Java简单计算器，了解s​​witch和方法兼容性

Question

我在暑期类有一项作业是制作一个简单的计算器，但我在一些事情上遇到了麻烦。

开头有一个菜单，询问用户想要做什么，其中一个选项是退出，其中一个选项是对用户输入进行平方。

我遇到的问题是我无法找到用开关退出程序的方法，所以我把它从开关中取出并做了一个条件，这样就可以了。所以，我想这不是什么大问题，除非有人愿意向我展示如何将它包含在交换机中。我现在遇到的问题是对用户输入进行平方。问题是程序询问用户他们想要做什么，然后要求他们输入两个操作数。然而，我只希望它询问一个操作数。因此，我将其放入条件中，它只要求一个操作数，但它似乎不再使用平方方法并计算结果。

非常感谢任何帮助!!

import java.util.Scanner;

public class Driver {

public static void main(String[] args) {

    Menu m = new Menu();
    m.getMenu();

  }    
}       



class Menu {    
    public void getMenu() {
        Scanner scan = new Scanner(System.in);

        System.out.println("Welcome to 00 Calculator menu, this calculator has the following options:");
        System.out.println("1 - Add " + "\n" + "2 - Subtract" + "\n"
                + "3 - Multiply" + "\n" + "4 - Divide" + "\n" 
                + "5 - Square" + "\n" + "6 - Modulus" + "\n" + "0 - Quit" );
        int optionInt = scan.nextInt();

         if (optionInt == 0) {
            System.out.println("Goodbye!"); 
            return;

        }else if (optionInt == 5) {
            System.out.println("Enter the first number :");
            double num1 = scan.nextDouble();
        }else {
            System.out.println("Enter the first number :");
            double num1 = scan.nextDouble();
            System.out.println("Enter the second number :");
            double num2 = scan.nextDouble();

            double result;
            Action option = new Action();


            switch (optionInt) {
            case 1:
                result = option.addValues(num1, num2);
                option.displayResult(result);
                break;
            case 2:
                result = option.subtractValues(num1, num2);
                option.displayResult(result);
                break;
            case 3:
                result = option.multiplyValues(num1, num2);
                option.displayResult(result);
                break;  
            case 4:
                result = option.divideValues(num1, num2);
                option.displayResult(result);
                break;  
            case 5:
                result = option.squareValues(num1, num2);
                option.displayResult(result);
                break;  
            case 6:
                result = option.modulusValues(num1, num2);
                option.displayResult(result);
                break;          
            default:
                System.out.println("You entered an incorrect option.  Goodbye.");
           } 
        }   
    }
}


class Action {

public double divideValues(double d1, double d2) {
    double result = d1 / d2;
    return result;
}

public double multiplyValues(double d1, double d2) {
    double result = d1 + d2;
    return result;
}

public double subtractValues(double d1, double d2) {
    double result = d1 - d2;
    return result;
}

public double addValues(double d1, double d2) {
    double result = d1 + d2;
    return result;
}

public double squareValues(double d1, double d2) {
    double result = Math.pow(d1, 2);
    return result;
}

public double modulusValues(double d1, double d2) {
    double result = d1 % d2;
    return result;
}

public void displayResult(double result) {
    System.out.println("The answer is " + result);
 }

}

Answer 1

由于您的要求很复杂，退出选项最好保留在原来的位置...

现在，如果您不选择0，则有两种可能性，您需要根据选项需要询问一个或两个值。

在这种情况下，如果 optionInt != 5，那么您需要两个值，但是，您始终需要一个，因此您始终可以要求，例如...

if (optionInt == 0) {
    System.out.println("Goodbye!"); 
    return;
} else {
    System.out.println("Enter the first number :");
    double num1 = scan.nextDouble();
    double num2 = 0;
    if (optionInt != 5) {
        System.out.println("Enter the second number :");
        num2 = scan.nextDouble();
    }
    double result;
    Action option = new Action();


    switch (optionInt) {
    case 1:
        result = option.addValues(num1, num2);
        option.displayResult(result);
        break;
    case 2:
        result = option.subtractValues(num1, num2);
        option.displayResult(result);
        break;
    case 3:
        result = option.multiplyValues(num1, num2);
        option.displayResult(result);
        break;  
    case 4:
        result = option.divideValues(num1, num2);
        option.displayResult(result);
        break;  
    case 5:
        result = option.squareValues(num1); // You will need to update your Action class
        option.displayResult(result);
        break;  
    case 6:
        result = option.modulusValues(num1, num2);
        option.displayResult(result);
        break;          
    default:
        System.out.println("You entered an incorrect option.  Goodbye.");
   } 

}   

读完代码后，您似乎甚至不需要检查退出选项，因为一旦您以任何方式完成操作，您的方法就会退出，因此，您可以简单地执行类似的操作。 ..

if (optionInt != 0) {  
    // Process other options...
}

//... method will exit of it's own accord, you don't need to do anything...

已更新

另一种方法可能是编写一个方法来提示用户输入您需要的值，例如，当您需要它们时......

public double getDouble(String prompt) {
    System.out.println(prompt);
    Scanner scan = new Scanner(System.in);
    double value = scan.nextDouble();
    scan.nextLine();
    return value;
}

public void getMenu() {
    Scanner scan = new Scanner(System.in);

    System.out.println("Welcome to 00 Calculator menu, this calculator has the following options:");
    System.out.println("1 - Add " + "\n" + "2 - Subtract" + "\n"
            + "3 - Multiply" + "\n" + "4 - Divide" + "\n"
            + "5 - Square" + "\n" + "6 - Modulus" + "\n" + "0 - Quit");
    int optionInt = scan.nextInt();
    scan.nextLine();

    double result;
    Action option = new Action();
    switch (optionInt) {
        case 0:
            System.out.println("Good bye!");
            break;
        case 1:
            result = option.addValues(
                    getDouble("Enter the first number :"),
                    getDouble("Enter the second number :")
            );
            option.displayResult(result);
            break;
        case 2:
            result = option.subtractValues(
                    getDouble("Enter the first number :"),
                    getDouble("Enter the second number :")
            );
            option.displayResult(result);
            break;
        case 3:
            result = option.multiplyValues(
                    getDouble("Enter the first number :"),
                    getDouble("Enter the second number :")
            );
            option.displayResult(result);
            break;
        case 4:
            result = option.divideValues(
                    getDouble("Enter the first number :"),
                    getDouble("Enter the second number :")
            );
            option.displayResult(result);
            break;
        case 5:
            result = option.squareValues(
                    getDouble("Enter a number :"),
            );
            option.displayResult(result);
            break;
        case 6:
            result = option.modulusValues(
                    getDouble("Enter the first number :"),
                    getDouble("Enter the second number :")
            );
            option.displayResult(result);
            break;
        default:
            System.out.println("You entered an incorrect option.  Goodbye.");
    }
}