How to pass varargs by reference in Java

Question

I\'m writing a method that receives any number of arguments and returns them modified. I have tried with varargs but it doesn\'t work, here you can see a simplified version of t

Answer 1

An array of String[] can be passed to fulfill the vararg requirement - no copy/clone of the array passed as such is made so mutating the array inside .. well, changes that array everywhere. But this is ugly, particularly because it adds a "side-effect, sometimes".

However, you cannot do "by reference"¹ otherwise as a new array is created when arguments are passed normally to a variadic method as in the original code.

// but avoid code like this, if possible
String[] words = {"hello", "world"};
addPrefix(words);
System.out.println("hello: " + words[0] + "  world: " + words[1]);

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¹ It's only Call by Reference if rebinding a parameter changes a binding in the caller, which Java does not support. It doesn't matter if varargs are used or not.