Regular Expression- Pattern Matching in java

Java provides a package called 'java.util.regex' for pattern matching.

The java.util.regex package has two classes and one exception class, the two classes namely - Pattern and Matcher.

A small example code given below validates the string with the given regular expression.

 import java.util.regex.Matcher;  
 import java.util.regex.Pattern;  
   
 public class Main {  
   public static void main(String[] args) {  
     Pattern pattern = Pattern.compile("\\d*"); //reg exp for 0 or more integers  
     Matcher matcher = null;  
     matcher = pattern.matcher("1111");  
   
     if (matcher.matches()) {  
       System.out.println("Matched");  
     } else {  
       System.out.println("Not Matched");  
     }  
   }  
 }  

Similarly, there are more regular expression format and quantifiers.