Java programs that utilize standard extensions with native libraries are problematic since the extensions are platform dependent. We present general methods that make such programs runnable on multiple platforms in a way that is transparent to the user. We show a detailed example for standalone applications, Web Start programs, and applets with a specific such standard extension. Categories and Subject Descriptors D.3 [Programming Languages, Language Constructs and Features]: Modules, packages General Terms Languages Keywords Java, native libraries, multiple platforms