This is about java and graph layout

For java programming there is a dot language parser at http://www.alexander-merz.com/graphviz/

There is old GNU GPL free java source in vgj which can run in the browser as java applet and the source is here in vgj.tar.gz

A saved copy of the original website and manuals is here as vgj homepage

The sfg.c graph layout source in gml4gtk can be compiled to java using c2j.exe which is GNU GPL free software but nobody has seen the source of c2j and it needs a extra runtime, see http://tech.novosoft-us.com/product_c2j.jsp

Maybe can find another better usable solution to compile the C to java