Java Regular Expression : Matcher & Pattern

• Java provides java.util.regex package for regular expression evaluation.
• It has one interface MatchResault and two derived classes Matcher and Pattern.

Testing Matcher and Pattern:-

• The following demo code shows use of Matcher and Pattern class use.It also shows the ISBN code validation.
• A ISBN book code is 13 digit number.

RegularExpressionDemo.java,

package com.sandeep.regular.exp;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegularExpressionDemo {
 
 public static void main(String [] args){
 
 /*matches the input pattern with entire region*/
 Pattern buildPattern = Pattern.compile("p*S");
 Matcher matcher = buildPattern.matcher("pppppS");
 boolean flag = matcher.matches();
 
 System.out.println("Region Matches : "+ flag);
 
 /*replacing first appearnce of p* with 'sandeep' text*/
 Pattern groupPattern = Pattern.compile("p*");
 Matcher stringMatcher = groupPattern.matcher("pppp ter pppp ter pppp abc");
 String modified = stringMatcher.replaceFirst("sandeep");
 
 System.out.println("Modified String: "+modified);
 
 /*A 13 digit ISBN number validation and extraction*/
 Pattern pattern = Pattern.compile("(\d-?){13}");
 Matcher isbnMatcher = pattern.matcher("ISBN: 978-0-12-345678-9");
 while (isbnMatcher.find()){
 System.out.println("ISBN Number is valid and number is : "+isbnMatcher.group());
 }

 }
}

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