JniObject

JniObject is a C++11 class that simplifyies the communication between C++ and java using the jni library.

Using jni directly to call a method and pass a string argument is something like this:

JNIEnv* env; 
java->GetEnv(&env, JNI_VERSION_1_4);
jobject obj;
jclass cls = env->GetObjectClass(env, obj);
jmethodID mid = env->GetMethodID(env, cls, "MethodName", "(Ljava/lang/String;)V");
jstring javaString = env->NewStringUTF(nativeString.c_str());
env->CallVoidMethod(obj, mid, javaString);
env->DeleteGlobalRef(cls);

With JniObject it's as simple as this:

JniObject obj;
obj.callVoid("MethodName", nativeString);

Some of the features of the class include:

• automatic method signature deduction
• automatic singleton references
• java object creation
• methods that return other java objects
• multithreading support
• conversion from std::string to java String
• conversion from std::vector to and from java arrays and List
• conversion from std::map to and from java Map

Read this blog post for a more in depth look into it.