BinaryTree.java

/*
 *  Java Program to Implement Binary Tree
 */
 
 import java.util.Scanner;
 
 /* Class BTNode */
 class BTNode
 {    
     BTNode left, right;
     int data;
 
     /* Constructor */
     public BTNode()
     {
         left = null;
         right = null;
         data = 0;
     }
     /* Constructor */
     public BTNode(int n)
     {
         left = null;
         right = null;
         data = n;
     }
     /* Function to set left node */
     public void setLeft(BTNode n)
     {
         left = n;
     }
     /* Function to set right node */ 
     public void setRight(BTNode n)
     {
         right = n;
     }
     /* Function to get left node */
     public BTNode getLeft()
     {
         return left;
     }
     /* Function to get right node */
     public BTNode getRight()
     {
         return right;
     }
     /* Function to set data to node */
     public void setData(int d)
     {
         data = d;
     }
     /* Function to get data from node */
     public int getData()
     {
         return data;
     }     
 }
 
 /* Class BT */
 class BT
 {
     private BTNode root;
 
     /* Constructor */
     public BT()
     {
         root = null;
     }
     /* Function to check if tree is empty */
     public boolean isEmpty()
     {
         return root == null;
     }
     /* Functions to insert data */
     public void insert(int data)
     {
         root = insert(root, data);
     }
     /* Function to insert data recursively */
     private BTNode insert(BTNode node, int data)
     {
         if (node == null)
             node = new BTNode(data);
         else
         {
             if (node.getRight() == null)
                 node.right = insert(node.right, data);
             else
                 node.left = insert(node.left, data);             
         }
         return node;
     }     
     /* Function to count number of nodes */
     public int countNodes()
     {
         return countNodes(root);
     }
     /* Function to count number of nodes recursively */
     private int countNodes(BTNode r)
     {
         if (r == null)
             return 0;
         else
         {
             int l = 1;
             l += countNodes(r.getLeft());
             l += countNodes(r.getRight());
             return l;
         }
     }
     /* Function to search for an element */
     public boolean search(int val)
     {
         return search(root, val);
     }
     /* Function to search for an element recursively */
     private boolean search(BTNode r, int val)
     {
         if (r.getData() == val)
             return true;
         if (r.getLeft() != null)
             if (search(r.getLeft(), val))
                 return true;
         if (r.getRight() != null)
             if (search(r.getRight(), val))
                 return true;
         return false;         
     }
     /* Function for inorder traversal */
     public void inorder()
     {
         inorder(root);
     }
     private void inorder(BTNode r)
     {
         if (r != null)
         {
             inorder(r.getLeft());
             System.out.print(r.getData() +" ");
             inorder(r.getRight());
         }
     }
     /* Function for preorder traversal */
     public void preorder()
     {
         preorder(root);
     }
     private void preorder(BTNode r)
     {
         if (r != null)
         {
             System.out.print(r.getData() +" ");
             preorder(r.getLeft());             
             preorder(r.getRight());
         }
     }
     /* Function for postorder traversal */
     public void postorder()
     {
         postorder(root);
     }
     private void postorder(BTNode r)
     {
         if (r != null)
         {
             postorder(r.getLeft());             
             postorder(r.getRight());
             System.out.print(r.getData() +" ");
         }
     }     
 }
 
 /* Class BinaryTree */
 public class BinaryTree
 {
     public static void main(String[] args)
    {            
        Scanner scan = new Scanner(System.in);
        /* Creating object of BT */
        BT bt = new BT(); 
        /*  Perform tree operations  */
        System.out.println("Binary Tree Test\n");          
        char ch;        
        do    
        {
            System.out.println("\nBinary Tree Operations\n");
            System.out.println("1. insert ");
            System.out.println("2. search");
            System.out.println("3. count nodes");
            System.out.println("4. check empty");
 
            int choice = scan.nextInt();            
            switch (choice)
            {
            case 1 : 
                System.out.println("Enter integer element to insert");
                bt.insert( scan.nextInt() );                     
                break;                          
            case 2 : 
                System.out.println("Enter integer element to search");
                System.out.println("Search result : "+ bt.search( scan.nextInt() ));
                break;                                          
            case 3 : 
                System.out.println("Nodes = "+ bt.countNodes());
                break;     
            case 4 : 
                System.out.println("Empty status = "+ bt.isEmpty());
                break;            
            default : 
                System.out.println("Wrong Entry \n ");
                break;   
            }
            /*  Display tree  */ 
            System.out.print("\nPost order : ");
            bt.postorder();
            System.out.print("\nPre order : ");
            bt.preorder();
            System.out.print("\nIn order : ");
            bt.inorder();
 
            System.out.println("\n\nDo you want to continue (Type y or n) \n");
            ch = scan.next().charAt(0);                        
        } while (ch == 'Y'|| ch == 'y');               
    }
 }