what is regex in java code example

Example 1: java regex

import java.util.regex.*;  
public class RegexExample1{  
public static void main(String args[]){  
//1st way  
Pattern p = Pattern.compile(".s");//. represents single character  
Matcher m = p.matcher("as");  
boolean b = m.matches();  
  
//2nd way  
boolean b2=Pattern.compile(".s").matcher("as").matches();  
  
//3rd way  
boolean b3 = Pattern.matches(".s", "as");  
  
System.out.println(b+" "+b2+" "+b3);  
}}

Example 2: regex java

import java.io.*;
import java.util.regex.*;

public class testRegex {

    private static Pattern pattern;
    private static Matcher matcher;

    public static void main(String args[]) {
        pattern = Pattern.compile("Hugo");
        matcher = pattern.matcher("Hugo Etiévant");
        while(matcher.find()) {
            System.out.println("Trouvé !");
        }
    }
}

Example 3: java regex ip

public static boolean isIP(String ip)  {
    Pattern p = Pattern.compile("(([01]?[0-9]{1,2}|2[0-4][0-9]|25[0-5])\\.){3}([01]?[0-9]{1,2}|2[0-4][0-9]|25[0-5])");
    Matcher m = p.matcher(ip);
    return m.matches();
}