Passing several parameters as a single parameter in Java.

Question

I've seen an example of it before, but I've never really found any good reference material dealing with it. I know it's possible to pass in several parameters, ints for example, by defining the method as

public void aMethod(int...a)

But I don't know any more about it than that. I've seen an example, and it returned the average of the ints passed.
Is this an out-dated way of passing parameters? Is it even acceptable to use this? What exactly is the syntax like when doing this? (Some reference material would be great)

Answer 1

It's called varargs (from the C syntax). See Sun's varargs guide for an overview and this JDC Tech Tip for usage. It is not out-dated; it was put in as a feature request since previously you were forced to create an array or list, which was really ugly for supporting something like C's printf.

public void myMethod(String... args) {
    for (String aString:args) {
        System.out.println(aString);
    }
}

Answer 2

You are going to have to pass a list of ints to the method to do this, something like this:

public void aMethod(int[] list)

or this:

public void aMethod(ArrayList<int> list)

It would be nice if Java had something like C#'s params keyword but it doesn't.

Answer 3

How about if you wanted to pass a list of parameters from different types. Can you do that. For example, a use of printf goes like this

printf("%d... %f... %c... %s", intVar, floatVar, charVar, stringVar);

Is there a way to do that in java???