Question about ... use

[Janeice DelVecchio]

I have been exposing myself to more things lately. I see a lot of methods that take parameters with ... in them. I know it's not morse code because I'm pretty sure that was depreciated with Java 1.3 (LOL!!)

What does it mean, how is it used, what is it called? (so maybe I can look up more stuff on google one day.... it's not easy to search for '...')

[Ernest Friedman-Hill]

Your search keyword should be "varargs".

Short answer: it's a way to define a method that takes a variable number of arguments, all of the same type.

[Janeice DelVecchio]

I read a bit. It looks like it's sort-of used like an array? Are there benefits to this over using a real array as a parameter?

[Bear Bibeault]

You can just list the elements as parameters rather than collecting them into an array prior to making the call.

[Janeice DelVecchio]

Thanks!

[Jesper de Jong]

Varargs in Java works like a kind of syntactic sugar for arrays. Note that you can change any method that takes an array and change it to a method that takes varargs; to the JVM, the methods will look the same. So you can even change your main() method to this:

public static void main(String... args) {
  // code here
}

[Janeice DelVecchio]

Can you override, like this?

public void methodOne(String[] stuff) {
}

public void methodOne(String ... stuff) {
} 
// or now that I think of it...
public void methodOne(String stuff){
}   

If so, which one gets picked at runtime?

[Henry Wong]

Janeice DelVecchio wrote:Can you override, like this?

If so, which one gets picked at runtime?

Do you mean overload? Then, no. Since var-args with string is just an string array, the compiler will complain that the two methods have the same signature.

Henry

[Mike Simmons]

Janeice: the third version can be coexist with either of the other two, as an overload. But the first two cannot exist in the same class. If you call methodOne("A") (with exactly one argument) then the one-argument version (version 3) will be called in preference to either other version. For any other number of arguments, the one-argument version cannot be called.