java.lang: A collection of language-related classes, such as Object and String, organized in the java package’s lang subpackage java.lang.ref: A collection of reference-related language classes ...

For example, suppose package physics contains a Math class that’s identical to java.lang ‘s Math class in that it implements the same PI constant and trigonometric methods.

The choice is a personal decision. I have more experience programming Java than Perl. After a long and difficult thought process, I decided to start in Java, reasoning that if I later needed to add ...