Question

我正在编写一个代码，用户试图找到Triangle的斜边。我的代码首先询问用户他们想从A侧还是B侧开始。我使用Switch方法来覆盖这两种情况。在使用任何一种情况之后我想要我的代码做的是回到起点，直到用户退出。出于某种原因，我的代码只做了一个案例，但没有回到开头开始一个全新的循环。我使用了错误的方法吗？我是不是写了不正确的代码？我该怎么做才能解决它？

import java.util.Scanner;

public class HandleException {
public static void main (String[] args){
    int data= 0;
    int data1= 0;
    int sum= 0;

    Scanner input = new Scanner (System.in);
    //ask user for a command
    System.out.println("Which side would you like to start with A or B");
    String s= input.next();
            char letter= s.charAt(0);

                loop:while (letter!= 'q'){      


    switch (letter){

    //if user inputs 'A'
        case 'a':

            System.out.println("Enter value for side A: ");
            data= input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s=input.next();
                letter=s.charAt(0);
                    if (letter == 'b')
                    System.out.println("Enter Value For side B: ");
                    data1= input.nextInt();
                        System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                        s=input.next();
                        letter=s.charAt(0);
                            if (letter== 'c')
                                sum=data*data+data1*data1;
                                int sumsrt = (int) Math.sqrt(sum);
                                System.out.println("The hypotenuse is:  "+sumsrt);
                                continue;

        //if user inputs 'B'                        
        case 'b':
            System.out.println("Enter value for side B: ");
            data= input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s=input.next();
                letter=s.charAt(0);
                    if (letter == 'a')
                    System.out.println("Enter Value For side a: ");
                    data1= input.nextInt();
                        System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                        s=input.next();
                        letter=s.charAt(0);
                            if (letter== 'c')
                                sum=data*data+data1*data1;
                                int sumsrt1 = (int) Math.sqrt(sum);
                                System.out.println("The hypotenuse is:  "+sumsrt1); 
                                continue;




    }

}
}
}

Answer 1

第一次循环结束后，它会转到第while(letter!= 'q')行和字母值为c

开关中没有匹配值，因此第二次循环将结束并且什么都不做。

它会保持循环，所以你没有机会问下一个System.in

Answer 2

一旦完成斜边计算，你不会要求退出char。这就是为什么程序进入无限循环而不是退出也是你在完成后使用break。

if (letter == 'b')
                    System.out.println("Enter Value For side B: ");
                    data1= input.nextInt();
                        System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                        s=input.next();
                        letter=s.charAt(0);
                            if (letter== 'c')
                                sum=data*data+data1*data1;
                                int sumsrt = (int) Math.sqrt(sum);
                                System.out.println("The hypotenuse is:  "+sumsrt);
                    System.out.println("Press q for quit otherwise enter side ");

                      break;

同样适用于case 'b'

Answer 3

切换案例后再次读取输入。试试这个

import java.util.Scanner;

public class HandleException {
    public static void main(String[] args) {
        int data = 0;
        int data1 = 0;
        int sum = 0;

        Scanner input = new Scanner(System.in);
        // ask user for a command
        System.out.println("Which side would you like to start with A or B");
        String s = input.next();
        char letter = s.charAt(0);

        while (letter != 'q') {

            switch (letter) {

            // if user inputs 'A'
            case 'a':

                System.out.println("Enter value for side A: ");
                data = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'b')
                    System.out.println("Enter Value For side B: ");
                data1 = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'c')
                    sum = data * data + data1 * data1;
                int sumsrt = (int) Math.sqrt(sum);
                System.out.println("The hypotenuse is:  " + sumsrt);
                break;

                // if user inputs 'B'
            case 'b':
                System.out.println("Enter value for side B: ");
                data = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'a')
                    System.out.println("Enter Value For side a: ");
                data1 = input.nextInt();
                System.out.println("Enter next command: A : value for side A; B : Value for side B; C: Calculate; Q : Quit program.");
                s = input.next();
                letter = s.charAt(0);
                if (letter == 'c')
                    sum = data * data + data1 * data1;
                int sumsrt1 = (int) Math.sqrt(sum);
                System.out.println("The hypotenuse is:  " + sumsrt1);
                break;

            }

            System.out.println("Which side would you like to start with A or B");
            s = input.next();
            letter = s.charAt(0);

        }
    }
}

我很难将我的程序循环回到开始新的循环

3 个答案: