java - int 值的验证

Question

我试图打印一条消息说“错误”，然后每次用户输入非 int 的内容时都有机会输入该值。

我有以下代码:

do {

    System.out.println("Enter last name: ");
    lastName = input.next();

    System.out.println("Enter first name: ");
    firstName = input.next();

    do {
        System.out.println("Enter exam 1 score: ");
        if (input.hasNextInt()) {
            ex1 = input.nextInt();

            System.out.println("Enter exam 2 score: ");
            ex2 = input.nextInt();

            System.out.println("Enter exam 3 score: ");
            ex3 = input.nextInt();

            valid = true;

        } else {
            System.out.println("Incorrect choice. Write the score in numbers." + "\n");
            valid = false;
            input.next(); // Prevents infinite loop
        }
    } while (!valid);

只有当用户在考试 1 中犯错时，这似乎才能正常工作，但如果他们在考试 2 或 3 中犯了错误，就会出现错误。

非常感谢您的帮助。

Answer 1

尽量不要一次又一次地编写相同的代码。使用循环。

final int MAX_SCORES = 3;

while (true) {
    System.out.println("Enter last name: ");
    String lastName = input.next();

    System.out.println("Enter first name: ");
    String firstName = input.next();

    int scores = new int[MAX_SCORES];
    for (int i = 0; i < MAX_SCORES; ) {
        System.out.printf("Enter exam %d score: ", i + 1);
        if (input.hasNextInt()) { 
            scores[i++] = input.nextInt(); // increment 'i' after assignment
        } else {
             System.out.println("Incorrect choice. Write the score in numbers.\n");
             // Loop will repeat at same value of 'i'
        }
    }  

    System.out.println("Again? (Y/N)");
    if (input.next().equalsIgnoreCase("n")) break; // Prevents infinite loop
}