Question

仅当我输入10个或更多的3和7的数字时才会出现。它来自下面的这个方法，我没有这种方法测试它。这是代码

Scanner input = new Scanner(System.in);
    System.out.print("Enter a positive integer...");
    int num = input.nextInt();

    // Outputs
    System.out.println("Number of digits in number is " + numberDigits(num));
    System.out.println("Number begins with " + firstNum(num));
    System.out.println("Number ends with " + lastNum(num));
    System.out.println("Does number begin with 7? " + beginWith(num, 7));
    System.out.println("Does number begin with 3? " + beginWith(num, 3));
    System.out.println("Does number contain a 7? " + contains(num, 7));
    System.out.println("Does number contain a 3? " + contains(num, 3));
    System.out.println("Is the number divisible by 13? " + divTest(num, 13));
    System.out.println("Is the number divisible by 77? " + divTest(num, 77)); 
    System.out.println("How many times does 7 appear in the number? " + digitAppearances(num, 7));
    System.out.println("How many times does 3 appear in the number? " + digitAppearances(num, 3));

public static int digitAppearances(int num, int x) {

    // Check if num is 0
  if (num <= 0 ) {
    return 0;
  }

// Count number of times x appears
else if (num % 10 == x) {
    return 1 + digitAppearances(num / 10, x);
}
else {
    return digitAppearances(num / 10, x);
}
}

Answer 1

Scanner正在尝试使用the nextInt method阅读int。

调用nextInt()形式的此方法的行为与调用nextInt(radix)完全相同，其中radix是此扫描程序的默认基数。

nextInt（基数）：

<强>抛出：

InputMismatchException - 如果下一个标记与整数正则表达式不匹配，或者超出范围

如果您输入的值大于Integer.MAX_VALUE（约21亿，10位数），那么您将获得InputMismatchException。

如果您想输入最多19位数字，请使用nextLong。

如果要输入任意数量的数字，只需调用next，获取字符串，并验证它只包含数字。在进一步处理之前，您需要将字符数字转换为数字类型。

Java InputMismatchException错误。我该如何解决这个问题？

1 个答案: