Question

我想要完成的是以下...... 询问用户号码并检查用户输入提供的号码是否为7位整数。如果是字符串，则抛出InputMismatchException并再次询问该数字。除了使用正则表达式之外，是否有一种简单的方法可以实现此目的，并且该数字的格式为1234567？另一个问题是如果我输入一个像12345678这样的值，它会因int而被舍入，所以如何避免这种情况。

int number = 0;
try {
    number = scan.nextInt();    // Phone Number is 7 digits long - excludes area code
} catch(InputMismatchException e) {
    System.out.println("Invalid Input.");
    number = validateNumber(number, scan);
} finally {
    scan.nextLine();    // consumes "\n" character in buffer
}

// Method checks to see if the phone number provided is 7 digits long
// Precondition: the number provided is a positive integer
// Postcondition: returns a 7 digit positive integer
public static int validateNumber(int phoneNumber, Scanner scan) {
     int number = phoneNumber;
     // edited while((String.valueOf(number)).length() != 7) to account for only positive values
     // Continue to ask for 7 digit number until a positive 7 digit number is provided
     while(number < 1000000 || number > 9999999) {
        try {
            System.out.print("Number must be 7 digits long. Please provide the number again: ");
            number = scan.nextInt();    // reads next integer provided
        } catch(InputMismatchException e) { // outputs error message if value provided is not an integer
            System.out.println("Incorrect input type.");
        } finally {
            scan.nextLine();    // consumes "\n" character in buffer
        }
     }
     return number;
}

Answer 1

有效的电话号码不一定是整数（例如，包含国家/地区代码的+符号）。所以请改用String。

基本正则表达式的简单示例（7位数字，未验证国家/地区代码等）：

public class Test {
    public static void main(String[] args) {
        Scanner stdin = new Scanner(System.in);


        String telephoneNumber = stdin.nextLine();

        System.out.println(Pattern.matches("[0-9]{7}", telephoneNumber));


    }
}

Answer 2

以下是您最初想法的实例。

public int GetvalidNumber(Scanner scan) {
     int number = 0;
     while(true) {
        try {
            System.out.print("Enter a 7 digit number: ");
            number = scan.nextInt();
            if (number > 0 && Integer.toString(number).length() == 7)
                break;
        } catch(InputMismatchException e) {
            scan.nextLine();
            System.out.println("Invalid input: Use digits 0 to 9 only");
            continue;
        }
        System.out.println("Invalid input: Not 7 digits long");

     }
     return number;
}

验证7位数的电话号码

2 个答案: