java-native-interfacekotlin-native

How can I call JNIEnv function from Kotlin/Native


jni.h provide this

struct JNINativeInterface_ {
    ...
    jint (JNICALL *GetVersion)(JNIEnv *env);
    ...
}

to call it in C can be written as

void test(JNIEnv *env){
    // C
    jint version = (*env)->GetVersion(env);

    // C++
    // jint version = env->GetVersion(); 
}

and then how can I do it in kotlin?

fun test(env: CPointer<JNIEnvVar>){
    val version = // how?
}

After searching answer in google there are few example for Kotlin/Native with JNI but they're just basic example please help.

Thanks in advance.


Solution

  • Thanks to Michael.

    Long answer is

    fun test(env: CPointer<JNIEnvVar>){
        // getting "JNINativeInterface_" reference from CPointer<JNIEnvVar> by 
        val jni:JNINativeInterface_ = env.pointed.pointed!!
    
        // get function reference from JNINativeInterface_
        // IntelliJ can help to find existing methods
        val func = jni.GetVersion!! 
    
        // call a function
        var version = func.invoke(env)
    
        // above expression can be simplify as
        version = env.pointed.pointed!!.GetVersion!!(env)!!
    }
    

    hope this can help somebody to understand Kotlin/Native 🙂.