JNI Hello World

HelloWorld.c

#include "HelloWorld.h"

JNIEXPORT void JNICALL Java_HelloWorld_sayHello
  (JNIEnv *env, jclass class)
{
        puts("Hello from C world");
}

HelloWorld.java

class HelloWorld {

        static {
                System.loadLibrary("HelloWorld");
        }
               
        public static native void sayHello();

        public static void main(String[] args) {
                sayHello();
        }
}

Makefile

JAVA_HOME = /opt/java6

.PHONY: all clean run

all: HelloWorld.class libHelloWorld.so

HelloWorld.class: HelloWorld.java
	javac $<

HelloWorld.h: HelloWorld.class
	javah HelloWorld

HelloWorld.c: HelloWorld.h

libHelloWorld.so: HelloWorld.c
	gcc -fPIC -shared -Wall -o $@ $< -I$(JAVA_HOME)/include -I$(JAVA_HOME)/include/linux

run:
	LD_LIBRARY_PATH=. java HelloWorld

clean:
	rm -rf HelloWorld.class HelloWorld.h libHelloWorld.so