Simple Positive Lookahead : Pattern « Regular Expressions « Java

Simple Positive Lookahead


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

public class Main {
  public static void main(String args[]) {
    String regex = "(?=^255).*";
    Pattern pattern = Pattern.compile(regex);
    String candidate = "";
    Matcher matcher = pattern.matcher(candidate);
    String ip = "not found";
    if (matcher.find())
      ip =;

    String msg = "ip: " + ip;



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