Regex pattern matching

I am trying to match the following pattern:
TIMEPAST=151:19:15.00
I have tried the following:
Pattern pattern5 = Pattern.compile("(TIMEPAST)=(\\d*:\\d*:\\d*.\\d*)");
This has not worked as well as other patterns I have tried.
Any suggestions greatly appreciated.

Kaj,
My apologies. When I was trying to put together another posting, I discovered that I was using TIMEPAST when I should have been using AVGTIME. When I corrected this, you patterned worked like a charm:
Pattern pattern5 = Pattern.compile("(AVGTIME)=(\\d+:\\d+:\\d+.\\d+)");
Thanks for the help, my hair is gray enough ;-)
Kind Regards,
Bruce

Similar Messages

Help with regex pattern matching.

Hi everyone
I am trying to write a regex that will extract each of the links from a piece of HTML code. The sample piece of HTML is as follows:
<td class="content" valign="top">
     
<script language="JavaScript"
src="http://chat.livechatinc.net/licence/1023687/script.cgi?lang=en&groups=0"></script>
<a href="makeReservation.html">Making a reservation</a><br/>
<a href="changeAccount.html">Changing my account</a><br/>
<a href="viewBooking.html">Viewing my bookings</a><br/>I am interested in extracting each link and the corrresponding text for that link into groups.
So far I have the following regex <td class="content" valign="top">.*?<a href="(.*?)">(.*?)</a><br>However this regex only matches the first line in the block of links, but I need to match each line in the block of links.
Any ideas? Any suggestions are appeciated as always.
Thanks.

Hi sabre,
thanks for the reply.
I am already using a while loop with matcher.find(), but it still only returns the first link based on my regex.
the code is as follows.
private static final Pattern MENU_ITEM_PATTERN = compilePattern("<td class=\"content\" valign=\"top\">.*?<a href=\"(.*?)\">(.*?)</a><br>");
private LinkedHashMap<String,String> findHelpLinks(String body) {
    LinkedHashMap<String, String> helpLinks = new LinkedHashMap<String,String>();
    String link;
    String linkText;
      Matcher matcher = MENU_ITEM_PATTERN.matcher(body);
      while(matcher.find()){
        link = matcher.group(1);
        linkText = matcher.group(2);
        if(link != null && linkText != null){
          helpLinks.put(link,linkText);
    return helpLinks;
private static Pattern compilePattern(String pattern) {
    return Pattern.compile(pattern, Pattern.DOTALL + Pattern.MULTILINE
        + Pattern.CASE_INSENSITIVE);
}Any ideas?

Regex Pattern Match in an extremely long string

I need to search a file containing 1 extremely long line (approximately 1 million characters), The pattern I want to search is "ABC" as long as it appears at least n times whatever user input as n. I need the position of where this pattern is found. How to best do this? I tried to break the input into blocks of 100000 characters at a time as too many characters read cause the 'java out of memory' error to occur.
Then I converted this to a string in order to use REGEX to search. My problem is how to ensure that the last few characters of the current block is also being searched too? How to write the regex expression to do this? Will breaking the input file into multiple lines help?
eg:
Searching for ABC as long as it appears at least 3 times continuously ie (ABCABCABC)
Original Line = XXXXXXXABCABCABCXXXXXXABCX
The first block of 10 characters read is XXXXXXXABCABC
The second block of 10 characters read is ABCXXXXXXABCX
The search result should be position 7 and position 22

If the sequence of characters is longer than a few hundred KB, then turning it into a String requires you to have enough heap space available in the JVM to store the entire String.
If that is a problem, an alternative solution is to have a while loop over an InputStream that reads from the source of characters (a file, a network connection, stdin etc.) and looks for the string. Keep a ring buffer the size of the query string, and read the data from the InputStream into it. Then for each character read, compare the content of the ring buffer to the query string.
This way you will not use more heap space than the size of the query-string, and the size of whatever buffer you use in your InputStream (8KB for the empty constructor of BufferedInputStream at the moment) plus the odds'n ends from the implementation.

