Regular expression “[X?+] ” Metacharacter Java

The Possessive Quantifier [X?+] matches the X present once or not present at all.

Example

 Live Demo

package 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) {       // create a pattern       Pattern pattern = Pattern.compile(REGEX);       // get a matcher object       Matcher matcher = pattern.matcher(INPUT);       while(matcher.find()) {          //Prints the start index of the match.          System.out.println("Match String start(): "+matcher.start());       }    } }

Output

Match String start(): 0 Match String start(): 1 Match String start(): 2 Match String start(): 3 Match String start(): 4 Match String start(): 5 Match String start(): 6 Match String start(): 7 Match String start(): 8