CODEWITHSUNDEEP
javaregex
user1956909
user1956909

Reputation:

How can i check multiple lines text in java regex?

I want to check multiple lines of text in Java regular expression. But it is always showing false result. Can anyone explain me why?

For example:

11  12
11  12
11  12

For testing those lines, I am using 11 12\r?\n+. It is working fine in rubular regular expression checker but failing in http://www.regexplanet.com/advanced/java/index.html. Another alternatives I tried was (11 12.\r?\n){3,7}, which is working fine in rubular regex check but failed in regexplanet Java. Can anyone tell me how can check this type of regular expression having repeating pattern?

Upvotes: 1

Views: 264

Answers (1)

Tim Pietzcker
Tim Pietzcker

Reputation: 336208

11 12\r?\n+

matches 11 12, followed by an optional carriage return, followed by one or more line feeds (without carriage returns). This is obviously not what you want.

(11 12.\r?\n){3,7}

matches 11 12, followed by one additional character except newlines, followed by an optional CR and a line feed; all of this is repeated 3 to 7 times. So the dot is wrong here. Use this instead:

(11 12\r?\n){3,7}

Finally, be aware that you usually need to double backslashes in a Java regex because of string escaping rules (although in this particular case, you'll be alright because \r and \n happen to work as string escapes, too):

Pattern regex = Pattern.compile("(11 12\r?\n){3,7}");  // works the same as
Pattern regex = Pattern.compile("(11 12\\r?\\n){3,7}");

Upvotes: 2

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