How to edit, compile and run
Open up your favorite text editor, (gedit, emacs, or vi, refer to this quick manual question 1),
create a file with .java extension. For example, I could create a simple
java program like the following:
public class Test
public static void
Saved with a name: Test.java, note: your class name and the source
file name has to have the same name before the extension if the class is the one
which has the public access modifier. Also, by convention, your class name should start
with an up case letter.
Our java installation is in /usr/local/jdk1.5.0/bin, which requires being
included in user’s PATH environment variable. If you are a computer major
student, your path should be already set up for using those java tools, (if
not, refer to quick start HowTo manual question 2 to set up your property
files to include java and other necessary executables).
the directory that you saved Test.java, type: javac
source_file. For example, you type:
% javac Test.java
will create a java bytecode of our program in the same directory as the
source code, named: “Test” to be ready to execute by JVM
you could use javac options to dynamically define or point out your
sourcepath, and output directory for that particular session,
something like the following:
javac –sourcepath ~/Test.java –d classes
Suppose you are not exactly in your source file directory which is your home
directory and you want the compiled file put in the classes directory.
JVM needs to know
where to load your bytecode, there are two ways to declare class locations to
the JVM. You could set it up in your CLASSPATH environment variables or
declared with the “-cp’ flag option.
could run our program with:
% java Test
% java -cp . Test
prompt if our bytecode or classes file in the current working folder (that is
the case for us since we did not direct the output to a different place).
The only difference between those two commands is for the former, your current
directory has already included in your CLASSPATH, for the latter is not.
set up the CLASSPATH for the current session with whatever the CLASSPATH
value, for our example, we could do the following to dynamically set up the
CLASSPATH variables and execute our program:
% set CLASSPATH=.;%CLASSPATH%
This sets our current directory in the classpath, and appends whatever the
original classpath was.
Now, the CLASSPATH issue is out of our way, we could just simply type:
% java Test
run our sample java program, here comes the ubiquitous first exposure of