CODEWITHSUNDEEP
javaregexvalidation
Vikings Dood
Vikings Dood

Reputation: 51

Validate user input for social security number in Java

I want to validate the format of a social security number when initializing an object or using a setter to change the value of that object after its been made. Obviously this will be done via an if statement and a regex string but I do not know how to make that happen in Java.

I found this expression on a different site:

Regex : ^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$

However i cannot tell if its accurate or not, nor do I understand the syntax to check user input against this.

setSocNum(String x){

if (![regex here]){
System.out.println("please enter a valid social security number")
}
}

I am unable to tell how to check against a regex string. If Someone can help me with the syntax here I could easily adapt it to other parts of the class I am working on. Thanks!

Upvotes: 0

Views: 4600

Answers (3)

Pushpesh Kumar Rajwanshi
Pushpesh Kumar Rajwanshi

Reputation: 18357

You can use Pattern class from java and use its matches method which takes two arguments, first one being the regex that you have mentioned and second argument a string and it returns a boolean value which will tell whether the string matched with the regex or not. Here is a sample code for same,

String input = "somedata";
Pattern.matches("^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$", input);

Your method should look something like this,

public void setSocNum(String x) {

    if (Pattern.matches("^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$", x)) {
        System.out.println("please enter a valid social security number");
    }
    // further logic goes here
}

Creation of Pattern object is heavy, so if you intend to use the code where it gets called many times, you should create it once and re-use and avoid re-creation of it again and again.

Here is the explanation of regex:

^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$
  • ^ - Start of string
  • (?!000|666) - This negative look ahead means, fail the match if the string starts with 000 or 666
  • [0-8] - Then match and consume the next digit if it is in range 0 to 8
  • [0-9]{2} - Then match and consume the next any two digits where [0-9] means any digit which you can also compactly write as \d
  • - - Then followed by a hyphen
  • (?!00) - This negative look ahead rejects the match if the next two digits are 00
  • [0-9]{2} - Then next it matches and consumes any two digits
  • - - Then again followed by a hyphen
  • (?!0000) - This negative look ahead rejects the match if the next four digits are 0000
  • [0-9]{4} - Then next it matches and consumes any four digits
  • $ - End of string

Hope my explanation is clear. Let me know for any queries.

Here is the code I suggested in my comment,

public static Pattern SOCIAL_SECURITY_NUM_PAT = Pattern.compile("^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$");

public static boolean isValidSocialSecurityNumber(String input) {
    return SOCIAL_SECURITY_NUM_PAT.matcher(input).matches();
}

You can place this code in some class like SocialSecurityUtils.java and call it from wherever you want using SocialSecurityUtils.isValidSocialSecurityNumber("socialsecuritynumber")

Upvotes: 4

Eslam Nawara
Eslam Nawara

Reputation: 765

Here's the meaning of this pattern: ^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$

  • (?!000|666): Look ahead in the provided string and ensures that it does not have 000 or 666. If you find those patterns, then fail the match - return invalid input.

  • [0-8][0-9]{2}-: Expects three digits followed by a - where the first one is from a range of 0 to 8, and the other two are from a range of 0 to 9

  • (?!0000) Similar to the first one, look ahead and make sure that this pattern 0000 does not exist otherwise fail the validation

  • [0-9]{4}: Expects four digits from a range of 0 to 9

As for ^ and $, they match the beginning and the end of the string respectively.

Hope that helps.

Upvotes: 2

Dheeraj Goud Puppali
Dheeraj Goud Puppali

Reputation: 77

You can use a Pattern to match the string with regex.

    private static Pattern socSecPattern = Pattern.compile("^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$");

    private void setSocNum(String x){
        if (!socSecPattern.matcher(x).matches()){
            System.out.println("please enter a valid social security number")
        }
    }

It is a good idea to have the Pattern variable as be static since it will be called many times.

Upvotes: 2

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