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POHow would you use a regular expression to ignore strings that contain a specific substring?
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  1. POHow would you use a regular expression to ignore strings that contain a specific substring?
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    copied!<p>How would I go about using a negative lookbehind(or any other method) regular expression to ignore strings that contains a specific substring?</p> <p>I've read two previous stackoverflow questions:<br> <a href="https://stackoverflow.com/questions/367862/java-regexp-for-file-filtering">java-regexp-for-file-filtering</a><br> <a href="https://stackoverflow.com/questions/42990/regex-to-match-against-something-that-is-not-a-specific-substring">regex-to-match-against-something-that-is-not-a-specific-substring</a><br></p> <p>They are <em>nearly</em> what I want... my problem is the string doesn't end with what I want to ignore. If it did this would not be a problem.</p> <p>I have a feeling this has to do with the fact that lookarounds are zero-width and something is matching on the second pass through the string... but, I'm none too sure of the internals.</p> <p>Anyway, if anyone is willing to take the time and explain it I will greatly appreciate it.</p> <p>Here is an example of an input string that I want to ignore:</p> <p>192.168.1.10 - - [08/Feb/2009:16:33:54 -0800] "GET /FOO/BAR/ HTTP/1.1" 200 2246</p> <p>Here is an example of an input string that I want to keep for further evaluation:</p> <p>192.168.1.10 - - [08/Feb/2009:16:33:54 -0800] "GET /FOO/BAR/content.js HTTP/1.1" 200 2246</p> <p>The key for me is that I want to ignore any HTTP GET that is going after a document root default page.</p> <p>Following is my little test harness and the best RegEx I've come up with so far.</p> <pre><code>public static void main(String[] args){ String inString = "192.168.1.10 - - [08/Feb/2009:16:33:54 -0800] \"GET /FOO/BAR/ HTTP/1.1\" 200 2246"; //String inString = "192.168.1.10 - - [08/Feb/2009:16:33:54 -0800] \"GET /FOO/BAR/content.js HTTP/1.1\" 200 2246"; //String inString = "192.168.1.10 - - [08/Feb/2009:16:33:54 -0800] \"GET /FOO/BAR/content.js HTTP/"; // This works //String inString = "192.168.1.10 - - [08/Feb/2009:16:33:54 -0800] \"GET /FOO/BAR/ HTTP/"; // This works String inRegEx = "^.*(?:GET).*$(?&lt;!.?/ HTTP/)"; try { Pattern pattern = Pattern.compile(inRegEx); Matcher matcher = pattern.matcher(inString); if (matcher.find()) { System.out.printf("I found the text \"%s\" starting at " + "index %d and ending at index %d.%n", matcher.group(), matcher.start(), matcher.end()); } else { System.out.printf("No match found.%n"); } } catch (PatternSyntaxException pse) { System.out.println("Invalid RegEx: " + inRegEx); pse.printStackTrace(); } } </code></pre>
 

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