1. I doubled click on program.class and it didn't work. Why?

   To run a Java program, you need a Java Virtual Machine to translate the
java bytecode. Go to www.javasoft.com/products to get one. 

2. Should I get JDK or JRE?

   If you ask the question than you should get JRE. JDK is only required to 
compile source code. To run the program from precopiled classes JRE is 
enough. Since you don't know what JDK/JRE are, than you probably don't know 
Java and the precopiled classes will be fine for you. Get JRE, it is much 
smaller than JDK.

3. JRE 1.1.7 or 1.2?

   All my programs were made for Java 1.1. They will probably run under 
JRE 1.2 too but JRE 1.1.7 is smaller than the 1.2 version and you only 
really need the 1.1.7 version. Sooner or later (i.e. when a Linux JDK 1.2 
version will be release) I'll port my program to Java 1.2 and then JRE 1.2 
will probably be required. Bottom line, the choice is yours. 

4. Now what? Do I open Netscape?

   No, my programs are not applets, they won't run from a web browser. 
Open a DOS window (assuming you run Windows), JRE is a text mode program. 
Type jre if you have JRE 1.1.7 or java if you have JRE 1.2. If your comp 
can't find the program you'll have to edit your PATH. 

5. I need to compile the source code now isn't it?

   No. You can use the precompiled classes directly. Java doesn't need to
be recompiled on every OS. The source code is just there for curious
people. Just type java/jre program .

6. When I run JRE 1.1.* I always get a "Class not found" error message.
Why?

   This is the one I get every day... Use the -cp option! JRE will not 
scan your whole HD looking for program.class. Give it some hint. CP stands 
for Class Path and tells JRE were to look for the .class files. Try
   jre -cp <directory of program.class> program
Don't use the DOS name (like GAMMAP~1.CLA), use just the program name 
(without the .class extension). Ex:
   jre -cp . gammaprog
(btw . is the working directory, for those who didn't know...)

   For those using JRE 1.2, make your way the directory where program.class 
is and try
   java program
The current directory should already be in your CLASSPATH so you don't
need the cp option. If it doesn't work, try editing your CLASSPATH.


7. This is to complicated. Can you crack for me this e-mail address?
   
   NO!


8. This FAQ is stupid and doesn't solve my problem at all! 

   Then send me a e-mail including:
   - The JDK/JRE version you use.
   - Your operating system name and version.
   - A copy and paste of the command line you used to get the error and
     the complete error message or output you got. 


An Eyewitness
aneyewitness@geocities.com
(99/02/22)
