I don’t understand why with this regex the method returns false;
Pattern.matches("\\bi", "an is");
the character i is at a word boundary!
I don’t understand why with this regex the method returns false; Pattern.matches(\\bi, an is);
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I don’t understand why with this regex the method returns false;
Pattern.matches("\\bi", "an is");
the character i is at a word boundary!
In Java,
matchesattempts to match a pattern against the entire string.This is true for
String.matches,Pattern.matchesandMatcher.matches.If you want to check if there’s a match somewhere in a string, you can use
.*\bi.*. In this case, as a Java string literal, it’s".*\\bi.*".java.util.regex.MatcherAPI linksboolean matches(): Attempts to match the entire region against the pattern.What
.*meansAs used here, the dot
.is a regex metacharacter that means (almost) any character.*is a regex metacharacter that means “zero-or-more repetition of”. So for example something likeA.*BmatchesA, followed by zero-or-more of “any” character, followed byB(see on rubular.com).References
Related questions
.*?and.*for regexNote that both the
.and*(as well as other metacharacters) may lose their special meaning depending on where they appear.[.*]is a character class that matches either a literal period.or a literal asterisk*. Preceded by a backslash also escapes metacharacters, soa\.bmatches"a.b".Related problems
Java does not have regex-based
endsWith,startsWith, andcontains. You can still usematchesto accomplish the same things as follows:matches(".*pattern.*")– does it contain a match of the pattern anywhere?matches("pattern.*")– does it start with a match of the pattern?matches(".*pattern")– does it end with a match of the pattern?StringAPI quick cheat sheetHere’s a quick cheat sheet that lists which methods are regex-based and which aren’t:
String replace(char oldChar, char newChar)String replace(CharSequence target, CharSequence replacement)boolean startsWith(String prefix)boolean endsWith(String suffix)boolean contains(CharSequence s)String replaceAll(String regex, String replacement)String replaceFirst(String regex, String replacement)String[] split(String regex)boolean matches(String regex)