Writing Regex in java

Question

I have one string "110:name:name.lastname@provider.com".

I want to create a regex such that the values before first colon should be only numerics i.e. 110, values before second colon should be only alphabets and third part should have a valid email id.

can anyone guide me

valid email id is very wide. What all email ids do you consider valid? — Rohit Jain, Jan 30 '13 at 13:40
why not break it down. e.g. split by ":", length != 3, Bang!, array[0] not number? Bang! array[1] not letters? Bang! array[2] not email? Bang! email regex you could google and pick one. it is always tricky. ^_^ — Kent, Jan 30 '13 at 13:42
See this question for how to validate the email address: http://stackoverflow.com/questions/624581/what-is-the-best-java-email-address-validation-method — wds, Jan 30 '13 at 13:43
spliiting does not seems to be good as i have to write separate regex for all. jgm has given a better solution u can check — user2025528, Jan 31 '13 at 06:42

tckmn · Answer 1 · 2013-01-30T13:50:30.543

I suggest you split it up like this:

String[] tokens = "110:akhil:akhil.mittal@gmail.com".split(":");

Then you will get an array of the items separated by colons.

You can validate the number with this regex:

tokens[0].matches("\\d*");

And the alphabet part with this:

tokens[1].matches("[A-Za-z]*");

You should find an email validator for the last part as regexes are a bad idea for validating emails.

If you really want to use regex for validating emails, use this one (link). Here it is in all its glory below:

(?:(?:\r\n)?[ \t])*(?:(?:(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t]
)+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ \t]))*"(?:(?:
\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(
?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|"(?:[^\"\r\\]|\\.|(?:(?:\r\n)?[ 
\t]))*"(?:(?:\r\n)?[ \t])*))*@(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\0
31]+(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\
](?:(?:\r\n)?[ \t])*)(?:\.(?:(?:\r\n)?[ \t])*(?:[^()<>@,;:\\".\[\] \000-\031]+
(?:(?:(?:\r\n)?[ \t])+|\Z|(?=[\["()<>@,;:\\".\[\]]))|\[([^\[\]\r\\]|\\.)*\](?:
(?:\r\n)?[ \t])*))*|(?:[^()<>@,;:\\".\[\] \000-\031]+(?:(?:(?:\r\n)?[ \t])+|\Z
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score 0 · Accepted Answer · answered Jan 30 '13 at 13:43

0

Three bits there. First and second are easy enough, third one is pretty much impossible with a regex.

Best you will be able to do is something like this:

^[0-9]*:[A-Za-z]*:.*@.*$

You could be a bit more specific than .* for the parts either side of the @ for the email, but frankly the only way you'll really know if an email address is valid is to talk to the mail server for the provided domain and ask.

answered Jan 30 '13 at 13:43

thanks it seems to be a better approach as i dont want to split it in three different strings and write regex for each. for checking the valid email i m using instance of org.apache.commons.validator.EmailValidator. like final EmailValidator emailValidator = EmailValidator.getInstance(); return emailValidator.isValid(value);Can u combine it with above code as i dont use sepate regex for email – user2025528 Jan 31 '13 at 06:39

score 0 · Answer 3 · answered Jan 30 '13 at 13:46

0

similar to jgm's solution, but with the email more specified:

^[0-9]*:[A-Za-z]*:[_A-Za-z0-9-\+]+(\.[_A-Za-z0-9-+]+)*@[A-Za-z0-9-]+(\.[A-Za-z0-9]+)*(\.[A-Za-z]{2,})$

answered Jan 30 '13 at 13:46

roemer

772
5
10

Sorry lots of valid email addresses won't work with that format. The one from Doorknob gives you some idea about how much of a pain it really is to validate email addresses using regexps. – Jan 31 '13 at 08:28

Writing Regex in java

3 Answers3