TreeImplementationBFS

import java.util.*;
public class TreeImplementationBFS {

    public static void main(String[] args) {
        Node<Integer> root = createTree();
        printTree(root);
    }

    private static Node<Integer> createTree() {
        Node<Integer> root = new Node<>(1);

        Node<Integer> node1 = root.addChild(new Node<Integer>(2));
        Node<Integer> node2 = root.addChild(new Node<Integer>(3));
        Node<Integer> node3 = root.addChild(new Node<Integer>(4));

        Node<Integer> node11 = node1.addChild(new Node<Integer>(5));
        Node<Integer> node12 = node1.addChild(new Node<Integer>(6));
        Node<Integer> node31 = node3.addChild(new Node<Integer>(7));
        Node<Integer> node32 = node3.addChild(new Node<Integer>(8));

        Node<Integer> node111 = node11.addChild(new Node<Integer>(9));
        Node<Integer> node112 = node11.addChild(new Node<Integer>(10));
        Node<Integer> node311 = node31.addChild(new Node<Integer>(11));
        Node<Integer> node312 = node31.addChild(new Node<Integer>(12));


        return root;
    }

    private static <T> void printTree(Node<T> node) {
       Queue<Node<T>> q = new LinkedList<Node<T>>();
       q.add(node);

       while (!q.isEmpty()) {
           Node<T> n =  q.remove();
           System.out.print(" " + n.getData());
           if (n.getChildren().size() !=0) {
               q.addAll(n.getChildren());
           }
    }


    }
}
    class Node<T> {

        private T data = null;

        private List<Node<T>> children = new ArrayList<>();

        private Node<T> parent = null;

        public Node(T data) {
            this.data = data;
        }

        public Node<T> addChild(Node<T> child) {
            child.setParent(this);
            this.children.add(child);
            return child;
        }

        public void addChildren(List<Node<T>> children) {
            children.forEach(each -> each.setParent(this));
            this.children.addAll(children);
        }

        public List<Node<T>> getChildren() {
            return children;
        }

        public T getData() {
            return data;
        }

        public void setData(T data) {
            this.data = data;
        }

        private void setParent(Node<T> parent) {
            this.parent = parent;
        }

        public Node<T> getParent() {
            return parent;
        }

    }