CODEWITHSUNDEEP
javaregex
diazazar
diazazar

Reputation: 542

Regular expression to remove everything but a specific format

I have a text like this:

ASD.123.av.234.X_975.dfgdfg

and i wish to round it up to:

.123.234.

 "\\.[0-9]+\\."

this represents my current pattern to select the .number. but negative lookahead didnt work for me: "(?!^\\.[0-9]+\\.)" do you guys have any ideea how to achieve this?

Upvotes: 0

Views: 109

Answers (4)

Braj
Braj

Reputation: 46841

Simply try with Lookaround to select the .number.

The lookaround actually matches characters, but then gives up the match, returning only the result: match or no match

(?<=\.)\d+(?=\.)

Online demo

Pattern explanation:

  (?<=                     look behind to see if there is:
    \.                       '.'
  )                        end of look-behind
  \d+                      digits (0-9) (1 or more times)
  (?=                      look ahead to see if there is:
    \.                       '.'
  )                        end of look-ahead

Sample code:

String str = "ASD.123.av.234.X_975.dfgdfg";
Pattern p = Pattern.compile("(?<=\\.)\\d+(?=\\.)");
Matcher m = p.matcher(str);
while (m.find()) {
    System.out.println(m.group());
}

output:

123
234

What is meaning of your regex pattern?

  (?!                      look ahead to see if there is not: 
    ^                        the beginning of the string
    \.                       '.'
    [0-9]+                   any character of: '0' to '9' (1 or more times )
     \.                       '.'
   )                        end of look-ahead

The problem is with ^ that asserts the beginning of the string.

Upvotes: 1

Michał Schielmann
Michał Schielmann

Reputation: 1382

Try the regex below. It would get you all groups of .number.. You would have to yoin the nymbers later though.

(\.[0-9]+\.)+

Try this site for further tests: http://www.regexplanet.com/advanced/java/index.html

Upvotes: 0

Tim Zimmermann
Tim Zimmermann

Reputation: 6420

Try this regex: (\.[0-9]+?\.)(?:.*?\.([0-9]+?\.))+.

In your output above, you seem to don't want to have .123..234. but .123.234. This regex accomplishes that. It works without lookaheads.

Regex Demo

Upvotes: 0

vks
vks

Reputation: 67968

  (?=.*?\.\d+\..*?).*?(.\d+.).*?

You can try this.It employs positive lookahead.

http://regex101.com/r/dK7kR5/1

Upvotes: 0

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