Triple order traversal of a binary tree in java

Java program for Triple order traversal of a binary tree. Here more solutions.

/*
    Java program for
    Triple order traversal of a binary tree
*/
// Binary Tree node
class TreeNode
{
    public int data;
    public TreeNode left;
    public TreeNode right;
    public TreeNode(int data)
    {
        // Set node value
        this.data = data;
        this.left = null;
        this.right = null;
    }
}
public class BinaryTree
{
    public TreeNode root;
    public BinaryTree()
    {
        // Set initial tree root
        this.root = null;
    }
    public void tripleOrder(TreeNode node)
    {
        if (node != null)
        {
            // Print preorder node 
            System.out.print(" " + node.data);
            // Visit left subtree
            this.tripleOrder(node.left);
            // Print inorder node  
            System.out.print(" " + node.data);
            // Visit right subtree
            this.tripleOrder(node.right);
            // Print postorder node
            System.out.print(" " + node.data);
        }
    }
    public static void main(String[] args)
    {
        // Create new binary trees 
        BinaryTree tree = new BinaryTree();
        /*
                 4    
                / \                         
               /   \    
             -4     7    
             / \     \               
            2   3     1
               / \   / 
              6   8 5
             /       
            9          
          ----------------------
          Constructing binary tree
        */
        tree.root = new TreeNode(4);
        tree.root.left = new TreeNode(-4);
        tree.root.left.right = new TreeNode(3);
        tree.root.left.right.left = new TreeNode(6);
        tree.root.left.right.left.left = new TreeNode(9);
        tree.root.left.right.right = new TreeNode(8);
        tree.root.left.left = new TreeNode(2);
        tree.root.right = new TreeNode(7);
        tree.root.right.right = new TreeNode(1);
        tree.root.right.right.left = new TreeNode(5);
        // Print triple order
      	// ----------------------------------
      	// 4 -4 2 2 2 -4 3 6 9 9 9 6 6 3 8 8 ..
        // 8 3 -4 4 7 7 1 5 5 5 1 1 7 4
        tree.tripleOrder(tree.root);
    }
}

Output

 4 -4 2 2 2 -4 3 6 9 9 9 6 6 3 8 8 8 3 -4 4 7 7 1 5 5 5 1 1 7 4