→gedit DLL.java

import java.io.*;
import java.util.*;

class DLL{
 static {
 System.loadLibrary("DLL");
 }
 private native int add1(int a,int b);
 private native int sub1(int a, int b);
 private native int mult1(int a,int b);
 private native int div1(int a,int b);
 public static void main(String[] args){
 Scanner sc=new Scanner(System.in);
 int a,b,ch;
 System.out.print("\\n Enter value of a: ");
 a=sc.nextInt();
 System.out.print("\\n Enter value of b: ");
 b=sc.nextInt();
 do
 {
 System.out.println("\\n Enter your choice:  ");
 ch=sc.nextInt();
 switch(ch)
 {
 case 1:new DLL().add1(a,b);
 break;
 case 2:new DLL().sub1(a,b);
 break;
 case 3: new DLL().mult1(a,b);
 break;
 case 4: new DLL().div1(a,b);
 break;
 default:System.out.println("Your choice is wrong.");}
 
 }while(ch<5);

}
}

→javac DLL.java

→gedit DLL.c

#include <jni.h>
#include <stdio.h>
#include "DLL.h"

JNIEXPORT jint JNICALL Java_DLL_add1(JNIEnv *env, jobject obj, jint a, jint b) {
    int result = a + b;
    printf("\\n%d + %d = %d\\n", a, b, result);
    return result;
}

JNIEXPORT jint JNICALL Java_DLL_sub1(JNIEnv *env, jobject obj, jint a, jint b) {
    int result = a - b;
    printf("\\n%d - %d = %d\\n", a, b, result);
    return result;
}

JNIEXPORT jint JNICALL Java_DLL_mult1(JNIEnv *env, jobject obj, jint a, jint b) {
    int result = a * b;
    printf("\\n%d * %d = %d\\n", a, b, result);
    return result;
}

JNIEXPORT jint JNICALL Java_DLL_div1(JNIEnv *env, jobject obj, jint a, jint b) {
    int result = (b != 0) ? (a / b) : 0;
    printf("\\n%d / %d = %d\\n", a, b, result);
    return result;
}

→javac DLL.java →javac -h . DLL.java →java -version //openjdk version "11.0.27" 2025-04-15 →gcc -shared -fPIC -I/usr/lib/jvm/java-11-openjdk-amd64/include -I/usr/lib/jvm/java-11-openjdk-amd64/include/linux DLL.c -o libDLL.so

→java -Djava.library.path=. DLL