java在一个我一直试图制作的简单计算器上遇到了问题

Question

我一直在用一个简单的计算器来计算这些错误 信息：java:编译模块“学习”时出错

Error:(24, 31) java: bad operand types for binary operator '*'
 first type:  java.util.Scanner
  second type: java.util.Scanner


Error:(27, 31) java: bad operand types for binary operator '/'
first type:  java.util.Scanner
second type: java.util.Scanner


 Error:(21, 31) java: bad operand types for binary operator '-'
 first type:  java.util.Scanner
 second type: java.util.Scanner


Error:(18, 31) java: bad operand types for binary operator '+'
 first type:  java.util.Scanner
  second type: java.util.Scanner


Error:(16, 16) java: incompatible types: java.util.Scanner cannot be converted to int

这是我的密码

import java.util.Scanner;

class Main {

public static void main(String[] args) {
    Scanner Operation = new Scanner(System.in);
    Scanner num1 = new Scanner(System.in);
    Scanner num2 = new Scanner(System.in);
    float result = 0;

    System.out.println("What is your first number?");
    int num1int = num1.nextInt();
    System.out.println("What is your second number?");
    int num2int = num2.nextInt();
    System.out.println("What operation would you like to perform?");
    switch (Operation) {
        case "addition":
            result = num1 + num2;
            break;
        case "subtraction":
            result = num1 - num2;
            break;
        case "multiplication":
            result = num1 * num2;
            break;
        case "division":
            result = num1 / num2;
            break;
    }

}

谢谢你们的帮助，伙计们，还有，如果我不应该发布这个，我很抱歉，我是新来的

Answer 1

在你的代码中，你有一行

result = num1 + num2;

尝试将num1和num2相加。给定变量名称，这似乎是合理的，但是当你考虑这些行时，它变得荒谬：

Scanner num1 = new Scanner(System.in);
Scanner num2 = new Scanner(System.in);

你不能添加两个扫描仪，这在理论上没有意义，在实践中更没有意义。我猜你是想这么做的：

result = num1int + num2int;

理论上这很好，但是当你尝试用num1int=3和num2int=4执行这个操作时，你会得到result=0而不是result=0.75：

result = num1int / num2int;

这是因为整数除法总是向0取整。为了避免这种情况，将石膏加倍，如下所示：

result = ((double) num1int) / num2int;

我希望这有助于澄清你的问题。祝你好运

Answer 2

num1和num2不是数字，而是java.util.Scanner类型

您可能会使用num1int和num2int，如下所示：

 switch (Operation) {
    case "addition":
        result = num1int + num2int;
        break;
    case "subtraction":
        result = num1int - num2int;
        break;
    case "multiplication":
        result = num1int * num2int;
        break;
    case "division":
        result = num1int / num2int;
        break;
}

我建议更改名称以反映真实类型，如下所示：

Scanner scannerNum1 = new Scanner(System.in);
Scanner scannerNum2 = new Scanner(System.in);
float result = 0;

System.out.println("What is your first number?");
int num1 = scannerNum1.nextInt();
System.out.println("What is your second number?");
int num2 = scannerNum2.nextInt();
switch (Operation) {
    case "addition":
        result = num1 + num2;
        break;
    case "subtraction":
        result = num1 - num2;
        break;
    case "multiplication":
        result = num1 * num2;
        break;
    case "division":
        result = num1 / num2;
        break;
}

注意：另外，定义两个扫描仪是不必要的。一个就够了