In this class, we will be using a combination of a text editor and the command line java compiler, javac, and java runtime, java. You may use any text editor you like, but the official "supported" text editor for this class is JEdit. Our default OS will be Linux. You are free to install the proper tools on your own computer, but your programs MUST compile and run on the standard lab setup.
The following is a brief tutorial to show you how to use these tools in the lab.
Step 1: Writing your programs with jEdit
jEdit is very similar to Notepad and other basic text editors. To
run jEdit, simply type
jedit at the Linux command
jEdit contains built-in help if you get stuck. You can also check out its web site, http://www.jedit.org.
Step 2: Compiling your programs with the Java compiler
We will be using Sun's Java compiler, javac, in this course, and compiling from the command line. The basic syntax is
> javac Class1.java Class2.java ...
Class1.java, Class2.java are the names of the
files containing your Java source code.
javac has several options that you may need to use from
time to time, but most of the time you will just need to type, in the
same directory as your source files,
javac followed by the name(s) of your source file(s).
If you have many source files to compile, you can list the names of
the files in one or more files and use this as the argument to
javac. For example, if you have source files
Class1.java, Class2.java, Class3.java, Class4.java,
Class5.java, you can create a file, say
that looks like this:
Class1.java Class2.java Class3.java Class4.java Class5.java
and then type at the command line:
> javac @MyClasses
The Java compiler will then compile all of the class files listed in
MyClasses. If the program(s) compiled successfully, the
command prompt will just return. Otherwise, you will see a list of
warnings and error appear.
Once you've compiled your program files successfully, you should
see a number of
.class files in your working directory.
In the example above, you would see
Class2.class, etc, alongside the
Class2.java, etc, files. These
.class files are
the compiled files that the computer will actually run, in the
Step 3: Running your programs using the Java command line
To run your program, the command
java is used. You
java on the
.class file containing your
main method. For example, if your
method is in the program file
MyMainClass.java, you would
type the following at the command line to run the program:
Do not include the
.class extension here!
If there are any run-time errors, these will show up in the window
from which you ran
java. Repeat steps 1-3 until these
errors go away.
If you are still having problems, check out this page of common errors.