varargs and the '...' argument

Question

Consider the method declaration:

String.format(String, Object ...) 

The Object ... argument is just a reference to an array of Objects. Is there a way to use this method with a reference to an actual Object array? If I pass in an Object array to the ... argument - will the resultant argument value be a two-dimensional array - because an Object[] is itself an Object:

Object[] params = ....; // Make the array (for example based on user-input) String s = String.format("%S has %.2f euros", params); 

So the first component of the array (Which is used in the String.format method), will be an array and he will generate:

[class.getName() + "@" + Integer.toHexString(hashCode())]  

and then an error because the array size is 1.

The bold sequence is the real question.
This is a second question: Does a ... array/parameter have a name?

Answer 1

From the docs on varargs:

The three periods after the final parameter's type indicate that the final argument may be passed as an array or as a sequence of arguments.

So you can pass multiple arguments or an array.

The following works just fine:

class VarargTest {   public static void main(String[] args) {     Object[] params = {"x", 1.2345f};     String s = String.format("%s is %.2f", params);     System.out.println(s); // Output is: x is 1.23   } }