Can I get the memory address on the data from the static JNI field? For example, I have 2 situations: First: Second: The examples are very simple. I just want to get the memory address on the static field data, without using GetStaticObjectField and etc. It is possible? Answer Fields in the JVM have no addres…
Tag: java-native-interface
Socket binding through JNI
I try to open a socket connection on a Linux machine through JNI. If I combine Java_Socket_socket and Java_Socket_bind in same C function, the JNI call works perfectly, but it doesn’t work when I run methods sequentially. This is my code Java code Output: If I create C program from this code, and as reg…
JVMTI Invoke toString(); on an Java object from C++ code
So, I was trying to invoke the toString(); method on an object (in this case an enum). This immediately crashed my application. I am assuming that, since the toString(); method isn’t declared directly in the enum but inherited from the Object class (Enum in this case) it is not able to find the method a…
Unexpected behaviour when inserting values into jobjectArray in JNI
Im trying to create a 1D jobjectArray. When printing from inside the loop, “args” array prints correct values but once it is out of the loop, only the last element gets printed repeatedly. This is “args” jobjectArray declaration: This is the loop used to insert values into the jobjectA…
Intellij ignores java Compiler additional compiler options
I have a java 11 project which has some native functions. I am trying to generate the corresponding Header-files by adding ‘-h myDir’ to the additional compiler options in Intellij but it seems like IntelliJ does not even look for those. I am going to: Files > Setting > Build,Execution,Deplo…
Calling a Java variadic function from C through the JNI
I am currently working on creating some Java bindings for a C library I work on. One of our C-structs has a char buffer that is a file system path. After calling the C function, the buffer is correctly populated. I want to take the buffer and convert it to a java.nio.file.Path member on the Java object. I am …
java.lang.Error: Invalid memory access on 32 bit Windows
I have JNA wrapper for a C DLL. It works fine, except when used on a Windows 32-bit system. Here is a simplified example: I created JNA bindings as follows: The first function SetData() works fine on both 32-bit as well as 64-bit Windows, but the second function crashes on Windows 7 32-bit. I tried using Nati…
Difference between “native” keyword and @HotSpotIntrinsicCandidate annotation
Why use one over another and vice-versa? Which is more performant? Answer The javadoc comments for the @HotSpotIntrinsicCandidate annotation say the following: “The @HotSpotIntrinsicCandidate annotation is specific to the HotSpot Virtual Machine. It indicates that an annotated method may be (but is not …
error: JNINativeMethod nfptr throwing invalid conversion from jobjectarray* to void*
I hava following simple jni application: when i compile the code as follow it give me “error: invalid conversion from jobjectarray* to void*” Answer as @Michael said, just need a void* casting:
JNI 8 C++ : Thread attach and detach And async callback
How to async call Java method from std::thread ? Let’s assuming this is a IM bot sdk, Because it’s logic basicly a IM bot sdk. The most importtant is: How to async call java method and callback native. There is logic flow at the bottom, Maybe helpful. For example: Receive message A “backup&#…