Calculator.java

// Build a basic Calculator using Java 

import java.util.Scanner;

public class Calculator
{
    public static void main(String[] args)
    {
        // Take input from the user till user does not press X or x
        Scanner in = new Scanner(System.in);
        int ans = 0;

        while(true)
        {            
            System.out.println("Enter the operator :- ");
            char op = in.next().trim().charAt(0); // take the operator as an input
            
            if(op == '+' || op == '-' || op == '*' || op == '/' || op == '%')
            {
                //input two numbers 
                System.out.println("Enter the two numbers :- ");
                int num1 = in.nextInt();
                int num2 = in.nextInt();

                if(op == '+')
                {
                    ans = num1 + num2;
                }

                if(op == '-')
                {
                    ans = num1 - num2;
                }

                if(op == '*')
                {
                    ans = num1*num2;
                }

                if(op == '/')
                {
                    if(num2 != 0)
                    {
                       ans = num1/num2;
                    }   
                }

                if(op == '%')
                {
                    ans = num1 % num2;
                }
            }
            else if (op == 'x' || op =='X')
            {
                break;
            }
            else
            {
                System.out.println("Invalid Operation!");
            }

            System.out.println(ans);
        }
        
    }
}