Vfrdtyky

So for my cs class we need to make a family tree with nodes with two nodes as roots. Every-time a node is created it has a unique id and the counter will keep increasing for every new node. I have a question regarding instantiating a class and setting items to null and counting every time a new node is created.

public class Node<T> implements Comparable<Node<T>> {

// instance variables

static int instanceCounter = 0;

int id = 0;

private T element;

private Node<T> fparent;

private Node<T> sparent;

private List<Node<T>> children;





public Node() {

    instanceCounter++;

    id = instanceCounter;

    this(null, null, null, null, null); // -> this does not work

}



public Node(T element) {

    this.element = element;

    instanceCounter++;

    id = instanceCounter;

}



public Node(T element, Node<T> fparent, Node<T> sparent, List<Node<T>> children) {

    instanceCounter++;

    id = instanceCounter;

    this.element = element;

    this.setFparent(fparent);

    this.setSparent(sparent);

    this.setChildren(children);

}

However this works:

   public Node() {

    this(null, null, null, null, null);

    instanceCounter++;

    id = instanceCounter;

}

What I want is :

Node 1 : Id = 1

Node 2 : Id = 2

Node 3 : Id = 3

but this what I get when the node instantiated with nothing in the parameters:

Node 1 : Id = 2

Node 2 : Id = 3

Node 3 : Id = 4

instanceCounter is incremented twice when you call the default constructor. You should change your default constructor code to.

public Node() {

    instanceCounter++;

    id = instanceCounter;

    //No call required here as all elements are already null

}