Using a Non-Capturing Group in a Regular Expression
By default, a group captures text (see
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
}
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