Basic calculator in Java

Question

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 1

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("+")) {

Answer 2

Here is simple code for calculator so you can consider this
import java.util.*;
import java.util.Scanner;
public class Hello {
    public static void main(String[] args)
    {
        System.out.println("Enter first and second number:");
        Scanner inp= new Scanner(System.in);
        int num1,num2;
        num1 = inp.nextInt();
        num2 = inp.nextInt();
        int ans;
        System.out.println("Enter your selection: 1 for Addition, 2 for substraction 3 for Multiplication and 4 for division:");
        int choose;
        choose = inp.nextInt();
        switch (choose){
        case 1:
            System.out.println(add( num1,num2));
            break;
        case 2:
            System.out.println(sub( num1,num2));
            break;      
        case 3:
            System.out.println(mult( num1,num2));
            break;
        case 4:
            System.out.println(div( num1,num2));
            break;
            default:
                System.out.println("Illigal Operation");


        }



    }
    public static int add(int x, int y)
    {
        int result = x + y;
        return result;
    }
    public static int sub(int x, int y)
    {
        int result = x-y;
        return result;
    }
    public static int mult(int x, int y)
    {
        int result = x*y;
        return result;
    }
    public static int div(int x, int y)
    {
        int result = x/y;
        return result;
    }

}