RegEx, need help with pattern matching

im going thru a list of Strings...and id like to match some input to it..but the tutorial for regex wont let me find a smaller string within a bigger one if it exists
for example i have a String "java.sun.com" and i want to find "sun" or "java" or "com" or "jav" or ".co"
i think the only way regex will work is if i group the entire thing into
any ideas on how i can manipulate the string into a proper regex pattern so that itll find any of those "searches"
thanks

No, that is not correct. A regex can be constructed to return a match on anything you want. A single character, a newline character, a numeric character and any combination of them. There are limitless possibilities for pattern matching.
See here:
http://java.sun.com/j2se/1.4.1/docs/api/java/util/regex/Pattern.html
Any of the patterns may be compiled into a regex for searching using the matcher.
An alternative is to use the indexOf method of the string class to find what you are looking for.
Example:
String myString = "java.sun.com";
String matchThis = "n.co";
int patternFoundAtThisIndexPosition = myString.indexof(matchThis);patternFoundAtThisIndexPosition will be 7;
or simply:
int index = myString.indexof("sun");index will be 5;

How do you get java regex to match two different pattern

Hi,
I am having trouble getting getting java regex to match two pattern: "unknown host" or "100%".
Here is a snippet of my code:
try{
Process child = Runtime.getRuntime().exec(" perl c:\\ping.pl");
BufferedReader in = new BufferedReader( new InputStreamReader( child.getInputStream() ));
String patternStr = "(unknown host | 100 %)";
Pattern pattern = Pattern.compile(patternStr);
Matcher matcher = pattern.matcher(" ");
String line = null;
while ( (line = in.readLine()) != null){
System.out.println(line);
matcher.reset(line);
if (matcher.find())
// line matches throws pattern
System.out.println("match string");
else
System.out.println("no matches");
I thought the "|" means OR but somehow it is not working.
kirk123

Hi,
with String patternStr = "(unknown host | 100 %)"; you are looking
for the strings "unknown host " OR " 100 %", with the spaces after host and before 100.
Try "(unknown host|100 %)"
hope, this will help you

Regular Expressions (Pattern/Matcher) --- Help

Hi,
I have an regex i.e. Pattern.compile("([0-9])D([0-9])'?(?:([0-9]+)\")?([NSEW])").{code}
It has to exactly match the input e.g *45D15'34"N*
I need to retrieve the values based on grouping.
Group1 = 45 (degree value)
Group2 = 15 (minutes value)
Group3 = 34 (seconds value) ----> this is a non-capturing group
Group4 = N (directions)
The regex works fine for most of longitude/latitude value but I get a StackOverFlow for some. There is a known bug on this http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5050507
According to the bug report, they have said that are many different regex that can trigger the stack overflow....even though the length of my input is not as long as the one posted on the bug report.
I was wondering if anyone could suggest a different way of writing the regex above to avoid the stack over flow.
Thank you in advance

