Regular Expression Metacharacter in 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