Mine is more simple, I need to validate a domain name: So a domain in its rawest form - not even a subdomain like 4 revised: TLD should actually be labelled "subdomain" as it should include things like uk -- I would imagine the only validation possible (apart from checking against a list) would be 'after the first dot there should be one or more characters under rules #1 Thanks very much, believe me I did try! When it comes to uk, and some Japanese domains, I'm sure you will have to think twice before using regex for that.My personal thought is that regex is not enough to validate a domain to a real-life domain.
There is actually not very much to type and you will get a feel for the rhythm of test first programming.
To run the examples as is, you need an empty directory with the folders folder and make sure your web server can reach these locations.
Finally the underscore is invalid everywhere in all labels.
I know that this is a bit of an old post, but all of the regular expressions here are missing one very important component: the support for IDN domain names. They enable extended UTF-8 characters in domain names.
# Literal https : # Literal : \/ # Literal / \/ # Literal / )?
) # Closes NLA [a-z0-9] # Character class (any of the characters within) [a-z0-9-] # Character class (any of the characters within) (? Implementations of the DNS protocols must not place any restrictions on the labels that can be used.In particular, DNS servers must not refuse to serve a zone because it contains labels that might not be acceptable to some DNS client programs./** * This regular expression allows multiple levels of subdomains followed by a domain and then the tld * This regex will not allow at the beginning of the string * Only uppercase/lowercase alphabets, numbers and hyphen are allowed for subdomain or domain and uppercase/lowercase alphabets, numbers for tld. The tld cannot begin with the number * The length of the domain or subdomain can be between 1 and 63 characters and for tld it can be 2 to 63 characters * Total length of domain name should not exceed 256 characters * * @param domain Name - String value for domain that needs to be validated * @return true if domain name matches with the regex pattern else false */ public static boolean is Valid Domain Name(String domain Name) ^ # Anchors to the beginning to the string. A regular expression for matching valid domain names.