ADDITIONAL JAVA TOPICS - Java Programming: From Problem Analysis to Program Design - page 967

example, you could create a directory for the classes you create in this topic. Because
the title of this topic is Java Programming: From Problem Analysis to Program Design, you
could create a directory named jpfpatpd . You could then make subdirectories for
the classes used in each chapter, such as the subdirectory Appendix within the
directory jpfpatpd .
Suppose that you want to create a package to group the classes related to time. You
could call this package clockPackage . To add the class Clock to this package and to
place the package clockPackage within the subdirectory Appendix of the directory
jpfpatpd , you include the following package statement with the file containing the
class Clock (Note that the class Clock is the same as discussed in Chapter 8):

package jpfpatpd.Appendix.clockPackage;

We put this statement before the definition of the class , like this:

package jpfpatpd.Appendix.clockPackage;

public class Clock
{

//put instance variables and methods here

}
The next step is to compile the file Clock.java using the compile command in the IDE
(integrated development environment) you are using.
The following discussion assumes that you have set the Path so that the files javac.exe
and java.exe can be executed from within any subdirectory. Suppose that the file
Clock.java is in the subdirectory c:\jpfpatpd . We assume that you have switched to
the subdirectory c:\jpfpatpd .
If you are using Java 7.0, which contains a command-line compiler, you include the
option -d to place the compiled code of the program Clock.java in a specific directory.
For example, the command:

javac -d c:\jre1.7.0\lib\classes Clock.java

places the compiled code of the program Clock.java in the subdirectory:

c:\jre1.7.0\lib\classes\jpfpatpd\Appendix\clockPackage
Similarly, the following command places the compiled code of the program Clock.java
in the subdirectory c:\jpfpatpd\Appendix\clockPackage :

javac -d c:\ Clock.java

If the directories jpfpatpd , Appendix ,and clockPackage do not exist, then the compiler
automatically creates these directories. Note that for the earlier command to execute
successfully, the subdirectory c:\jre1.7.0\lib\classes must exist. If this subdirectory
does not exist, you must first create it. Also, to be absolutely sure about the correct directory
path, check your system's documentation. Moreover, if you do not use the -d option with
the path of the subdirectory to specify the subdirectory in which to store the compiled code,
then the compiled code is, typically, stored in the current subdirectory.