Basic calculator in Java

user2037720 picture user2037720 · Feb 3, 2013 · Viewed 313.5k times · Source

I'm trying to create a basic calculator in Java. I'm quite new to programming so I'm trying to get used to it.

import java.util.Scanner;
import javax.swing.JOptionPane;

public class javaCalculator 
{

    public static void main(String[] args) 
    {
        int num1;
        int num2;
        String operation;


        Scanner input = new Scanner(System.in);

        System.out.println("please enter the first number");
        num1 = input.nextInt();

        System.out.println("please enter the second number");
        num2 = input.nextInt();

        Scanner op = new Scanner(System.in);

        System.out.println("Please enter operation");
        operation = op.next();

        if (operation == "+");
        {
            System.out.println("your answer is" + (num1 + num2));
        }
        if  (operation == "-");
        {
            System.out.println("your answer is" + (num1 - num2));
        }

        if (operation == "/");
        {
            System.out.println("your answer is" + (num1 / num2));
        }
        if (operation == "*")
        {
            System.out.println("your answer is" + (num1 * num2));
        }


    }
}

This is my code. It prompts for the numbers and operation, but displays the answers all together ?

Answer

Reimeus picture Reimeus · Feb 3, 2013

Remove the semi-colons from your if statements, otherwise the code that follows will be free standing and will always execute:

if (operation == "+");
                     ^

Also use .equals for Strings, == compares Object references:

 if (operation.equals("+")) {