finalize and other approaches that use GC knowledge of objects lifetime have a couple of nuances: visibility: do you guarantee that all the writes methods of object o made are visible to the finalizer (i.e., there is a happens-before relationship between the last action on object o and the code performing finalization)? reachability: how do … Read more
While I’ve used JNI-C++ bridging in the past (only a little though) – it can be a bit ugly. You might want to consider using SWIG to help you generate all the messy boiler plate code.
There are samples in the android-ndk-r5 folder + there is a nice step-by-step tutorial: https://developer.android.com/ndk/samples/index.html No excuses, dude. You just have to read (take a look at the Exploring the hello-jni Sample section).
EDIT: Since I got another crash report yesterday for one of my apps I dug a bit deeper into the matter and found a third very likely explanation for that problem: Google Play Partial APK Update Goes Wrong To be honest, I did not know about that feature. The APK file name suffix “-2.apk” made … Read more
There is a much simpler way to do all of this. Let’s say that your prebuilt library is called “libprebuilt.so” In the project folder of the new project you want to only include the prebuilt library, do something like: mkdir -p jni/libprebuilt cp libprebuilt.so jni/libprebuilt Then, just create a jni/libprebuilt/Android.mk file: LOCAL_PATH := $(call my-dir) … Read more
Try javah -jni com.example.JavaHowTo where com.example is your package. You also need to run javah from the directory containing com/example/JavaHowTo.class e.g. if your structure is /home/user/com/example/JavaHowTo.class run javah from /home/user
Apart from the problem that *mut Any/*const Any are fat pointers, there is also a fact that native JNI functions use double indirection when accessing JNINativeInterface structure: struct JNINativeInterface_; typedef const struct JNINativeInterface_ *JNIEnv; jint (JNICALL *GetVersion)(JNIEnv *env); Here, you can see that JNIEnv is a pointer to JNINativeInterface_ structure which actually contains the fields … Read more
You should try the node-java npm module which is a well-written wrapper over JNI. node-jave doesn’t appear to (yet) have broad adoption, but playing with it, I’ve been impressed with how straightforward and robust it has been. It’s as simple as: var list = java.newInstanceSync(“java.util.ArrayList”); list.addSync(“item1”); list.addSync(“item2”); console.log(list.getSync(1)); // prints “item2” You can do just … Read more
After much trying and crashing of my app, a colleague and I managed to cache and succesfully use the class loader in another, native, thread. The code we used is shown below (C++11, but easily converted to C++2003), posted here since we couldn’t find any examples of the aforementioned “Cache a reference to the ClassLoader … Read more
The storage for the const char* argument to NewStringUTF() is entirely your responsibility: if you allocated test with malloc(), then you need to free() it. So, the snippet you posted is correct. You are corrupting the heap somewhere else. I see conflicting opinions. Some say I should free it myself, some say the VM frees … Read more