J++ was missing several key interoperability features like JNI (instead it required idiosyncratic native code that no JVM could run) and RMI (it couldn't make r

J++ was missing several key interoperability features like JNI (instead it required idiosyncratic native code that no JVM could run) and RMI (it couldn't make remote procedure calls at all, unless you roll your own). And rather than sticking to their own packages, they deliberately poisoned standard classes (I think this even included java.lang.System!) with nonstandard methods whose absence would prevent your code from even loading on a conforming JVM.