Calculator.java

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/*How to make a calculator using Java?*/
import java.util.Scanner;

public class Calculator {

    public static void main(String[] args) {
        /* declare 3 int type variables num1, num2 and result.
        num1 and num2 will hold the inputs from user and result will hold the calculation result
        by default result have 0 value*/
        int num1, num2, result = 0;

        Scanner scanner = new Scanner(System.in); // Create an object of Scanner class

        System.out.println("Press 1 for Addition");
        System.out.println("Press 2 for Substraction");
        System.out.println("Press 3 for Division");
        System.out.println("Press 4 for Multiplication");

        // infinity loop
        while (true) {

            System.out.println("What you want to perform? Choose between 1 to 4");
            // calcutationType will hold the type of calculation
            int calcutationType = scanner.nextInt();

            System.out.println("Enter First Number");
            num1 = scanner.nextInt(); // initialize num1 variable with first number entered by user.

            System.out.println("Enter Second Number");
            num2 = scanner.nextInt(); // initialize num2 variable with second number entered by user.

            // check calcutationType and perform actions on inputs corresponsing to to calcutationType
            switch (calcutationType) {
                case 1:
                    result = num1 + num2;
                    System.out.println("Addition of "+num1+" and "+num2+" is = " + result);
                    break;

                case 2:
                    result = num1 - num2;
                    System.out.println("Substraction of "+num1+" and "+num2+" is = " + result);
                    break;

                case 3:
                    result = num1 / num2;
                    System.out.println("Division of "+num1+" and "+num2+" is = " + result);
                    break;

                case 4:
                    result = num1 * num2;
                    System.out.println("Multiplication of "+num1+" and "+num2+" is = " + result);
                    break;

                default:
                    System.out.println("You have entered wrong number. Please chooose between 1 to 4");
            }

            System.out.println("Do you want to continue. Press 'Y' to continue or Any other button to exit");

            String exitStatus = scanner.next(); //  to check wheather user want to exit or continue with new values

            if (!exitStatus.equals("Y")) {
                break; // this statement will exit while loop and end the program
            }

        }

    }
}

/*----------OUTPUT----------
Press 1 for Addition
Press 2 for Substraction
Press 3 for Division
Press 4 for Multiplication
What you want to perform? Choose between 1 to 4
2
Enter First Number
6
Enter Second Number
5
Result is = 1
Do you want to continue. Press 'Y' to continue or Any other button to exit
a
*/