JNINativeMethod.fnPtr

Description

The function pointer.

This should be obtained using Marshal.GetFunctionPointerForDelegate, and delegate should refer to a method annotated with MonoPInvokeCallback attribute and having such signature: static ReturnType MyMethod(IntPtr jniEnv, IntPtr objectOrClass, ...);

// Delegate difinition
delegate void JavaToCs(IntPtr jniEnv, IntPtr klass, int x);

// Method definition
[MonoPInvokeCallback(typeof(JavaToCs))]
static void CsMethod(IntPtr jniEnv, IntPtr klass, int x)
{
    Debug.Log("From Java: " + x);
}

// Array to be passed to AndroidJNI.RegisterNative
var methods = new JNINativeMethod[]
{
    new JNINativeMethod
    {
        name = "csMethod",
        signature = "(I)V",
        fnPtr = System.Runtime.InteropServices.Marshal.GetFunctionPointerForDelegate(new JavaToCs(CsMethod)),
    }
};

// Register method for Java class
AndroidJNI.RegisterNatives(clazz, methods);