Abstract. As Java is being considered an appropriate environment for
high performance computing, we describe advanced techniques of highly
expressive and efficient combining of Java with existing code in other
languages. We present their example use in developing of Java wrappers
for the lip – a runtime support library which enables easy and portable
parallelization of irregular and out-of-core problems. Sample performance
comparison results of out-of-core computations in Java and C are also
presented.