Class Calculator calculates basic operations, namely, addition, subtraction, multiplication and division of two numbers.

Calculator.java

package com.company;
import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Calculator {

    public static void main(String[] args) {
        // write your code here
        int a, b;
        char opr;
        char choice;
        boolean n = true;
        while (n = true) {
        System.out.println("enter first number");
        Scanner scan = new Scanner(System.in);
        a = scan.nextInt();
        System.out.println("enter second number");
        b = scan.nextInt();
        System.out.println("enter the operation you want to perform");
        opr = scan.next().charAt(0);
                switch (opr) {
                    case '+':
                        System.out.println(a + b);
                        break;
                    case '-':
                        System.out.println(a - b);
                        break;
                    case 'X':
                        System.out.println(a * b);
                        break;
                    case '/':
                        System.out.println(a / b);
                        break;
                    default:
                        System.out.println("operation is invalid");
                        break;
                }
                System.out.println("Do you want to continue? Y/N");
                choice = scan.next().charAt(0);
                if (choice == 'Y'|| choice== 'y')
                    continue;
                if(choice== 'N' || choice== 'n')
                    break;
        }
    }

}