Question

在下面的代码中，我希望程序通过try catch循环，以允许用户在输入无效输入（即字母而不是int）时重新输入第一个添加的答案。目前代码显示catch语句，但也会继续执行该程序，并显示if if语句中的System.out.println("Sorry incorrect, please guess again");，我不想要。有人可以帮我解决这个问题吗？非常感谢！

    public static void add() {

        // Setting up random
        Random random = new Random();

        // Declaring Integers
        int num1;
        int num2;
        int result;
        int input;
        input = 0;
        // Declaring boolean for userAnswer (Defaulted to false)
        boolean correctAnswer = false;
        do {
            // Create two random numbers between 1 and 100
            num1 = random.nextInt(100);
            num1++;
            num2 = random.nextInt(100);
            num2++;

        do{ 
            // Displaying numbers for user and getting user input for answer
            System.out.println("Adding numbers...");
            System.out.printf("What is: %d + %d? Please enter answer below",
                    num1, num2);
            result = num1 + num2;

                try {
                    input = scanner.nextInt();
                } catch (Exception ex) {
                    // Print error message
                    System.out.println("Invalid number entered for addition...");
                    // flush scanner
                    scanner.next();
                    correctAnswer = false;
                }
        }while(correctAnswer=false);

            // Line break for code clarity
            System.out.println();

            // if else statement to determine if answer is correct
            if (result == input) {

                System.out.println("Well done, you guessed corectly!");
                correctAnswer = true;
            } else {

                System.out.println("Sorry incorrect, please guess again");
                correctAnswer=false;
            }
        } while (!correctAnswer);

Answer 1

错误在于：

while(correctAnswer=false)

你需要

while(correctAnswer==false)

您所拥有的是false到correctAnswer的分配 - 一个始终为false的表达式，因此循环永远不会继续。写a==false的更常见方法是!a，所以我会将循环条件更正为

while(!correctAnswer)

更“流利”地阅读。

当然，现在需要在循环顶部设置correctAnswer = true以避免无限次迭代。

尝试捕获循环问题

1 个答案: