Matcher usePattern() method in Java with Examples

The java.util.regex.Matcher class represents an engine that performs various match operations. There is no constructor for this class, you can create/obtain an object of this class using the matches() method of the class java.util.regex.Pattern.

The usePattern() method of the Matcher class accepts a Pattern object representing a new regex pattern and uses it to find matches.

Example

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class UsePatternExample {
   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      System.out.println("Enter input text: ");
      String input = sc.nextLine();
      String regex = "[#%&*]";
      //Creating a pattern object
      Pattern pattern = Pattern.compile(regex);
      //Creating a Matcher object
      Matcher matcher = pattern.matcher(input);
      int count =0;
      while(matcher.find()) {
         count++;
      }
      //Retrieving Pattern used
      System.out.println("The are "+count+" special characters [# % & *] in the given text");
      //Building a pattern to accept 5 t 6 characters
      Pattern newPattern = Pattern.compile("\\A(?=\\w{6,15}\\z)");
      //Switching to new pattern
      matcher = matcher.usePattern(newPattern);
      if(matcher.find()) {
         System.out.println("Given input contain 6 to 15 characters");
      } else {
         System.out.println("Given input doesn't contain 6 to 15 characters");
      }
   }
}

Output

Enter input text:
#*mypassword&
The are 3 special characters [# % & *] in the given text
!!mypassword!
Given input doesn't contain 6 to 15 characters