Verifying if an input string is a correct Social Security Number

Question

Here is the Exact Instructions, but I have already done some of it. I will Write what I need help with at the bottom.

.I want to Write a program that reads in a social security number as a string (including the dashes) in the format DDD-DD-DDDD where D is a digit.

.I need to Write a method: public static boolean validSSN(String s)to check whether a string is in the format of DDD-DD-DDDD. Before I do anything I have to check the length of the input string.

.It should be 11 characters long(including the -'s) and anything else is invalid.

.I need to Write 2 boolean methods: isDigit(char c) and isDash(char c) to help check the format of the input and invoke them in the method body of validSSN.

.In the main method, I need to use a scanner object’s nextLine() method to read an entire line as a string invoke the validSSN method print the input and whether or not it is valid.

Here is what I have so far:

import java.util.Scanner;

public class lab14 {

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

        System.out.println("Enter a Social Security Number");
        int num = SSN.nextInt();

    }
    public static boolean validSSN(String s){
        if 

    }
    public static boolean isDigit(char c){

    }
    public static boolean isDash(char c){

    }

}

So, I have written out the header for the main method, and the header for the boolean method that checks to see if there are 11 characters, a header for a boolean method that checks to see if the numbers are in the right place, and a header for a boolean method that checks to see if the dashes are in the right place. I have imported a Scanner method, and sent out for the user ti imput a social security number.

What I need help with is what to put in the body of each method. I need help to return true if there is 11 digits, if the numbers are in the right place, and if the dashes are in the right place. So If I were to input 123-56-7890, It would say that "123-56-7890 is a valid SSN", and I were to input 123/56/7890 or 123-567-890 it would say that ""123-567-890" or "123-567-890" is not a SSN". Can someone help me with verifying that the input is a SSN.

score 6 · Answer 1 · answered Apr 21 '15 at 06:42

6

Use regex like this :

myString.matches("\\d{3}-\\d{2}-\\d{4}");

answered Apr 21 '15 at 06:42

TheLostMind

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Regex are best suited here. – Raja Apr 21 '15 at 06:44
do I have to import something to use it – lawtonhself Apr 21 '15 at 06:45
how do I make the Imput = to myString? – lawtonhself Apr 21 '15 at 06:48
@lawtonhself This is the best solution, but it doesn't quite fit the specification the you gave (which sounds like a homework problem). Not complaining though. If you ever have to determine if a string is a SSN in production code, this is what you'd use. On the other hand, if you want to get to writing production code, you gotta start with the basics. Just my 2 cents. – Anubian Noob Apr 21 '15 at 06:48
@lawtonhself - Don't use `nextInt()` . use `nextLine()` and read it into `myString` – TheLostMind Apr 21 '15 at 06:49
@lawtonhself - Please update your question with the *latest* code – TheLostMind Apr 21 '15 at 06:54
I still haven't changed anything except for int sum = SSN.nextInt() to int sum = SSN.nextLine() . I am still a little confused. I have to create the 3 different methods, but doesnt the myString.matches("\\d{3}-\\d{2}-\\d{4}"); only use one method? – lawtonhself Apr 21 '15 at 06:56
@lawtonhself - You have to change the code to : `String sum = SSN.nextLine();` and then `sum.matches(matches("\\d{3}-\\d{2}-\\d{4}"));` – TheLostMind Apr 21 '15 at 06:58
So how Do I use sum.matches(matches("\\d{3}-\\d{2}-\\d{4}")); over the 3 methods?import java.util.Scanner; public class lab14 { public static void main(String[] args){ Scanner SSN = new Scanner(System.in); System.out.println("Enter a Social Security Number"); String sum = SSN.nextLine(); } // checks to see if number of characters is 11 public static boolean validSSN(String s){ } // checks to see if the digits are in the right place public static boolean isDigit(char c){ } // checks to see if the dashes are in the right place public static boolean isDash(char c){ } } – lawtonhself Apr 21 '15 at 07:03
This is of course the best solution, and I upvoted it, but I doubt that it would be acceptable for @lawtonhself to turn this in for the assignment! – Daniel Nugent Apr 21 '15 at 07:47

score 1 · Answer 2 · edited Aug 25 '17 at 07:31

1

ssn.matches("^(\\d{3}-?\\d{2}-?\\d{4})$");

edited Aug 25 '17 at 07:31

Bugs

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answered Aug 25 '17 at 06:03

user8486398

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score 0 · Answer 3 · edited May 23 '17 at 12:01

Of course using a regex is the way to go, but given that this is an assignment and it sounds like they want you to do it manually, this is probably what they're looking for.

Read this documentation on Character.isDigit()

Read this documentation on String.charAt()

Read about the conditional operator here

import java.util.Scanner;

public class lab14 {

    public static void main(String[] args){
        Scanner SSN = new Scanner(System.in);
        String s = null;
        boolean valid = false;

        System.out.println("Enter a Social Security Number");

        while (valid == false){
          try{
            s = SSN.nextLine();
            valid = true;
          } catch(Exception e){
            System.out.println("No input! Enter a Social Security Number");
          }
        }

        String result = (validSSN(s) ? " is a valid SSN" : " is not a SSN");
        System.out.println(s + result);

    }

    public static boolean validSSN(String str){
      //check length first
      if (str.length() != 11) return false;

      //traverse through each character
      for (int i = 0; i < str.length(); i++){
        if (i <= 2){
          //these must be digits, otherwise return false
          if (!isDigit(str.charAt(i))){
            return false;
          }
        }
        else if (i == 3 || i == 6){
          //these must be dashes, otherwise return false
          if (!isDash(str.charAt(i))){
            return false; 
          }
        }
        else if (i > 6){
          //these must be digits, otherwise return false
          if (!isDigit(str.charAt(i))){
            return false;
          }
        }
      }

      //return true if it didn't error out
      return true;
    }

    public static boolean isDigit(char c){
      return Character.isDigit(c);
    }

    public static boolean isDash(char c){
      return (c == '-');
    }

}

Verifying if an input string is a correct Social Security Number

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