How to only accept a specific format of numbers from the user in Java?

Question

How can I make it so input from the user will only be accepted if the format is exactly "xxx-xxx-xxxx" where x can be any number, but only numbers, and the dashes have to be there, in those groupings. Basically, it's supposed to accept phone numbers. Right now I have:

Scanner input = new Scanner(System.in);
String in = input.next(); // Stores user input as a string

if (in.contains("[a-zA-Z]") == false && in.length() == 12) {
    System.out.println("Number Accepted");
} else {
    System.out.println("Number Rejected");
}

Currently, it will reject numbers that are greater or less than 12 characters, but it will accept anything that is 12 characters, even if it has letters. I also do not a solution to grouping the numbers with the dashes correctly, as the user should only be able to input 3 numbers, then a dash, then 3 more numbers, then a dash, and then finally 4 numbers.

Are you trying to validate a phone number, an SSN or something entirely different? — Makoto, Apr 20 '15 at 17:38
`String#contains()` accepts char sequence, not a regex. Your method will check occurence of "[a-zA-Z]" substring. — Alex Salauyou, Apr 20 '15 at 17:39
The following regular expression should do the trick: `/^\d{3}-\d{3}-\d{4}$/`. — Mr. Polywhirl, Apr 20 '15 at 17:40
Do you mean `"\\d{3}\\-\\d{3}\\-\\d{4}"`? This doesn't apply to any international number. — Peter Lawrey, Apr 20 '15 at 17:41
@PeterLawrey: No, that is the universal regex. That is up to ***careless_leader*** to figure out. I did not portray it as a string for a reason. — Mr. Polywhirl, Apr 20 '15 at 17:43

score 1 · Answer 1 · answered Apr 20 '15 at 17:42

1

You could use a Pattern to apply a regular expression:

Pattern pattern = Pattern.compile("^\d{3}-\d{3}-\d{4}$");
Scanner input = new Scanner(System.in);
String in = input.next(); // Stores user input as a string

if (pattern.matcher(in).matches())) {
    System.out.println("Number Accepted");
} else {
    System.out.println("Number Rejected");
}

answered Apr 20 '15 at 17:42

Mureinik

297,002
52
306
350

1

There is no need on `^` and `$`: `matches()` checks against entire string opposed to `find()` – Alex Salauyou Apr 20 '15 at 17:44
1

Or just `in.matches(regex)`. – Bubletan Apr 20 '15 at 17:44

How to only accept a specific format of numbers from the user in Java?

1 Answers1