Regular Expression re{ n} Metacharacter in Java

The subexpression/metacharacter “re{ n}” matches exactly n number of occurrences of the preceding expression.

Example 1

import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "to{1}";       String input = "Welcome to Tutorialspoint";       Pattern p = Pattern.compile(regex);       Matcher m = p.matcher(input);       int count = 0;       while(m.find()) {          count++;       }       System.out.println("Number of matches: "+count);    } }

Output

Number of matches: 2

Example 2

Following Java program reads age value from the user it only allows a two-digit number.

import java.util.Scanner; import java.util.regex.Matcher; import java.util.regex.Pattern; public class RegexExample {    public static void main( String args[] ) {       String regex = "\d{2}";       System.out.println("Enter your age:");       Scanner sc = new Scanner(System.in);       String input = sc.nextLine();       Pattern p = Pattern.compile(regex);       Matcher m = p.matcher(input);       if(m.matches()) {          System.out.println("Age value accepted");       } else {          System.out.println("Age value not accepted");       }    } }

Output 1

Enter your age: 25 Age value accepted

Output 2

Enter your age: 2252 Age value not accepted

Output 3

Enter your age: twenty Age value not accepted