Question

我正在尝试编写一个带有2个函数的简单计算器（现在用）。我在Eclipse中使用Java。我无法得到我目前正在努力工作的东西。我希望只有菜单项作为自己的功能，然后在接受entryChoice后将case切换为自己的功能。当我按原样运行此代码并进行选择时，它所做的只是重复“输入两个数字......”或者，如果我将userInput分隔成在entryChoice传递后要打印的每个案例，它就会中断。有什么建议吗？

public static void main(String[] args) {
    // TODO Auto-generated method stub
    displayMenu();

    Scanner scanChoice = new Scanner(System.in);
    int entryChoice = scanChoice.nextInt();

    while (entryChoice != 7)
    {
        userSelection(entryChoice);
    }

    System.exit(0); 
}

public static void displayMenu()
{
    System.out.println("Please select from the following choices:");
    System.out.println();

    System.out.println("1) Addition");
    System.out.println("2) Subtraction");
    System.out.println("3) Multiplication");
    System.out.println("4) Division");
    System.out.println("5) Raise to a Power");
    System.out.println("6) Square Root");
    System.out.println("7) Exit Program");

    System.out.println();
    System.out.println("Enter your choice here: ");

}

public static double userSelection(int entryChoice)
{
    double result = 0;
    System.out.println("Enter two numbers seperated by a space");
    Scanner userInput = new Scanner(System.in);

    double x = userInput.nextDouble();
    double y = userInput.nextDouble();

    switch (entryChoice)
    {

        case 1:
            result = x + y;
            break;

        case 2:
            result = x - y;
            break;

        case 3:
            result = x * y;
            break;

        case 4:
            result = x / y;
            break;

        case 5:
            result = Math.pow(x,y);
            break;

        case 6:
            System.out.println("Enter one number: "); // some kinks to work out here..
            result = Math.sqrt(x);
            break;

        case 7:
            result = 0;
            break;
        default:

    }

    return result;
}

}

Answer 1

我认为你想要的是以下内容：

public static void main(String[] args) {
    // TODO Auto-generated method stub

    int entryChoice = -1;
    while (entryChoice != 7)
    {
        displayMenu();

        Scanner scanChoice = new Scanner(System.in);
        entryChoice = scanChoice.nextInt();
        if (entryChoice != 7)
            System.out.println(userSelection(entryChoice));
    }

    System.exit(0); 
}

public static void displayMenu()
{
    System.out.println("Please select from the following choices:");
    System.out.println();

    System.out.println("1) Addition");
    System.out.println("2) Subtraction");
    System.out.println("3) Multiplication");
    System.out.println("4) Division");
    System.out.println("5) Raise to a Power");
    System.out.println("6) Square Root");
    System.out.println("7) Exit Program");
    System.out.println();
    System.out.println("Enter your choice here: ");


}

public static double userSelection(int entryChoice)
{
    double result = 0;
    System.out.println("Enter two numbers seperated by a space");
    Scanner userInput = new Scanner(System.in);

    double x = userInput.nextDouble();
    double y = userInput.nextDouble();

    switch (entryChoice)
    {

        case 1:
            result = x + y;
            break;

        case 2:
            result = x - y;
            break;

        case 3:
            result = x * y;
            break;

        case 4:
            result = x / y;
            break;

        case 5:
            result = Math.pow(x,y);
            break;

        case 6:
            System.out.println("Enter one number: "); // some kinks to work out here..
            result = Math.sqrt(x);
            break;

        default:

    }

    return result;
}

Answer 2

 public static void main(String[] args) {
    // TODO Auto-generated method stub

    displayMenu();

    Scanner scanChoice = new Scanner(System.in);
    int entryChoice = scanChoice.nextInt();

    while (entryChoice != 7) {

        System.out.println(userSelection(entryChoice));
        displayMenu();
        entryChoice = scanChoice.nextInt();
    }

    System.exit(0);
}

public static void displayMenu() {
    System.out.println("Please select from the following choices:");
    System.out.println();
    System.out.println("1) Addition");
    System.out.println("2) Subtraction");
    System.out.println("3) Multiplication");
    System.out.println("4) Division");
    System.out.println("5) Raise to a Power");
    System.out.println("6) Square Root");
    System.out.println("7) Exit Program");
    System.out.println();
    System.out.println("Enter your choice here: ");
}

public static double userSelection(int entryChoice) {
    Scanner userInput = new Scanner(System.in);
    double x = 0;
    double y = 0;
    double result = 0;
    if (entryChoice == 6) {
        System.out.println("Enter one number: ");
        x = userInput.nextDouble();

    } else {
        System.out.println("Enter two numbers seperated by a space");

        x = userInput.nextDouble();
        y = userInput.nextDouble();
    }
    switch (entryChoice) {

    case 1:
        result = x + y;
        break;

    case 2:
        result = x - y;
        break;

    case 3:
        result = x * y;
        break;

    case 4:
        result = x / y;
        break;

    case 5:
        result = Math.pow(x, y);
        break;

    case 6:
        result = Math.sqrt(x);
        break;

    case 7:
        result = 0;
        break;
    default:

    }

    return result;
}

Answer 3

请尝试这个，它按照您的期望工作

import java.util.*;
class Calculator
{
public static void main(String[] args) {
    // TODO Auto-generated method stub
    displayMenu();
}

public static void displayMenu()
{
    System.out.println("Please select from the following choices:");
    System.out.println();

    System.out.println("1) Addition");
    System.out.println("2) Subtraction");
    System.out.println("3) Multiplication");
    System.out.println("4) Division");
    System.out.println("5) Raise to a Power");
    System.out.println("6) Square Root");
    System.out.println("7) Exit Program");

    System.out.println();
    System.out.println("Enter your choice here: ");
    Scanner scanChoice = new Scanner(System.in);
    int entryChoice = scanChoice.nextInt();

    while (entryChoice != 7)
    {
        userSelection(entryChoice);
     }

    System.exit(0); 
}

public static double userSelection(int entryChoice)
{
    double result = 0;
    System.out.println("Enter two numbers seperated by a space");
    Scanner userInput = new Scanner(System.in);

    double x = userInput.nextDouble();
    double y = userInput.nextDouble();

    switch (entryChoice)
    {

        case 1:
            result = x + y;
        System.out.println("Result is :"+result);
            break;

        case 2:
            result = x - y;
        System.out.println("Result is :"+result);
            break;

        case 3:
            result = x * y;
        System.out.println("Result is :"+result);
            break;

        case 4:
            result = x / y;
        System.out.println("Result is :"+result);
            break;

        case 5:
            result = Math.pow(x,y);
        System.out.println("Result is :"+result);
            break;

        case 6:
            System.out.println("Enter one number: "); // some kinks to work out here..
            result = Math.sqrt(x);
        System.out.println("Result is :"+result);
            break;

        case 7:
            result = 0;
            break;
        default:

    }
displayMenu();

    return result;
}
}

对于简单的计算器而言，菜单功能和外壳开关功能存在问题

3 个答案: