Java Tutorial/Regular Expressions/Pattern Match

Find the end point of the second "B(ond)"

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class MainClass {
  public static void main(String args[]) {
    Pattern p = Pattern.rupile("B(on)d");
    String candidateString = "My name is Bond. James Bond.";
    String matchHelper[] = { "               ^", "              ^", "                           ^",
        "                          ^" };
    Matcher matcher = p.matcher(candidateString);
    // Find the end point of the second "B(ond)"
    matcher.find();
    int endIndex = matcher.end(0);
    System.out.println(candidateString);
    System.out.println(matchHelper[2] + endIndex);
  }
}

Match Duplicate Words

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
  public static void main(String args[]) throws Exception {
    String duplicatePattern = "\\b(\\w+) \\1\\b";
    Pattern p = Pattern.rupile(duplicatePattern);
    
    int matches = 0;
    String phrase = "this is a test";
    Matcher m = p.matcher(phrase);
    String val = null;
    while (m.find()) {
      val = ":" + m.group() + ":";
      System.out.println(val);
      matches++;
    }
  }
}

Matching Line Boundaries in a Regular Expression

import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
  public static void main(String[] argv) throws Exception {
    CharSequence inputStr = "abc\ndef";
    String patternStr = "abc$";
    // Compile with multiline enabled
    Pattern pattern = Pattern.rupile(patternStr, Pattern.MULTILINE);
    Matcher matcher = pattern.matcher(inputStr);
    boolean matchFound = matcher.find(); // true
    // Use an inline modifier to enable multiline mode
    matchFound = pattern.matches(".*abc$.*", "abc\r\ndef"); // false
    matchFound = pattern.matches("(?m).*abc$.*", "abc\r\ndef"); // true
  }
}

Pattern.matches method

import java.util.regex.Pattern;
public class MainClass {
  public static void main(String args[]) {
    String regex = "ad*";
    String input = "add";
    boolean isMatch = Pattern.matches(regex, input);
    System.out.println(isMatch);
  }
}

Regex for IP v4 Address

/*
 * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/conn/util/InetAddressUtils.java $
 * $Revision: 652020 $
 * $Date: 2008-04-27 22:23:31 +0100 (Sun, 27 Apr 2008) $
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

import java.util.regex.Pattern;
/**
 * A collection of utilities relating to InetAddresses.
 */
public class InetAddressUtils {
    private InetAddressUtils() {
    }
    
    private static final Pattern IPV4_PATTERN = 
        Pattern.rupile(
                "^(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}$");
    private static final Pattern IPV6_STD_PATTERN = 
        Pattern.rupile(
                "^(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$");
    private static final Pattern IPV6_HEX_COMPRESSED_PATTERN = 
        Pattern.rupile(
                "^((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)$");
    public static boolean isIPv4Address(final String input) {
        return IPV4_PATTERN.matcher(input).matches();
    }
    public static boolean isIPv6StdAddress(final String input) {
        return IPV6_STD_PATTERN.matcher(input).matches();
    }
    
    public static boolean isIPv6HexCompressedAddress(final String input) {
        return IPV6_HEX_COMPRESSED_PATTERN.matcher(input).matches();
    }
    
    public static boolean isIPv6Address(final String input) {
        return isIPv6StdAddress(input) || isIPv6HexCompressedAddress(input); 
    }
}

Regex for IP v6 Address

/*
 * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/conn/util/InetAddressUtils.java $
 * $Revision: 652020 $
 * $Date: 2008-04-27 22:23:31 +0100 (Sun, 27 Apr 2008) $
 * 
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

import java.util.regex.Pattern;
/**
 * A collection of utilities relating to InetAddresses.
 */
public class InetAddressUtils {
    private InetAddressUtils() {
    }
    
    private static final Pattern IPV4_PATTERN = 
        Pattern.rupile(
                "^(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)(\\.(25[0-5]|2[0-4]\\d|[0-1]?\\d?\\d)){3}$");
    private static final Pattern IPV6_STD_PATTERN = 
        Pattern.rupile(
                "^(?:[0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$");
    private static final Pattern IPV6_HEX_COMPRESSED_PATTERN = 
        Pattern.rupile(
                "^((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)::((?:[0-9A-Fa-f]{1,4}(?::[0-9A-Fa-f]{1,4})*)?)$");
    public static boolean isIPv4Address(final String input) {
        return IPV4_PATTERN.matcher(input).matches();
    }
    public static boolean isIPv6StdAddress(final String input) {
        return IPV6_STD_PATTERN.matcher(input).matches();
    }
    
    public static boolean isIPv6HexCompressedAddress(final String input) {
        return IPV6_HEX_COMPRESSED_PATTERN.matcher(input).matches();
    }
    
    public static boolean isIPv6Address(final String input) {
        return isIPv6StdAddress(input) || isIPv6HexCompressedAddress(input); 
    }
}

Validate email address

public class Main {
  public static void main(String[] args) {
    System.out.println("isValid = " + isValidEmailAddress("user@domain.ru"));
  }
  static boolean isValidEmailAddress(String email) {
    String EMAIL_REGEX = "^[\\w-_\\.+]*[\\w-_\\.]\\@([\\w]+\\.)+[\\w]+[\\w]$";
    return email.matches(EMAIL_REGEX);
  }
}