Use the ? quantifier in Java Regular Expressions

In general, the ? quantifier represents 0 or 1 occurrences of the specified pattern. For example - X? means 0 or 1 occurrences of X.

The regex "t.+?m" is used to find the match in the string "tom and tim are best friends" using the ? quantifier.

A program that demonstrates this is given as follows:

Example

 Live Demo

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Demo {
   public static void main(String args[]) {
      Pattern p = Pattern.compile("t.+?m");
      Matcher m = p.matcher("tom and tim are best friends");
      System.out.println("The input string is: tom and tim are best friends");
      System.out.println("The Regex is: t.+?m");
      System.out.println();
      while (m.find()) {
         System.out.println("Match: " + m.group());
      }
   }
}

Output

The input string is: tom and tim are best friends
The Regex is: t.+?m
Match: tom
Match: tim

Now let us understand the above program.

The subsequence “t.+?m” is searched in the string sequence "tom and tim are best friends". The find() method is used to find if the subsequence i.e. t followed by any number of t and ending with m is in the input sequence and the required result is printed.