This is related to BE Project
The objective is to create a shared object library file (or .so) and implementing java file to execute the required functions from library file.
It can be done by using Java Native Interface (JNI). To know more about it go to http://www.cprogramming.com/tutorial/shared-libraries-linux-gcc.html#fn:1 or http://www.yolinux.com/TUTORIALS/LibraryArchives-StaticAndDynamic.html or http://web.archive.org/web/20120419230023/http://java.sun.com/docs/books/jni/html/start.html
For compiling java file:
$ javac IPStructure.java
$ javah -jni IPStructure
For compiling C file
$ gcc -fPIC -o libip.so -shared -I /usr/lib/jvm/java-7-openjdk-amd64/include
-I /usr/lib/jvm/java-7-openjdk-amd64/include/linux/ IPStructure.c
It creates a shared object library "libip.so"
$ export LD_LIBRARY_PATH = (current-directory):$LD_LIBRARY_PATH
$ java IPStructure