- 1 year ago
Call fortran dll from java using JNI
To call a Fortran DLL from Java using JNI (Java Native Interface), you need to create a JNI wrapper for the Fortran DLL and then load it into your Java application. The process involves writing C/C++ code to interface with the Fortran DLL and bridge the communication between Java and Fortran. Here's a step-by-step guide:
Write a Fortran DLL:
First, you need to create the Fortran DLL with the functions you want to call from Java. You can use a Fortran compiler like GFortran or Intel Fortran to build the DLL.Create a C/C++ Wrapper:
Write a C/C++ wrapper code that will interface with the Fortran DLL. This C/C++ code will act as a bridge between the Java code and the Fortran DLL.For example, if your Fortran function is named
my_fortran_function
, you need to create a C/C++ function with the same name that will call the Fortran function:c// Wrapper.c
#include <jni.h>
// Declare the Fortran function prototype
extern void my_fortran_function_();
// JNI function to call the Fortran function
JNIEXPORT void JNICALL Java_MyJavaClass_callFortranFunction(JNIEnv *env, jobject obj) {
my_fortran_function_();
}
Create a JNI Header File:
Run the Java Native Interface (JNI) tooljavah
on your Java class that will call the Fortran function to generate a C/C++ header file:javah MyJavaClass
This will create a header file (e.g.,
MyJavaClass.h
) that contains the JNI function signatures.Compile the C/C++ Wrapper and Fortran DLL:
Compile the C/C++ wrapper (Wrapper.c
) and the Fortran DLL to create a shared library.On Windows, use a C/C++ compiler like Visual Studio or MinGW and link with the Fortran DLL to create a
.dll
file.On Linux, use
gcc
org++
with the Fortran library to create a.so
file.Load the Shared Library in Java:
In your Java code, useSystem.loadLibrary()
to load the shared library (the one created from the C/C++ wrapper) before calling the JNI function:javapublic class MyJavaClass {
// Load the shared library
static {
System.loadLibrary("myfortran");
}
// Native method declaration
private native void callFortranFunction();
// Java method that calls the Fortran function via JNI
public void runFortranFunction() {
callFortranFunction();
}
// Main method to test the JNI call
public static void main(String[] args) {
MyJavaClass myJavaObject = new MyJavaClass();
myJavaObject.runFortranFunction();
}
}
Compile and Run the Java Code:
Compile your Java class (MyJavaClass.java
) and run it. Make sure the shared library (.dll
or.so
) is in the library path.
That's it! When you run your Java program, it will load the Fortran DLL through the JNI wrapper and call the Fortran function from Java. Keep in mind that JNI calls can be tricky, so ensure that your C/C++ wrapper code handles the data types and memory correctly to avoid crashes or unexpected behavior.