variadic-functions

The following code simply uses a null reference as a varargs parameter. package currenttime; import java.util.Arrays; public class Main { private static void temp(String...str) { System.out.println(Arrays.asList(str)); } public static void main(String[] args) { temp(null,null); temp(null); } } The first call to the method temp(null, null); displays [null, null] means that str[0]=null and str[1]=null . but the later call to temp(null); causes the NullPointerException to be thrown which appears that the str itself is null . If it's type cast to String something like this temp((String)null); , it

I'm currently trying to get my head around some of the things I can do with variadic template support. Let's say I have a function like this - template <typename ... Args> void foo(Args ... a) { int len = sizeof...(tail); int vals[] = {a...}; /* Rest of function */ } /* Elsewhere */ foo(1, 2, 3, 4); This code works because I assume beforehand that the arguments will be integers, but obviously will fail if I provide something else. If I know that the parameter packs will contain a particular type in advance, is there some way that I can do without the templating and have something like - void

I haven't quite found an elegant way to solve this issue. I have an abstract class that several other classes are inheriting with an abstract method that can contain anywhere from zero to 4-5 arguments of varying types. public abstract class Item { public abstract void use(); } For instance, I have a Book class that inherits this and takes no arguments when overriding use(), I have a Key class that inherits and takes a String and a Queue as arguments when overriding, etc... I've tried using generics but I have to input the number used, such as Item, when it actually depends on the class.