Designing Classes - Java Concepts - page 507

java.lang.System.out.println(x);

Because println is followed by an opening parenthesis, it must be a method
name. Therefore, out must be either an object or a class with a static println
method. (Of course, we know that out is an object reference of type
PrintStream .) Again, it is not at all clear, without context, whether System
is another object, with a public variable out , or a class with a static variable.
Judging from the number of pages that the Java language specification [ 3 ]
devotes to this issue, even the compiler has trouble interpreting these
dot-separated sequences of strings.

To avoid problems, it is helpful to adopt a strict coding style. If class names
always start with an uppercase letter, and variable, method, and package names
always start with a lowercase letter, then confusion can be avoided.

H OW T O 8.1: Programming with Packages

This How To explains in detail how to place your programs into packages. For
example, your instructor may ask you to place each homework assignment into a
separate package. That way, you can have classes with the same name but
different implementations in separate packages (such as homework1.Bank
and homework2.Bank ).

Step 1 Come up with a package name.

Your instructor may give you a package name to use, such as homework1 . Or,
perhaps you want to use a package name that is unique to you. Start with your
e-mail address, written backwards. For example, [e-mail]
becomes edu.sjsu.cs.walters . Then add a sub-package that describes
your project or homework, such as edu.sjsu.cs. walters.
homework1 .

Step 2 Pick a base directory.

The base directory is the directory that contains the directories for your various
packages, for example, /home/walters or c:\cs1

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