Java^TM cannot do it all. Sometimes you need to write system-specific code. This can be done use JNI (Java Native Interface). It allows your Java programs to use functions written in C. Here's the way I got it to work under Linux.

1. Write your java program

   class Hello {
   
     public native void printGreeting();
   
     static {
       System.loadLibrary("hello");
     }
   
     public static void main(String[] args) {
       Hello hello = new Hello();
       hello.printGreeting();
     }
   }
   

2. Compile it (javac Hello.java)
3. Generate the C header, Hello.h (javah Hello)
4. Using the prototype in the header file, create the C file, Hello.c

   #include "Hello.h"
   #include <stdio.h>
   
   JNIEXPORT void JNICALL Java_Hello_printGreeting(JNIEnv *env, jobject obj) {
     printf("Hello World\n");
   }
   

5. Generate a shared library

   gcc -o libhello.so -shared -Wl,-soname,libhello.so -I/usr/local/java/include -I/usr/local/java/include/linux Hello.c -static -lc
   

6. Set your library path (setenv LD_LIBRARY_PATH $LD_LIBRARY_PATH:. or whatever is appropriate for your shell/system)
7. Run (java Hello)