What happens when I throw a C++ exception from a native Java method?

Question

Suppose I\'m embedding Sun\'s JVM in a C++ application. Through JNI I call a Java method (my own), which in turns calls a native method I implemented in a shared library.

Answer 1

I would label that as undefined behavior. Propagation of exceptions back to C code (that's what is running the JVM) is undefined behavior.

On Windows, compilers have to use Microsoft's Structured Exception Handling to implement exceptions, so C++ exceptions will be "safely" caried through C code. However, that C code is not written with exceptions in mind, so you will get a crash if you're lucky, and inconsistent state and resource leaks if you aren't.

On other platforms, well, I don't know, but it can't be any prettier. When I write JNI code, I wrap every C++ function in a try block: even if I don't throw, I still might get some of the standard exceptions (std::bad_alloc comes to mind, but others are possible too).