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License text, setup instructions, and support info do not need to be duplicated into every README, since they're already in the top-level README. They were originally in each sample because the samples used to each be separate Android Studio projects with different requirements that could be checkout out independently in Android Studio. This is no longer the case. Most of the docs also included text along the lines of "This sample uses the new Android Studio with CMake support", which hasn't been new since 2015, so doesn't really need to be said. The prerequisites were mostly not true. Android Studio is not required for any of this. Cloning the repo and running `./gradlew build` is sufficient to build all the samples. They also were not being kept up-to-date at all, since they mostly said "Android Studio 2.2 or newer", which was definitely not true. I'm not what the oldest version of Android Studio that will work here is, but I don't actually test anything but the latest so claiming anything otherwise is just misleading. I haven't pruned or edited any of the real content of the docs. I'm sure there are plenty of edits to be made there and a lot of expansion to do, but those changes will be less mechanical and will happen separately.
Exceptions
This Android sample shows how to handle exceptions across the JNI boundary.
Handling native exceptions
Native exceptions can be caught in JNI methods and re-thrown in the JVM. Because
uncaught native exceptions will cause your app to crash, we recommend catching
all exceptions as a fail-safe. You may also want to catch instances of
std::exception or your own exception interface:
extern "C" JNIEXPORT void JNICALL
Java_com_example_exceptions_MainActivity_throwsException(JNIEnv* env,
jobject /* this */) {
try {
might_throw();
} catch (std::exception& e) {
jniThrowRuntimeException(env, e.what());
} catch (...) {
jniThrowRuntimeException(env, "Catch-all");
}
}
Then, you can do the same in your Java/Kotlin code:
try {
jniMethodThatMightThrow();
} catch (e: java.lang.RuntimeException) {
// Handle exception
}
The hard part here is using the JNI API to throw an exception in the JVM. That
is, implementing jniThrowRuntimeException. We recommend referring to
JNIHelp.h
and
JNIHelp.c
in the Android platform's libnativehelper, from which
exception_helper.h and
exception_helper.cpp are
adapted.
Screenshot
