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• WHEN IS A REGULAR EXPRESSION NOT A REGULAR EXPRESSION CODE

WHEN IS A REGULAR EXPRESSION NOT A REGULAR EXPRESSION CODE

So if your requirement is just to check if the input String matches with the pattern, you should save time and lines of code by using simple String matches method. ("Using Pattern matches method: "+Pattern.matches(".bb", str)) ("Using String matches method: "+str.matches(".bb")) So below code works fine for matching input String with a regular expression in Java. Pattern class also contains matches method that takes regex and input String as argument and return boolean result after matching them. Internally it uses Pattern and Matcher java regex classes to do the processing but obviously it reduces the code lines. Since java regular expression revolves around String, String class has been extended in Java 1.4 to provide a matches method that does regex pattern matching. When we run this java regex example program, we get below output.Įxception in thread "main" 圎xception: Dangling meta character '*' near index 0Īt .error(Pattern.java:1924)Īt .sequence(Pattern.java:2090)Īt .expr(Pattern.java:1964)Īt .compile(Pattern.java:1665)Īt .(Pattern.java:1337)Īt .compile(Pattern.java:1022)Īt .main(PatternExample.java:13) ("Input String matches regex - "+matcher.matches()) Matcher matcher = pattern.matcher("MxxY") Let’s have a look at Java Regex example program. PatternSynta圎xception: PatternSynta圎xception is thrown if the regular expression syntax is not correct.We then use matches method that returns boolean result based on input String matches the regex pattern or not. Matcher class doesn’t have any public constructor and we get a Matcher object using pattern object matcher method that takes the input String as argument. Matcher: Matcher is the java regex engine object that matches the input String pattern with the pattern object created.

Pattern class doesn’t have any public constructor and we use it’s public static method compile to create the pattern object by passing regular expression argument.

Regular Expression can be used to search, edit or manipulate text. The regular expression in java defines a pattern for a String.