Main.java

import java.util.Scanner;

public class Main {
   public static void main(String[] args) {
       int a;
       int b;
       String operation;
       int answer;
       Scanner scanner = new Scanner(System.in);
       System.out.println("Welcome to my calculator");
       System.out.println("Enter first number:");
       a = scanner.nextInt();
       System.out.println("Enter second number:");
       b = scanner.nextInt();
       System.out.println("Enter operation:");
       operation = scanner.next();
       if ("+".equals(operation)) {
           answer = add(a, b);
           System.out.println("Answer is: " + answer);
       } else {
           System.out.println("Unsupported operation");
       }
   }

   private static int add(int a, int b) {
       return a + b;
   }
   
   private static int sub(int a, int b) {
       return a - b;
   }
}