Please may you tell me how to use java.lang class

As far as I understand, java.lang is a package (not a class) that has a bunch of classes in it that are directly available to be used without the requirement to import the package.

If you have made int, double, String variables, etc., you have already used the java.lang package. Refer to the URL below for a list of the classes that java.lang contains.

http://docs.oracle.com/javase/1.4.2/...e-summary.html