I searched for this but all I found were GCJ pages or GCC for C/C++ pages, but how do I compile and run java programs with the gcc-java package installed. And does this require any other gcc stuff? (can't remember if there is a base gcc package, but if there is do I need it?)

Isn't it exactly (almost maybe ) like compiling g++?. To compile:

gcj -c -g -O Hello.java

to link it, use the command:

gcj --main=Hello -o Hello Hello.o

The only thing different is the "--main=Hello" thing, that, as far as I understand, refers to the main class from your code(?). That should create an executable called "Hello", that you should be able to run with ./Hello. Otherwise, make it executable (chmod +x Hello).

If you want to create .class files like javac does, use -C as argument (gcj -C).

Last time I've checked, gcj had support to java.lang, java.io, java.util, java.net, java.security, java.sql and java.math packages, but not graphical ones like AWT and Swing.

As you see, there're many limitations using gcj, specially when it comes down to gui's applications. Personally, I love Java, but I dislike many things coming from Sun, one of them, is letting Java being closed source, thus, not very suitable for Open Source projects. Let's keep out fingers crossed for gcj

GCJ is the Java front-end for GCC. GCJ requires that you also have the g++ package installed (which is almost always present along with your GCC installation).

The GCJ page ( http://gcc.gnu.org/java/ ) has some good info to get you started.

Is gcc-java (the package I see in slack 9.1) the same thing as gcj?

so to make a .class is it

gcj -C -g -O Hello.java
or
gcj -C Hello.java
???
is gcj -c -g -O Hello.java the command for machine native code??? What is the point of this I don't understand.

So with gcj is it impossible to do GUI or just really really hard because you have to right the AWT and Swing code yourself?? Does the code stay platform independent? And are there any non Sun compilers that support GUI classes?

vdogvictor, read up on the gcj site. Read the FAQ's there. Also go to the LQ wiki and read there about Java (there's some info on GCJ).

You can do GUI code with GCJ, but it's a bit limited at the moment. You write it by-hand, and it's not difficult.

As megamanX was saying, using the gcj command is analogous to using the g++ command (for compiling C++ code), with a few small exceptions (such as the --main option).