如何处理斐波那契数列的无效输入

Question

我正在尝试创建一个斐波那契数列生成器，其中所有无效输入案例在要求用户重试之前都会有响应。

public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("The Fibonacci Sequence is the series of whole positive numbers where the next number is found by adding up the two numbers before it. \nGive it a try!");
        double number = 0; //
        boolean error;

            do {

                try {
                    error = false;
                    System.out.println("Enter a number to use as an upper limit. The Fibonacci Sequence will be generated up to that number.");
                    number = in.nextDouble();
                    if (number % 1 != 0 || number < 0) {
                        System.err.println("The Fibonacci Sequence only works with positive whole numbers, please enter a positive integer.");
                    } else {
                        System.out.println("The Fibonacci Sequence is: ");
                        int i = 0;
                        int f0 = 0;
                        int f1 = 1;
                        int fn;
                        double value = 0; // changed this to double which is redundant since value is not used
                        do {
                            fn = f0 + f1;
                            System.out.print(f0 + " ");
                            f0 = f1;
                            f1 = fn;
                            value = number - f0;
                            i++;
                        } while (f0 <= number);
                    }
                } catch (Exception e) {
                    System.out.println("The Fibonacci Sequence only works with positive whole numbers, please enter a positive integer.");
                    error = true;
                }
            }

                while (number < 0 || number % 1 != 0 || error) ;

    }

但是，当我在 do-while 循环中使用 try/catch 时，我会在 catch 和输入提示中得到消息的无限循环。

斐波那契数列仅适用于正整数，请输入正整数。 输入一个数字作为上限。将生成最多该数字的斐波那契数列........

我在Java方面还不是很先进，所以现在我想找到一个使用这个逻辑的解决方案，只是找到一种方法来修复我的代码。谢谢！

Answer 1

它适用于任何情况，除非您输入非数字。它会循环，因为输入缓冲区中仍然有一个值，因此错误不断重复。因此，您需要删除 catch 块中的输入，如下所示：

catch (Exception e) {
                    System.out.println("The Fibonacci Sequence only works with positive whole numbers, please enter a positive integer.");
                    error = true;
                    in.nextLine();  // <-- Remove problem input
                }

顺便说一句，既然你只需要正整数，为什么你会提示双打呢？您可能想做：

int number;
// then later

number = in.nextInt();