Hi,
I missed the '+' in my original regex Pattern.compile("([0-9]+)D([0-9]+)'?(?:([0-9]+)\")?([NSEW])"){code}.
I have also tried {code} Pattern.compile("(\\d+)D(\\d+)'?(?:(\\d+)\")?([NSEW])");And, the other 2 expressions as suggested by you.
The problem happens when Durham Lat=35D52N Lon=78D47W value is selected from a Jtree(the values are parsed from a xml file to the tree - the xml file has a bout 800 longitude/latitude elements for different cities in the US). It does not happen for other values and If I increment the degree or min by, then the expression works. I am not sure how else i could re-write this exp.
Below is the snippet of the xml file:
<State name="NORTH CAROLINA">
            <City name="Asheville AP"     Lat="35D26'N"     Lon="82D32'W"/>
            <City name="Charlotte AP"     Lat="35D13'N"     Lon="80D56'W"/>
            <City name="Durham"     Lat="35D52'N"     Lon="78D47'W"/>
            <City name="Elizabeth City AP"     Lat="36D16'N"     Lon="76D11'W"/>
            <City name="Fayetteville, Pope AFB" Lat="35D10'N"     Lon="79D01'W"/>
            <City name="Goldsboro,Seymour-Johnson"     Lat="35D20'N"     Lon="77D58'W"/>
            <City name="Greensboro AP (S)"     Lat="36D05'N"     Lon="79D57'W"/>
            <City name="Greenville"     Lat="35D37'N"     Lon="77D25'W"/>
            <City name="Henderson"     Lat="36D22'N"     Lon="78D25'W"/>
            <City name="Hickory"     Lat="35D45'N"     Lon="81D23'W"/>
            <City name="Jacksonville"     Lat="34D50'N"     Lon="77D37'W"/>
            <City name="Lumberton"     Lat="34D37'N"     Lon="79D04'W"/>
            <City name="New Bern AP"     Lat="35D05'N"     Lon="77D03'W"/>
            <City name="Raleigh/Durham AP (S)"     Lat="35D52'N"     Lon="78D47'W"/>
            <City name="Rocky Mount"     Lat="35D58'N"     Lon="77D48'W"/>
            <City name="Wilmington AP"     Lat="34D16'N"     Lon="77D55'W"/>
            <City name="Winston-Salem AP"     Lat="36D08'N"     Lon="80D13'W"/>
        </State>
public final class GeoLine {
    /* Enum for the possible directions of longitude and latitude*/
    public enum Direction {
        N, S, E, W;
        public boolean isLongitude() {
            return (this == E || this == W);
        public boolean isLatitude() {
            return (this == N || this == S);
        public Direction getCanonicalDirection() {
            if (this == S) {
                return Direction.N;
            } else if (this == W) {
                return Direction.E;
            } else {
                return this;
    private final int degree;
    private final int minute;
    private final int second;
    private final Direction dir;
    /* Recognizes longitude and latitude values that has degrees, minutes and seconds i.e. "45D15'34"N
    * or "45D1534"N. The single-quotes for the minutes is optional. And, for the moment we do not support seconds
    * validation although ilog library returns the longitude/latitude with second when NEs and Sub-networks are
    * dragged and dropped on the map.*/
private static final Pattern PATTERN = Pattern.compile("([0-9]+)D([0-9]+)'?(?:([0-9]+)\")?([NSEW])");
    public GeoLine(int degree, int minute, Direction dir) {
        this(degree, minute, 0, dir);
    public GeoLine(int degree, int minute, int second, Direction dir) {
        Log.logInfo(getClass().getSimpleName(), "PAU degree: " + degree + " minute: " + minute + " second: " + second + " direction: " + dir);
        verifyLongitudeLatitude(degree, dir);
        verifyMinute(degree, minute, dir);
        this.degree = degree;
        this.minute = minute;
        this.second = second;
        if (this.degree == 0 && this.minute == 0 && this.second == 0) {
            this.dir = dir.getCanonicalDirection();
        } else {
            this.dir = dir;
    public Direction getDirection() {
        return dir;
    public int getMinute() {
        return minute;
    public int getDegree() {
        return degree;
    public int getSecond() {
        return second;
    public static GeoLine parseLine(String location) {
        * Matcher class will throw java.lang.NullPointerException if a null location
        * is passed, null location validation is not needed.
        Matcher m = PATTERN.matcher(location);
        if(m.matches()) {
            int deg;
            int min;
            int second;
            Direction direction;
            deg = Integer.parseInt(m.group(1));
            min = Integer.parseInt(m.group(2));
            if (m.group(3) == null) {
                second = 0;
            } else {
                second = Integer.parseInt(m.group(3));
            direction = Direction.valueOf(m.group(4));
            return new GeoLine(deg, min, second, direction);
        } else {
            throw new IllegalArgumentException("Invalid location value. Expected format XXDXX'XX\"[NSEW] " + location);
    private void verifyMinute(int deg, int min, Direction direction) {
        /* This validation is to make sure that minute does not exceed 0 if maximum value for latitude == 90
        * or longitude == 180 is specified */
        int maxDeg = direction.isLatitude() ? 90 : 180;
        if(min < 0 || min > 59) {
           throw new NumberFormatException("Minutes is out of range. Value should be less than 60: " + min);
        if (deg == maxDeg && min > 0) {
            throw new NumberFormatException("Degree value " + deg + "D" + direction + " cannot have minute exceeding 0: " + min);
    private void verifyLongitudeLatitude(int valDeg, Direction valDir) {
           int max = valDir.isLatitude() ? 90 : 180;
           if(valDeg < 0 || valDeg > max) {
                throw new NumberFormatException("Degree " + valDeg + valDir + " is invalid");
    public final boolean isLongitude() {
        return dir.isLongitude();
    public final boolean isLatitude() {
        return dir.isLatitude();
    @Override
    public final String toString(){
        if(minute < 10){
            return degree + "D0" + minute + dir;
        } else {
            return degree + "D" + minute + dir;
    @Override
    public boolean equals(Object obj) {
        if (obj instanceof GeoLine) {
            GeoLine other = (GeoLine) obj;
                return (this.degree == other.degree && this.minute == other.minute && this.second == other.second && this.dir == other.dir);
        return false;
    @Override
    public int hashCode() {
        int result = 17;
        result = result * 37 + degree;
        result = result * 37 + minute;
        result = result * 37 + second;
        result = result * 37 + dir.hashCode();
        return result;
}Thank you again.

