calling exception.printStackTrace() from JNI

Question

The problem is to find out which Java functions call some JNI function. In Java, this would be achieved with new Exception.printStackTrace(), but this must be done from a native (JNI) function.

Since the easiest way to find your own code later is to publish it in the 'net, I post both the question and the answer.

Answer 1

The JNI analog of new Exception.printStackTrace() is:

//#include <android/log.h>
//#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG  , "~~~~~~", __VA_ARGS__)
//#define DLOG(...) __android_log_print(ANDROID_LOG_DEBUG  , "~~~~~~", __VA_ARGS__)
void printStackTrace(JNIEnv *env) {
LOGD("###################################################################################printStackTrace{");
    jclass cls = env->FindClass("java/lang/Exception");
    if (cls != NULL) {
        jmethodID constructor = env->GetMethodID(cls, "<init>", "()V");
        if(constructor != NULL) {
            jobject exc = env->NewObject(cls, constructor);
            if(exc != NULL) {
                jmethodID printStackTrace = env->GetMethodID(cls, "printStackTrace", "()V");
                if(printStackTrace != NULL) {
                    env->CallObjectMethod(exc, printStackTrace);
                } else { DLOG("err4"); }
            } else { DLOG("err3"); }
            env->DeleteLocalRef(exc);
        } else { DLOG("err2"); }
    } else { DLOG("err1"); }
    /* free the local ref */
    env->DeleteLocalRef(cls);
LOGD("###################################################################################printStackTrace}");
}

Answer 2

By the way, you are able to throw an exception from native layer to Java:) Something like this:

jint throwOutOfMemoryError( JNIEnv *env, char *message ){
    jclass       exClass;
    char *className = "java/lang/OutOfMemoryError" ;

    exClass = (*env)->FindClass( env, className );
    if ( exClass == NULL ){
        return throwNoClassDefError( env, className );
    }
    return (*env)->ThrowNew( env, exClass, message );
}

Or if you have an instance of Exception, just throw it into Java layer, and then get a stack trace in Java.