Java Regular Expressions

import java.util.regex.*;import java.util.*;public class RegexUtils {        // Check if pattern matches    public static boolean matches(String pattern, String input) {        return Pattern.matches(pattern, input);    }        // Find all matches    public static List<String> findAllMatches(String pattern, String input) {        List<String> matches = new ArrayList<>();        Pattern p = Pattern.compile(pattern);        Matcher m = p.matcher(input);        while (m.find()) {            matches.add(m.group());        }        return matches;    }        // Replace all matches    public static String replaceAll(String pattern, String input, String replacement) {        return input.replaceAll(pattern, replacement);    }        // Replace first match    public static String replaceFirst(String pattern, String input, String replacement) {        return input.replaceFirst(pattern, replacement);    }        // Split by pattern    public static String[] split(String pattern, String input) {        return input.split(pattern);    }        // Validate email    public static boolean isValidEmail(String email) {        String pattern = "^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}$";        return Pattern.matches(pattern, email);    }        // Extract groups    public static List<String> extractGroups(String pattern, String input) {        List<String> groups = new ArrayList<>();        Pattern p = Pattern.compile(pattern);        Matcher m = p.matcher(input);        if (m.find()) {            for (int i = 0; i <= m.groupCount(); i++) {                groups.add(m.group(i));            }        }        return groups;    }        // Validate phone number    public static boolean isValidPhone(String phone) {        String pattern = "^\\+?[1-9]\\d{1,14}$";        return Pattern.matches(pattern, phone);    }}

// Simple matchboolean matches = Pattern.matches("\\d+", "123"); // true// Compile pattern for reusePattern pattern = Pattern.compile("\\d+");Matcher matcher = pattern.matcher("abc123def456");// Find all matcheswhile (matcher.find()) {    System.out.println("Found: " + matcher.group());    System.out.println("Start: " + matcher.start());    System.out.println("End: " + matcher.end());}// Replace allString text = "Hello World World";String replaced = text.replaceAll("World", "Java");// Result: "Hello Java Java"// Replace firstString replacedFirst = text.replaceFirst("World", "Java");// Result: "Hello Java World"// Split by patternString input = "one,two,three";String[] parts = input.split(",");// Result: ["one", "two", "three"]// Extract groupsPattern datePattern = Pattern.compile("(\\d{4})-(\\d{2})-(\\d{2})");Matcher dateMatcher = datePattern.matcher("2024-01-15");if (dateMatcher.matches()) {    String year = dateMatcher.group(1);  // "2024"    String month = dateMatcher.group(2); // "01"    String day = dateMatcher.group(3);   // "15"}// Email validationString email = "[email protected]";boolean isValid = email.matches("^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}$");// Find and replace with groupsString text2 = "Hello John, Hello Jane";String result = text2.replaceAll("Hello (\\w+)", "Hi $1");// Result: "Hi John, Hi Jane"