Java - 菜单循环和数学计算

Question

我正在开发一个程序，该程序将为用户提供一个菜单，允许他们选择一个选项，然后要求不同的数字根据他们的菜单选择进行计算。我已经从程序的基本轮廓开始，但我需要帮助来实现循环并使其工作。

这是迄今为止我的代码:

import java.util.Scanner;

public class LB04Alexander {

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    System.out.println("This program will perform several types of calculations.");
    System.out.println();
    System.out.println("-MENU-");
    System.out.println("Select from the following menu options:");
    System.out.println("1 - Compute integer powers of a number");
    System.out.println("2 - Compute a factorial");
    System.out.println("3 - Compute a square root");
    System.out.println("4 - Compute a cube root");
    System.out.println("5 - Compute an exponential");
    System.out.println("6 - Compute the sine of an angle");
    System.out.println("7 - Compute the cosine of an angle");
    System.out.println("8 - Convert a positive integer to binary");
    System.out.println("9 - Exit");
    System.out.println("Please enter the number corresponding to your choice:");

    int menuChoice = input.nextInt();
    while (menuChoice >= 1 && menuChoice <= 9); {
        switch (menuChoice) {
        case 1:
            System.out.println("You have chosen to compute integer powers of a number.");
            System.out.println("Please enter any number for the base:");
            double base1 = input.nextDouble();
            System.out.println("Now, enter a non-negative integer for the exponent:");
            int exponent1 = input.nextInt();
            if (exponent1 < 0)
                System.out.println("Error: exponent is negitive.");
            else
                System.out.println(base1 + "^" + exponent1 + " = " + "");
            break;
        case 2:
            System.out.println("You have chosen to compute a factorial (n!) of a non-negative integer.");
            System.out.println("Please enter a non-negitive integer for n:");
            long fact = input.nextLong();
            int result = 1; 
            if (fact < 0) 
                System.out.println("Error: integer is negitive.");
            else if (fact >= 127)
                System.out.println("Error: Answer too large to calculate");
            else
                for (int i = 1; i <= fact; i++) {
                    result = result * i;
                }
            System.out.println(fact + "! = " + result );
            break;
        case 3:
            System.out.println("You have chosen to compute a square root.");
            break;
        case 4:
            System.out.println("You have chosen to compute a cube root.");
            break;
        case 5:
            System.out.println("You have chosen to compute an exponential.");   
            break;
        case 6:
            System.out.println("You have chosen to compute the sine of an angle."); 
            break;
        case 7:
            System.out.println("You have chosen to compute the cosine of an angle.");   
            break;
        case 8:
            System.out.println("You have chosen to convert a positive integer to binary");  
            break;
        case 9:
            System.out.println("You have chosen to exit");
            System.out.println("Program LB04Alexander is now terminating...");
            input.close();
            System.out.println("The program has ended. Goodbye.");
            break;
        default:
            System.out.println("Invalid menu choice, please try again.");
            break;

        } }


}
}

我遇到的第一个问题是让菜单以正确的方式循环。它要么不起作用，要么永远循环。

Answer 1

while (menuChoice >= 1 && menuChoice <= 9);

去掉那个分号。当您的选择满足条件时，它将永远循环。如果没有，它将在打印出无效的菜单选择，请重试。后立即退出(因为没有任何情况匹配)。