BinNode

public class BinNode {
		
	public int value;
	public int depth;
	public BinNode left;
	public BinNode right;
	
	public BinNode(int value, BinNode left, BinNode right){
		this.value = value;
		this.left = left;
		this.right = right;
	}
}

LevelOrderTreePrint

import java.util.Deque;
import java.util.LinkedList;

public class LevelOrderTreePrint {

	public static void main(String[] args) {

		// binary test
		BinNode bn4 = new BinNode(7, null, null);
		BinNode bn3 = new BinNode(15, null, null);
		BinNode bn2 = new BinNode(20, bn3, bn4);
		BinNode bn1 = new BinNode(9, null, null);
		BinNode root = new BinNode(3, bn1, bn2);

		printBinaryTree(root);
		
		System.out.println();
		
		// K-ary test
		Node n4 = new Node(7);
		Node n3 = new Node(15);
		Node n2 = new Node(20);
		n2.children.add(n3);
		n2.children.add(n4);
		Node n1 = new Node(9);
		Node root2 = new Node(3);
		root2.children.add(n1);
		root2.children.add(n2);
		
		printKaryTree(root2);
		
	}

	private static void printBinaryTree(BinNode root) {

		root.depth = 0;
		Deque<BinNode> queue = new LinkedList<BinNode>();
		queue.add(root);

		int depth = 0;

		while (!queue.isEmpty()) {

			BinNode curr = queue.poll();

			if (curr.depth > depth) {
				System.out.println();
				depth = curr.depth;
			}

			System.out.print(curr.value + " ");

			if (curr.left != null) {
				curr.left.depth = depth + 1;
				queue.add(curr.left);
			}
			if (curr.right != null) {
				curr.right.depth = depth + 1;
				queue.add(curr.right);
			}
		}

	}

	private static void printKaryTree(Node root) {

		root.depth = 0;
		Deque<Node> queue = new LinkedList<Node>();
		queue.add(root);

		int depth = 0;

		while (!queue.isEmpty()) {
			
			Node curr = queue.poll();

			if (curr.depth > depth) {
				System.out.println();
				depth = curr.depth;
			}
			System.out.print(curr.value + " ");

			for (Node child : curr.children) {
				child.depth = depth + 1;
				queue.add(child);
			}
		}
	}

}

Node

import java.util.ArrayList;
import java.util.List;

public class Node {

	public int value;
	public int depth;
	public List<Node> children;
	
	public Node(int value){
		this.value = value;
		this.children = new ArrayList<Node>();
	}
}