It looks like the Amiga java is planning on using the standard new Amiga
hierarchical shell variable conventions (which I like), so you should be able
to (eventually) do a:

        set java.classpath {/;/sys/j;/classes.zip}

Right now the java shell script completely overrides any value you might have
set java.classpath to, so you need to use the -classpath option for now (which
does work) unless you'd like to modify it.