If you follow the instructions off of gentoo’s website (they are very good instructions) for x86 on 2004.1 then you end up with a system that doesn’t have gcj. Here’s what I did to get it working.

This takes a while to run. I suggest starting the emerge under “screen”. Type `screen’ to start screen and then follow these instructions. If you don’t have screen, type `emerge screen’. If you don’t know what screen is see this post, number 6 on the list.

First, emerge gcc again like this:


USE="java gcj" emerge gcc


At the time, this emerged 3.3.2-r5


sys-devel/gcc
Latest version available: 3.3.2-r5
Latest version installed: 3.3.2-r5


Then create your little java app:

user@server /tmp $ cat HelloWorld.java
public class HelloWorld {
    public static void main(String args[]) {
        System.out.println("hi");
    }
}

Next, compile it like this:

gcj --main=HelloWorld -o Hello HelloWorld.java


Finally, run it:

user@server /tmp $ ./Hello
hi


Then you can move that file to another Linux box (provided all the libc libraries match and other stuff I don’t know about) and run it. Very cool.

More info here:
Linux Journal
GCJ FAQ