The  lp_solve java version was made by automatic C-to-Java converter from the original C++ version by Hartmut Schwab. 

The recent open lp_solve Java versions are implemented as Java wrappers of lp_solve in C++ , 
see LP-5 problem of Software Systems section  of this web-site 

The dieta example using LP-5 java wrapper is in Dieta-5.5 problem  of Discrete Optimization section