I'm implementing an API an have a method which you pass a list of paths where the program reads resources from
public void importFrom(String... paths) {
}
I'm using varargs to make calling the method as convenient as possible to the user, like so
obj.importFrom("/foo", "/foo/bar);
Is this an appropriate use of varargs? Or is passing in an array better?
Rules for varargs:There can be only one variable argument in the method. Variable argument (varargs) must be the last argument.
Varargs are useful for any method that needs to deal with an indeterminate number of objects. One good example is String. format . The format string can accept any number of parameters, so you need a mechanism to pass in any number of objects.
Arrays and varargs are two completely different things. The only relationship is that varargs is implemented using arrays. Talking about the "difference between arrays and varargs" is like talking about the difference between between sugar and cake.
There can be only one variable argument in a method. Variable argument (Varargs) must be the last argument.
In your case varargs is just fine. You don't really need to make an array of the paths that you will be importing because there's nothing you want to do with these paths other than to pass them along to your importFrom
method.
The varargs functionality saves you from having to explicitly create an array solely for the purpose of passing a collection of values to a one-off method, which you do appear to have here.
BTW, you can still pass in an array if you want to
public class VarargsDemo {
public static void f(String... args) {
for (String s: args) {
System.out.println(s);
}
}
public static void main(String[] args) {
String[] english = new String[]{"one", "two", "three"};
f(english);
f("uno", "dos", "tres");
}
}
Because the behavior is the same, the difference comes down to a (probably minor) question of what you want the method signature to "say". When you declare a method to take an explicit array parameter, it's almost as if you want to stress that you want to operate on an array object, something that has been defined outside the method and has its own existence and importance outside the method, and one in which, perhaps, operations like indexing matter. When declaring the method with varargs, its as if you are saying "just give me a bunch of items".
Then again, this doesn't have to be true; the JVM doesn't know the difference, all it sees is an array at run time. Many programmers won't bother splitting hairs over the intent of the method signature. Varargs is all about making the calls convenient.
That said, the main limitation of varargs is that such a parameter must be the last one of the method. In your case this is not a problem, but in general it is something to consider.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With