Chapter 2. The Java Programming Environment

Setting the Execution Path

After you are done installing the JDK, you need to carry out one additional step: add the jdk /bin directory to the execution path, the list of directories that the operating system traverses to locate executable files. Directions for this step also vary among operating systems.

• In UNIX (including Solaris and Linux), the procedure for editing the execution path depends on the shell that you are using. If you use the C shell (which is the Solaris default), then add a line such as the following to the end of your ~/. cshrc file:

  
  set path=(/usr/local/ jdk /bin $path)
  

  If you use the Bourne Again shell (which is the Linux default), then add a line such as the following to the end of your ~/.bashrc or ~/.bash_profile file:

  
  export PATH=/usr/local/ jdk /bin:$PATH
  

  For other UNIX shells , you'll need to find out how to carry out the analogous procedure.

• Under Windows 95/98/Me, place a line such as the following at the end of your c:\autoexec.bat file:

  
  SET PATH=c: \ jdk \ bin;%PATH%
  

  Note that there are no spaces around the = . You must reboot your computer for this setting to take effect.

• Under Windows NT/2000/XP, start the control panel, select System, then Environment. Scroll through the User Variables window until you find a variable named PATH . (If you want to make the Java tools available for all users on your machine, use the System Variables window instead.) Add the jdk \bin directory to the beginning of the path, using a semicolon to separate the new entry, like this:

  
  c:\ jdk \bin; other stuff
  

  Save your settings. Any new console windows that you start have the correct path.

Here is how you test whether you did it right:

Start a shell window. How you do this depends on your operating system. Type the line

java -version

and press the ENTER key. You should get a display such as this one:

java version "5.0"
Java(TM) 2 Runtime Environment, Standard Edition
Java HotSpot(TM) Client VM

If instead you get a message such as "java: command not found", "Bad command or file name", or "The name specified is not recognized as an internal or external command, operable program or batch file", then you need to go back and double-check your installation.

Installing the Library Source and Documentation

The library source files are delivered in the JDK as a compressed file src.zip , and you must unpack that file to get access to the source code. We highly recommend that you do that. Simply do the following:

mkdir src
cd src

jar xvf ../src.zip

TIP

The src.zip file contains the source code for all public libraries. To obtain even more source (for the compiler, the virtual machine, the native methods , and the private helper classes), go to http://www.sun.com/software/communitysource/j2se/java2/index.html.

The documentation is contained in a compressed file that is separate from the JDK. You can download the documentation from http://java.sun.com/docs. Several formats (.zip, .gz, and .Z) are available. Choose the format that works best for you. If in doubt, use the zip file because you can uncompress it with the jar program that is a part of the JDK. Simply follow these steps:

Installing the Core Java Program Examples

You should also install the Core Java program examples. You can download them from http://www.phptr.com/corejava. The programs are packaged into a zip file corejava.zip . You should unzip them into a separate directory—we recommend you call it CoreJavaBook . You can use any zip file utility such as WinZip (http://www.winzip.com), or you can simply use the jar utility that is part of the JDK. If you use jar , do the following:

jar xvf corejava.zip

Navigating the Java Directories

In your explorations of Java, you will occasionally want to peek inside the Java source files. And, of course, you will need to work extensively with the library documentation. Table 2-1 shows the JDK directory tree.

Table 2-1. Java Directory Tree

The two most useful subdirectories for learning Java are docs and src . The docs directory contains the Java library documentation in HTML format. You can view it with any web browser, such as Netscape.

TIP

Set a bookmark in your browser to the file docs/api/index.html . You will be referring to this page a lot as you explore the Java platform.