java - 为什么我会收到输入无效无限循环？

Question

为什么这会导致我在初始选择无效时陷入无限循环？

while (true) {
    System.out.print("Choice:\t");
    try {
        int choice = scanner.nextInt();
        break;
    } catch (InputMismatchException e) {
        System.out.println("Invalid Input!");
    }
}

输出:

Choice: df
Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!
Choice: Invalid Input!

Answer 1

来自Javadoc :

When a scanner throws an InputMismatchException, the scanner will not pass the token that caused the exception, so that it may be retrieved or skipped via some other method.

因此 "df" 字符串仍在扫描仪中。您必须以某种方式清除它，通过调用 next() 或其他方式。