AppFortranExample

Example of linking fortran code with java code using JNI. This example passes values from a java method to a fortran subroutine and returns some values back via reference to the java calling method.

This is a working example that leverages the work done by Willie Wheeler at https://medium.com/wwblog/java-fortran-integration-using-jni-7376879f45cd and development work at https://www.gemsoftware.org Geotechnical Engineering Modelling Software (GEMS)

Enhancements

1. Common gradle build file for mac and windows
2. Supports 32b and 64b generation
3. Supports JDK v1.8 and above. (jdk 1.8 is required for 32b code while jdk11/jdk 17 is recommended for 64b
4. Library for passing 2 dimensional arrays between java & fortran. The library takes care of the row-column difference in storing data in arrays

Prerequisites

• gfortran for windows you can get gfortran by installing MinGW-w64 or MinGW-w32.

• Java. You can get open jdk from https://adoptium.net/

• Gradle build https://gradle.org (version < 8.0)

Getting the source

Download and unzip the folder from the github repo https://github.com/s6ch13/AppFortranExample

You can also fork the repository

Contents :

README.md

LICENSE

settings.gradle

build.gradle - build file

/src/main/fortran - contains fortran sources

/src/main/c - contains c sources

/src/main/java - contains java sources

edit the build.gradle to point to the correct java & gfortran versions. You only need the files for the versions you are compiling for

Compiling

$gradle build

BUILD SUCCESSFUL in 13s

12 actionable tasks: 12 executed

$

This generates the jar file - AddNumbers-mac.jar which can be executed.

The compiled fortran/c libraries are at build/libs/

$ls

AddNumbers-mac.jar README.md build settings.gradle LICENSE bin build.gradle src

build/libs/mac$ls

lib_addnumbers_driver.so

Running

$java -jar AddNumbers-mac.jar

Example of executing a fortran subroutine from java

5 + 6 = 11

1.0 2.0

3.0 4.0

+

1.0 2.0

3.0 4.0

=

2.0 4.0

6.0 8.0