target))
         result = this;
      else
      {
         if (left != null)
            result = left.find(target);
         if (result == null && right != null)
            result = right.find(target);
      }

      return result;
   }

   //-----------------------------------------------------------------
   //  Returns the number of nodes in this subtree.
   //-----------------------------------------------------------------
   public int count()
   {
      int result = 1;

      if (left != null)
         result += left.count();

      if (right != null)
         result += right.count();

      return result;
   }

   //-----------------------------------------------------------------
   //  Performs an inorder traversal on this subtree, updating the
   //  specified iterator.
   //-----------------------------------------------------------------
   public void inorder (ArrayIterator<T> iter)
   {
      if (left != null)
         left.inorder (iter);

      iter.add (element);

      if (right != null)
         right.inorder (iter);
   }

   //-----------------------------------------------------------------
   //  The following methods are left as programming projects.
   //-----------------------------------------------------------------
   // public void preorder (ArrayIterator<T> iter) { }
   // public void postorder (ArrayIterator<T> iter) { }
}