使用while循环java检查来自扫描程序的输入是否为int

Question

我基本上希望下面的while循环检查输入是否为整数。它不能包含小数，因为它指向一个数组。如果输入的值为十进制，则应再次提示用户。问题是在使用此代码开始while循环之前，我得到两个提示。有任何想法吗？

      System.out.print("Enter month (valid values are from 1 to 12): ");
    Scanner monthScan = new Scanner(System.in);
    int monthInput = monthScan.nextInt();
    // If the month input is below 1 or greater than 12, prompt for another value
    while(monthInput<1 || monthInput>12 || !monthScan.hasNextInt())
    {
        System.out.print("Invalid value! Enter month (valid values are from 1 to 12): ");
        monthInput = new Scanner(System.in).nextInt();
    }

谢谢

编辑：当前输出给出以下内容：

Enter month (valid values are from 1 to 12): 2
2

请注意，即使这是一个有效值，我也必须两次输入两次。

Answer 1

对您的程序进行小的修改即可解决问题

 System.out.print("Enter month (valid values are from 1 to 12): ");
        Scanner monthScan = new Scanner(System.in);
       int monthInput = monthScan.nextInt();
        // If the month input is below 1 or greater than 12, prompt for another value
        while((monthInput<1 || monthInput>12) )
        {
            System.out.print("Invalid value! Enter month (valid values are from 1 to 12): ");

            monthInput = monthScan.nextInt();
        }
        System.out.println("I am here");

输出：

Enter month (valid values are from 1 to 12): -5
Invalid value! Enter month (valid values are from 1 to 12): -5
Invalid value! Enter month (valid values are from 1 to 12): -2
Invalid value! Enter month (valid values are from 1 to 12): 5
I am here

希望对您有帮助。