Is a variable length argument treated as an array in Java?

Yes, if you have a method with a varargs parameter like this:

public void foo(String... names)

and you call it like this:

foo("x", "y", "z");

then the compiler just converts that into:

foo(new String[] { "x", "y", "z"});

The type of the names parameter is String[], and can be used just like any other array variable. Note that it could still be null:

String[] nullNames = null;
foo(nullNames);

See the documentation for varargs for more information.

This does not mean that varargs are interchangeable with arrays - you still need to declare the method to accept varargs. For example, if your method were declared as:

public void foo(String[] names)

then the first way of calling it would not compile.