In this java regex tutorial, we will learn to use regular expressions to test whether a user has entered a valid Social Security number in your application or website form.
Valid SSN Number Format
United States Social Security numbers are nine-digit numbers in the format AAA-GG-SSSS with following rules.
- The first three digits called the area number. The area number cannot be 000, 666, or between 900 and 999.
- Digits four and five are called the group number and range from 01 to 99.
- The last four digits are serial numbers from 0001 to 9999.
To validate all above 3 rules, our regex would be:
Regex : ^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$
Explanation of Regex of Validate SSN
^ # Assert position at the beginning of the string.
(?!000|666) # Assert that neither "000" nor "666" can be matched here.
[0-8] # Match a digit between 0 and 8.
[0-9]{2} # Match a digit, exactly two times.
- # Match a literal "-".
(?!00) # Assert that "00" cannot be matched here.
[0-9]{2} # Match a digit, exactly two times.
- # Match a literal "-".
(?!0000) # Assert that "0000" cannot be matched here.
[0-9]{4} # Match a digit, exactly four times.
$ # Assert position at the end of the string.
Now let’s test our SSN validation regex using some demo SSN numbers.
List<String> ssns = new ArrayList<String>();
//Valid SSNs
ssns.add("123-45-6789");
ssns.add("856-45-6789");
//Invalid SSNs
ssns.add("000-45-6789");
ssns.add("666-45-6789");
ssns.add("901-45-6789");
ssns.add("85-345-6789");
ssns.add("856-453-6789");
ssns.add("856-45-67891");
ssns.add("856-456789");
String regex = "^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$";
Pattern pattern = Pattern.compile(regex);
for (String number : ssns)
{
Matcher matcher = pattern.matcher(number);
System.out.println(matcher.matches());
}
Output:
true
true
false
false
false
false
false
false
false
I will advise to play with above simple regular expression to try more variation.
Happy Learning !!
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