Exception in thread "main" java.lang.UnsatisfiedLinkError: com.applepark.jni.EventReceiver.startCommEngine(Ljava/lang/String;ILjava/lang/String;)V

Question

I have a EventReceiver.java file (in package com.applepark.jni) that calls a native method startCommEngine(String,int,String) compiled into library named "libevent.so". When the program starts it gives following error:

Exception in thread "main" java.lang.UnsatisfiedLinkError: com.applepark.jni.EventReceiver.startCommEngine(Ljava/lang/String;ILjava/lang/String;)V at com.applepark.jni.EventReceiver.startCommEngine(Native Method) at com.applepark.jni.EventReceiver.start(EventReceiver.java:33) at com.applepark.jni.HelloJNI.main(HelloJNI.java:12)

Following is my EventReceiver.java file:

package com.applepark.jni;

public class EventReceiver {

    static {
        String property = System.getProperty("user.dir");
        System.load(property+"/lib/libevent.so");
        System.out.println("Library 'libevent.so' load successful");
    }

    private String topic = "";
    private String host = "";
    private int port = 0;

    public EventReceiver() {
        this.topic = "/event/#";
        this.host = "192.168.7.116";
        this.port = 1883;
    }

    private native void startCommEngine(String ip, int port, String topic);

    public void start(String ip,int port, String topic) {
        startCommEngine(this.host,this.port,this.topic);
    }

    private native void stopCommEngine();

    public void stop(){
        stopCommEngine();
    }

    private native void publishData(String topic, byte[] data);

    public void publish(String topic, byte[] data){
        publishData(this.topic,data);
    }

}

This is the makefile that was used in compilation:

CLASS_PATH := ../bin/com/applepark/jni
IPATH = /System/Library/Frameworks/JavaVM.framework/Headers
CUST_IPATH = ../src/com/applepark/jni

vpath %.class $(CLASS_PATH)

all : libevent.so

libevent.so : event_receiver.o
    gcc -m64 -Wl, -shared -o $@ $< -lmosquitto

event_receiver.o : nldcs_mqtt_comm.c event_receiver.c  com_applepark_jni_EventReceiver.c               
    gcc -I$(IPATH) -I$(CUST_IPATH) -m64 -c $< -o $@

com_applepark_jni_EventReceiver.h : EventReceiver.class
    javah -jni -classpath $(CLASS_PATH) $*

clean :
    rm event_receiver.o libevent.so

And here is my Native function implementation:

#include <stdlib.h>
#include <stdio.h>
#include "com_applepark_jni_EventReceiver.h"
#include "event_receiver.h"
#include "nldcs_mqtt_comm.h"

JNIEXPORT void JNICALL    Java_com_applepark_jni_EventReceiver_startCommEngine
  (JNIEnv *env, jobject ctx, jstring host_str, jint port, jstring topic) {

    printf("startCommEngine : Initialising the Receiver \n");

}

Can't understand what is going on.