The character classes in Java regular expression is defined using the square brackets "[ ]", the character class matches a single character from the specified or, set of possible characters.For example, the regular expression [abc] matches a single character a or, b or, c. Similarly, "[a-z]" matches a character from ... Read More

There are 7 common non printable characters used in general and each character has its own hexadecimal representation.NamecharactersHexa-decimal representationbell\a0x07Escape\e0x1BForm feed\f0x0CLine feed0x0ACarriage return\r0X0DHorizontal tab\t0X09Vertical tab\v0X0BExample 1 Live DemoFollowing Java program accepts an input text and counts the number of tab spaces in it −import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample1 ... Read More

The Possessive Quantifier [X?+] matches the X present once or not present at all.Example Live Demopackage com.tutorialspoint; import java.util.regex.Matcher; import java.util.regex.Pattern; public class PossesiveQuantifierDemo {    private static final String REGEX = "T?+";    private static final String INPUT = "abcdTatW";    public static void main(String[] args) {       ... Read More

You can treat multiple characters as a single unit by capturing them as groups. You just need to place these characters inside a set of parentheses.You can count the number of groups in the current match using the groupCount() method of the Matcher class. This method calculates the number of ... Read More

Greedy quantifiers are the default quantifiers. A greedy quantifier matches as much as possible from the input string (longest match possible) if match not occurred it leaves the last character and matches again.Whereas a reluctant or, non-greedy quantifier matches as little as possible, initially the non-greedy quantifier matches the first ... Read More

Greedy quantifiers are the default quantifiers. A greedy quantifier matches as much as possible from the input string (longest match possible) if match not occurred it leaves the last character and matches again.A possessive quantifier is similar to a greedy quantifier the only difference is it tries to match as ... Read More

The regular expression "(?digit(?!\d)" matches the digit specified.The replaceAll() method accepts two strings: a regular expression pattern and, the replacement string and replaces the pattern with the specified string.Therefore, to remove all numbers in a string except 1 and 2, replace the regular expressions 1 and 2 with one and ... Read More

You can subtract one range from other and use it as new range. You can achieve this by using two variants of character classes i.e. negation and intersection.For example the intersection of ranges [a-l] and [^e-h] gives you the characters a to l as rage subtracting the characters [e-h]Example Live Demoimport ... Read More

The character classes in Java regular expression is defined using the square brackets "[ ]", this subexpression matches a single character from the specified or, set of possible characters. For example the regular expression [abc] matches a single character a or, b or, c.The intersection variant of the character class ... Read More

The java.util.regex.MatcheResult interface provides methods to retrieve the results of a match.You can get an object of this interface using the toMatchResult() method of the Matcher class. This method returns a MatchResult object which represents the match state of the current matcher.The group() method of this interface returns a string ... Read More