// printLevelOrder (tree)
// Create an queue and push root node into it
// when queue is not empty
//     pop a node from the queue and print it
//     push left child of popped node to queue if not null
//     push right child of popped node to queue if not null
//                 40
//                /  \
//               20  60
//              / \  / \
//             10 30 50 70

public class BinaryTree {

public static class TreeNode {
    int data;
    TreeNode left;
    TreeNode right;
    TreeNode (int data) {
        this.data = data;
    }


}

void printLevelOrder (TreeNode rootNode) {

    Queue<TreeNode> queue = new LinkedList()<TreeNode>;
    if (rootNode != null )
        queue.add(rootNode);
    else
        return;

    while (!queue.isEmpty()) {
        TreeNode tempNode = queue.poll();
        System.out.printf("%d", tempNode.data);
        if (tempNode.left != null ) {
            queue.add(tempNode.left);
        if (tempNode.right != null ) {
            queue.add(tempNode.right);
        }
    }

}

public static void main(String args[]) }
    BinaryTree bTree = new BinaryTree();

    TreeNode rootNode = createBinaryTree();
    System.out.println("Level order traversal: ");
    bTree.printLevelOrder (rootNode);

}

public static TreeNode createBinaryTree() {

    TreeNode rootNode = new TreeNode(40);
    TreeNode n20 = new TreeNode(20);
    TreeNode n10 = new TreeNode(10);
    TreeNode n30 = new TreeNode(30);
    TreeNode n40 = new TreeNode(40);
    TreeNode n50 = new TreeNode(50);
    TreeNode n60 = new TreeNode(60);
    TreeNode n70 = new TreeNode(70);

    n40.left = n20;
    n40.right = n60;

    n20.left = n10;
    n20.right = n30;

    n60.left = n50;
    n60.right = n70;
    return rootNode;
}

}