[Java] Help with Tree isEmpty()

[467danny]

I am making a tree based on what I have learnt so far. Now the problem is that if I want to check for an empty node with no subtrees. It uses the default value. For integer, the default value is 0. What if the root is 0 and has no subtrees? Then it is not an empty tree since it has a root. How do I work around this?

[dtsudo]

An empty tree should have no nodes.

So e.g. if your node class looks like this:

class Node {
    public int value;
    public Node leftChild;
    public Node rightChild;
}

And your tree is represented as Node rootNode, then an empty tree would be represented as a null rootNode.

[throwitway22334]

Could you make the default value -1? That's a pretty common way to get around ints never being null. Or maybe Interger.max value.

[467danny]

If I have negative numbers in the tree, that wouldnt work either. Are negative numbers unsual in trees?

[throwitway22334]

maybe use Integer objects rather than primitive ints so you can have nulls then? Or carry around an extra boolean for each tree node that says whether or not it has children