Variable parameter class?

Question

The following code

    public static void main(String[] args) {
        fun(new Integer(1));
    }
    static void fun(Object ... a) {
        System.out.println(a.getClass());
    }

gives the output :-

class [Ljava.lang.Object;

What class is this?

Answer 1

An Object[] array.

To get the runtime type information:

a.getClass().isArray() -> true
a.getClass().getComponentType().getName() -> java.lang.Object

Answer 2

according to the JVM specifications it is simply an array of java.lang.Object:

• [ means a monodimensional array
• LfullyQualifiedName; means a class, L; is just syntax

Answer 3

This is how varargs (methods with a variable number of arguments) work in Java - the varargs argument will look like an array inside the method.