Triple Dot (...) Syntax in Java? Meaning and conversions?

Question

I have this AVL tree with a balance method:

private void setBalance(Node... nodes) {
    for (Node n : nodes)
        n.height = height(n.right) - height(n.left);
}

It uses a (...) syntax I have not encountered before. I can't find it on google or SO. It seems to be some type of list syntax, or array. Looks like something I would find in ruby.

Could someone knowledgeable in Java's syntax explain this code to me, and perhaps show me a version without the ... syntax?

Thanks.

You can treat `Node...` as `Node []`, or just change the `Node...` to `Node []` and `setBalance` will still work. Take a look at the [Arbitrary Number of Arguments](https://docs.oracle.com/javase/tutorial/java/javaOO/arguments.html). — Watermel0n, Jul 14 '15 at 01:20

score 7 · Accepted Answer · edited May 23 '17 at 11:44

7

These are varargs . Basically same are arrays but can be zero to many. More info that might also assist.

edited May 23 '17 at 11:44

Community

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answered Jul 14 '15 at 01:21

Shahzeb

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Actually it can zero to many (at least in Java 8), so you could call `setBalance()` ;) . To do one to many, you might use `private void setBalance(Node one, Node... many)` or something equivilent :P – MadProgrammer Jul 14 '15 at 01:26
You are right just tested in Java 7 Zero to many :) – Shahzeb Jul 14 '15 at 01:29
Still a good answer ;) – MadProgrammer Jul 14 '15 at 01:37

Triple Dot (...) Syntax in Java? Meaning and conversions?

1 Answers1