java - Java 中的基本计算器

Question

我正在尝试用 Java 创建一个基本的计算器。我对编程很陌生，所以我正在努力适应它。

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));
        }


    }
}

这是我的代码。它提示输入数字和操作，但同时显示答案？

Answer 1

从 if 语句中删除分号，否则后面的代码将独立并始终执行:

if (operation == "+");
                     ^

同样对Strings使用.equals，==比较Object引用:

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