package com.vaadin.data.provider.hierarchical; import java.io.Serializable; public class Node implements Serializable { private static int counter = 0; private final Node parent; private final int number; public Node() { this(null); } public Node(Node parent) { this.parent = parent; this.number = counter++; } public Node getParent() { return parent; } public int getNumber() { return number; } public String toString() { return number + (parent != null ? " [parent: " + parent + "]" : ""); } }