print level wise nodes in the binary tree (Breadth First Traversal)

This can be achieved using breadth first traversal algorithm.
– push level wise nodes into the queue at every iteration
– pop the node from queue at every iteration and print its value

Lets look at example:

            20
    15              25
12      18      22      28

BFS puts this tree in queue such there level wise nodes are placed one-another like this

	--------------------------------
	20 | 15 | 25 | 12 | 18 | 22 | 28
	--------------------------------

And at every loop element from queue is removed in FIFO manner

	public void breadthFirstNonRecursive() {
		Queue<BinaryNode> queue = new java.util.LinkedList<BinaryNode>();
		queue.offer(root);
		while (!queue.isEmpty()) {
			BinaryNode node = queue.poll();
			System.out.println(node.element);
			if (node.left != null)
				queue.offer(node.left);
			if (node.right != null)
				queue.offer(node.right);
		}
	}

Output: 20, 15, 25, 12, 18, 22, 28