Implementing C Native Methods for Java in Linux

To make a class called TestClass that uses a native method called test, follow these steps:

1) Write TestClass.java:
   class TestClass {
        public native void test(); //no body
        static {System.loadLibrary("TestClass");}
    }

2) Write the function test in TestClassImp.c :
    #include <jni.h>
    #include "TestClass.h"
    #include <stdio.h>

void TestClass_test(struct HTestClass *myhandler) {
    printf("OK!\nIt worked\n");
}

3) Now, create the TestClass.h and TestClass.c using javah:
    javah TestClass, to create header file
    javah -stubs TestClass, to create the stub file

4) Use javac and gcc to compile and link:
    javac TestClass.java
    gcc -c -fPIC -I(jdk_path)/include -I(jdk_path)/include/genunix TestClass.c
    gcc -c -fPIC -I(jdk_path)/include -I(jdk_path)/include/genunix TestClassImp.c
    gcc -shared -Wl,-soname,libTestClass.so -o libtestClass.so TestClass.o TestClassImp.o

5) Set the library path:
    export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:.

6) Create the Main.java, just to test:

    class Main {
        public static void main(String[] args) {
            new TestClass().test();
        }
    }

7) Compile Main.java and execute Main.class...
 

These file  contains some files whit examples:

voidtest.tgz : the simplest example
returnint.tgz: an example returning an int
intstringint.tgz:  an int as parameter, access a string directly and returns an int
stringparam.tgz:uses a string as parameter