Find parent of every leaf nodes in binary tree in java

Java program for Find parent of every leaf nodes in binary tree. Here mentioned other language solution.

/*
    Java program for
    Find parent of leaf nodes in 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 to null
		this.root = null;
	}
	//  Find the parent of leaf nodes using recursion
	public void leafParent(TreeNode node, TreeNode parent)
	{
		if (node != null)
		{
			// Check that node is leaf node or not
			if ((node.left == null && node.right == null))
			{
				if (parent == null)
				{
					// When one node of tree
					System.out.println(" NULL");
				}
				else
				{
					System.out.print("  " + parent.data);
				}
			}
			else
			{
				// Visit left subtree
				leafParent(node.left, node);
				// Visit right subtree
				leafParent(node.right, node);
			}
		}
	}
	public static void main(String[] args)
	{
		// Create new binary trees 
		BinaryTree tree = new BinaryTree();
		/*
		         34 
		        / \                           
		       /   \    
		     -4     10    
		     / \     \               
		    7   12    6
		   /   / \     
		  4   6   8   
		     / \      
		    9   1       
		-----------------
		  Constructing binary tree
		*/
		tree.root = new TreeNode(34);
		tree.root.left = new TreeNode(-4);
		tree.root.left.right = new TreeNode(12);
		tree.root.left.right.left = new TreeNode(6);
		tree.root.left.right.left.left = new TreeNode(9);
		tree.root.left.right.left.right = new TreeNode(1);
		tree.root.left.right.right = new TreeNode(8);
		tree.root.left.left = new TreeNode(7);
		tree.root.left.left.left = new TreeNode(4);
		tree.root.right = new TreeNode(10);
		tree.root.right.right = new TreeNode(6);
		// Test
		tree.leafParent(tree.root, null);
	}
}

Output

  7  6  6  12  10