SystemsProgrammingAndOperatingSystem/Codes/Group A/Assignment-A3/A3.java

// Importing basic stuff
import java.io.*; // Used for I/O operations
import java.util.*; // Contains basic utilities

class A3 {
  // Class name has to be same as file name for Java

  static {
    // Used for loading the .so (on Linux) or .dll (on Windows) file when running
    // This is the main so called "dynamic library"
    System.loadLibrary("A3");
  }

  // Function declaration
  // private indicates the function is private, duh!
  // Use of native indicates the function body will be written in a language other than Java, such as C/C++
  private native int add(int a, int b); // For addition
  private native int sub(int a, int b); // For subtraction
  private native int mul(int a, int b); // For multiplication
  private native int div(int a, int b); // For division

  public static void main(String[] args) { // the main function
    Scanner sc = new Scanner(System.in); // For taking input

    int a, b;// Declaring variables for calculation
    int choice = 0; // Declaring variable for switch-case

    // Take input for a and b values
    System.out.print("\nValue of a:\t");
    a = sc.nextInt();
    System.out.print("\nValue of b:\t");
    b = sc.nextInt();

    // Main menu
    while (true) {
      System.out.println("----- MAIN MENU -----");
      System.out.println("1 -> Addition");
      System.out.println("2 -> Subtraction");
      System.out.println("3 -> Multiplication");
      System.out.println("4 -> Division");
      System.out.println("5 -> Exit");
      System.out.println("Choose an option:\t");
      choice = sc.nextInt();

      switch (choice) {
      	case 1:
          new A3().add(a, b);
          break;
	case 2:
	  new A3().sub(a, b);
	  break;
	case 3:
	  new A3().mul(a, b);
	  break;
	case 4:
	  new A3().div(a, b);
	  break;
	case 5:
	  System.out.println("## END OF CODE");
	  System.exit(0);
	default:
	  System.out.println("Please choose a valid option.");
	  break;
      }
    }
  }
}