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Thread: Regular Expression pattern - complex pattern syntax

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    Default Regular Expression pattern - complex pattern syntax

    I need the regular expression paattern for the following request.

    Source : "abc\\;xysy;xyzablec;yhaxhed\\\\;lkjfsda"

    Pattern : Split the string into arrays by semicolon(;), but the semicolon not followed the slash(\) one or more time.

    Expected output: [bc\\;xysy],[xyzablec],[yhaxhed\\\\;lkjfsda]


    Is this possible, from analyse-- patter executes from left to right, once travels it will never back. Also we can able to union or intersection between the patterens.

    But these topics are not satisfied from my request. Please help me, very urgent


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    Default Re: Regular Expression pattern - complex pattern syntax

    Yes, it is possible. Simply analyze what is needed:

    What can any character before the last one be? Well, it can be any single character except for a semi-colon, or a backslash directly followed by a semi-colon. The pattern then must end with a semi-colon character, or the end of the string. Because these are already consumed in the section before looking for the last character, you don't need to even take it into consideration when writing the pattern for the last character.

    Once you have all the patterns matched, simply trim off the last character if the second to last character isn't a backslash.

    Alternatively, you can leave off any check for what the ending pattern character should be, and instead advance the position to start the next pattern search to include that gap of 1. This removes the need to trim the last "free-standing" semicolon at the end.
    Last edited by helloworld922; June 6th, 2011 at 08:10 AM.

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    Default Re: Regular Expression pattern - complex pattern syntax

    Hello SmartAndy,

    Welcome to the Java Programming Forums.

    Please only post each thread once. I have removed your duplicate thread.

    Regarding your question, take a look at this tutorial: http://www.javaprogrammingforums.com...explained.html

    Other useful links:

    Kvalley's RegEx Creator

    Regular Expression Tester
    Please use [highlight=Java] code [/highlight] tags when posting your code.
    Forum Tip: Add to peoples reputation by clicking the button on their useful posts.

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    Default Re: Regular Expression pattern - complex pattern syntax

    Thank you.

    Ya its possible by using below pattern.
    String[] valueArray= string.split("(?<!\\\\);");

    But i cant understand what this pattern(?<!) explain.. pls help me...

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