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The Java Developers Almanac 1.4Order this book from Amazon. |
e438. Using a Non-Capturing Group in a Regular ExpressionBy default, a group captures text (see e436 Capturing Text in a Group in a Regular Expression). In some cases, a group is needed but there is no need to capture the text. A non-capturing group should be used to improve performance. A non-capturing group starts with(?: .
String inputStr = "abbabcd"; String patternStr = "(a(?:b*))+(c*)"; // (?:b*) is a non-capturing group // Compile and use regular expression Pattern pattern = Pattern.compile(patternStr); Matcher matcher = pattern.matcher(inputStr); boolean matchFound = matcher.find(); if (matchFound) { // Get all groups for this match for (int i=0; i<=matcher.groupCount(); i++) { String groupStr = matcher.group(i); } // group 0: abbabc // group 1: ab // group 2: c }
e437. Getting the Indices of a Matching Group in a Regular Expression e439. Using the Captured Text of a Group within a Pattern e440. Using the Captured Text of a Group within a Replacement Pattern
© 2002 Addison-Wesley. |