建议，编写社会保障代码 [英] Advice, writing a social security code

问题描述

我是 Java 新手，我们需要编写一个程序，用户以 XXXXXXXXX 的形式输入社会保障代码，并以 XXXX-XX-XXX 的形式返回.例如，如果代码是 123456789，它将作为 123-45-6789 返回给他们.

Im new to java and my class we need to write a program where the user inputs there social security code in the form of XXXXXXXXX and it returns it in the form of XXXX-XX-XXX. For example if there code was 123456789 it would be returned to them as 123-45-6789.

这是我所拥有的，我想使用子字符串来完成它.

Here is what I have, I would like to use substrings to finish it off.

导入 java.util.Scanner;

import java.util.Scanner;

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

    String name;
    int ssn;
    System.out.print ("Enter nine digit social security number without dashes: ");
    ssn= reader.nextInt();
    System.out.print("Your formatted social security number is: ");
    System.out.println(snn.substring(,) );

   }
   }

这是新代码

导入 java.util.Scanner;

import java.util.Scanner;

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

    String name;
    String Ssn="ssn";

    System.out.print ("Enter nine digit social security number without dashes: ");
    Ssn= reader.nextLine();
    System.out.print("Your formatted social security number is: ");
    System.out.println (Snn.substring(0,3) +"-"snn.substring(4,6) + "-"snn.substring(7,9);

}
}

推荐答案

实际上更合适的方法是使用 Matcher 带有 Pattern 代表一个 regex 包含社会保险号的子组作为 捕获组:

Actually a more appropriate way to do this would be to use a Matcher with a Pattern representing a regex containing the subgroups of the social security number as capturing groups:

final Pattern ssnFormat = Pattern.compile("^(\\d{3})(\\d{2})(\\d{4})$");

Matcher m = ssnFormat.matcher(ssn);  // make ssn a string!

if (m.find()) {
    System.out.printf("%s-%s-%s%n", m.group(1), m.group(2), m.group(3));
} else {
    System.err.println("Enter a valid social security number!");
}

如前所述，社会保险号虽然可以表示为整数，但实际上是一串数字:作为数字没有意义.因此，您应该将其存储为 String 而 not 存储为 int.

As noted, a social security number, while representable as an integer, is really a string of digits: it's meaningless as a number. Therefore, you should store it as a String and not as an int.

现在，在您的新代码中，您几乎完成了，但仍有一些问题:

Now, in your new code, you're almost there, but still have a few issues:

• 是String，不是string.
• 既然 ssn 是一个字符串，你不能将它分配给 reader.nextInt() 的结果，因为它返回一个 int.相反，您需要使用 reader.nextLine().
• 第二次和第三次 substring() 调用的范围略有偏离.参考方法的文档.

• It's String, not string.
• Now that ssn is a string, you can't assign it to the result of reader.nextInt(), since that returns an int. Instead, you'll want to use reader.nextLine().
• The ranges of the second and third substring() calls are slightly off. Refer to the method's documentation.

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