Binary Tree in Java

Implementation of Binary Tree in Java Language.

import java.io.*;
import java.util.*; 

class Node
   {
   public int iData;              // data item (key)
   public double dData;           // data item
      public Node leftChild;         // this node's left child
   public Node rightChild;        // this node's right child

   public void displayNode()      // display ourself
      {
      System.out.print('{');
      System.out.print(iData);
      System.out.print(", ");
      System.out.print(dData);
      System.out.print("} ");
      }
   }  // end class Node

class Tree
   {
   private Node root;             // first node of tree


   public Tree()                  // constructor
      { root = null; }            // no nodes in tree yet
// ------------------ Find A Node -------------------------------------------
   public Node find(int key)      // find node with given key
      {                           // (assumes non-empty tree)
      Node current = root;               // start at root
      while(current.iData != key)        // while no match,
         {
         if(key < current.iData)         // go left?
            current = current.leftChild;
         else                            // or go right?
            current = current.rightChild;
         if(current == null)             // if no child,
            return null;                 // didn't find it
         }
      return current;                    // found it
      }  // end find()
// ------------------- Insert A Node ------------------------------------------
   public void insert(int id, double dd)
      {
      Node newNode = new Node();    // make new node
      newNode.iData = id;           // insert data
      newNode.dData = dd;
      if(root==null)                // no node in root
         root = newNode;
      else                          // root occupied
         {
         Node current = root;       // start at root
         Node parent;
         while(true)                // (exits internally)
            {
            parent = current;
            if(id < current.iData)  // go left?
               {
               current = current.leftChild;
               if(current == null)  // if end of the line,
                  {                 // insert on left
                  parent.leftChild = newNode;
                  return;
                  }
               }  // end if go left
            else                    // or go right?
               {
               current = current.rightChild;
               if(current == null)  // if end of the line
                  {                 // insert on right
                  parent.rightChild = newNode;
                  return;
                  }
               }  // end else go right
            }  // end while
         }  // end else not root
      }  // end insert()
// ----------------------- Delete A Node --------------------------------------
   public boolean delete(int key) // delete node with given key
      {                           // (assumes non-empty list)
      Node current = root;
      Node parent = root;
      boolean isLeftChild = true;

      while(current.iData != key)        // search for node
         {
         parent = current;
         if(key < current.iData)         // go left?
            {
            isLeftChild = true;
            current = current.leftChild;
            }
         else                            // or go right?
            {
            isLeftChild = false;
            current = current.rightChild;
            }
         if(current == null)             // end of the line,
            return false;                // didn't find it
         }  // end while
      // found node to delete

      // if no children, simply delete it
      if(current.leftChild==null &&
                                   current.rightChild==null)
         {
         if(current == root)             // if root,
            root = null;                 // tree is empty
         else if(isLeftChild)
            parent.leftChild = null;     // disconnect
         else                            // from parent
            parent.rightChild = null;
         }

      // if no right child, replace with left subtree
      else if(current.rightChild==null)
         if(current == root)
            root = current.leftChild;
         else if(isLeftChild)
            parent.leftChild = current.leftChild;
         else
            parent.rightChild = current.leftChild;

      // if no left child, replace with right subtree
      else if(current.leftChild==null)
         if(current == root)
            root = current.rightChild;
         else if(isLeftChild)
            parent.leftChild = current.rightChild;
         else
            parent.rightChild = current.rightChild;

      else  // two children, so replace with inorder successor
         {
         // get successor of node to delete (current)
         Node successor = getSuccessor(current);

         // connect parent of current to successor instead
         if(current == root)
            root = successor;
         else if(isLeftChild)
            parent.leftChild = successor;
         else
            parent.rightChild = successor;

         // connect successor to current's left child
         successor.leftChild = current.leftChild;
         }  // end else two children
      // (successor cannot have a left child)
      return true;                                // success
      }  // end delete()

// --------------------- Traverse Tree ----------------------------------------
   public void traverse(int traverseType)
      {
      switch(traverseType)
         {
         case 1: System.out.print("\nPreorder traversal: ");
                 preOrder(root);
                 break;
         case 2: System.out.print("\nInorder traversal:  ");
                 inOrder(root);
                 break;
         case 3: System.out.print("\nPostorder traversal: ");
                 postOrder(root);
                 break;
         }
      System.out.println();
      }
// ----------------------- Pre Order Traversal --------------------------------------
   private void preOrder(Node localRoot)
      {
      if(localRoot != null)
         {
         System.out.print(localRoot.iData + " ");
         preOrder(localRoot.leftChild);
         preOrder(localRoot.rightChild);
         }
      }
// ----------------------- In Order Traversal ------------------------------------
   private void inOrder(Node localRoot)
      {
      if(localRoot != null)
         {
         inOrder(localRoot.leftChild);
         System.out.print(localRoot.iData + " ");
         inOrder(localRoot.rightChild);
         }
      }
// ---------------------- Post Order Traversal ---------------------------------------
   private void postOrder(Node localRoot)
      {
      if(localRoot != null)
         {
         postOrder(localRoot.leftChild);
         postOrder(localRoot.rightChild);
         System.out.print(localRoot.iData + " ");
         }
      }
// ----------------------- Disply/Print Tree --------------------------------------
   public void displayTree()
      {
      Stack globalStack = new Stack();
      globalStack.push(root);
      int nBlanks = 32;
      boolean isRowEmpty = false;
      System.out.println(
      "......................................................");
      while(isRowEmpty==false)
         {
         Stack localStack = new Stack();
         isRowEmpty = true;

         for(int j=0; j