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