How to use AND,OR,NOT condition in Pattern Matching in java

how to use AND,OR,NOT condition in Pattern Matching in java
Please anyone give example..

Stop asking these stupid vague questions and do some of your own research.
Start here:
http://www.regular-expressions.info/
http://java.sun.com/j2se/1.5.0/docs/api/java/util/regex/Pattern.html

Pattern matching problme - not getting desired result.

Hi,
According my program , If 'san' is in 'sangeetha', then it should display "hello".
but I am getting only 'hi'
Why ? any idea?
<%@ page import="java.util.regex.Pattern"%>
<%
if(Pattern.matches("san", "sangeetha"))
out.println("hello");
else
out.println("hi");
%>
Result : Hi

sangee wrote:
Hi,
According my program , If 'san' is in 'sangeetha', then it should display "hello".No, that isn't what your patten say. You should read about regular expressions and learn how to use them, or switch to String.indexOf or contains.
Kaj

Pattern matching in String

Hi,
I want to do pattern matching using String. Here is my requirement.
String file_name = (String)hash.get("DOCNAME"));
file_name = file_name.replace("'","285745@");
So, whereever I have '(apostrophe) I will replace it with pattern "285745@" and then at another jsp where I get this request parameter I do reverse as follows:
String docname = (String)request.getParameter("doc_name").replace("285745@","'");
Now I know replace function is not going to do this. It is just a indicative, for you to know what I want to achieve. which other java function / method i can implement to get the desired result.
thanks,
pp

String file_name = (String)hash.get("DOCNAME"));
file_name = file_name.replace("'","285745@");The problem here is that String.replace() operates only on char arguments, you cannot replace entire substrings with it.
The String.replaceAll() method, on the other hand, operates on regular expressions. In many common cases (those in which the substring you want to find contains no characters with special meaning to the regular expression processor) you can use it exactly as you would String.replace() except that it operates on substrings.
But regular expressions are much more powerful than that. The javadoc for the "Pattern" class has some information on how to use them. There is also a tutorial at http://java.sun.com/docs/books/tutorial/extra/regex/intro.html which you might find helpful.
In the 1.4 edition of Java there is no longer any need to screw around with while loops and StringBuffers. Nearly any text processing operation can be done with regular expressions.

Regex not matching an expression

Hello, I've just started using regular expressions and I have a question: I've wanted to create a regex which matches all strings starting with , with the exception that the string --> cannot appear in the middle of the matching text. To do this, I wrote the following pattern:
\Q\E)]*(\Q-->\E)?I'm quite aware that it's a bad idea not telling the regex what to match, but rather what not to match, as it is very vague and probably inefficient, however, I did expect this to work nonetheless, which it just doesn't. It does match the string "\\E)]*(?:(\\Q-->\\E)?+)"Which seemed to work well until I tried the last little sample in the below code:
package net.luke;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class RegexEr {
      * @param args
     public static void main(String[] args) {
          //Starts with  0 or more times, and ends with --> 0 or 1 times.
          String pattern = "\\Q\\E)]*(?:(\\Q-->\\E)?+)";
          String[] searches = new String[] {
                    " you.", "Huh  you say -->?",
                    "I  to  some strings.",
                    "But "};
          Pattern p = Pattern.compile(pattern);
          Matcher m;
          for (int i = 0; i < searches.length; i++) {
               m = p.matcher(searches);
               while (m.find()) {
                    System.out.println(m.group());
Results: 



\\E)]*(\\Q-->\\E)?"Edited by: stevejluke on Jul 23, 2008 8:00 PM

Regular expression and pattern matching/replacing

I have a list of key words. It has around 1000 key word now but can grow to 5000 keywords.
My web application displays lot of texts which are stored in the database. My requirement is to scan each text for the occurance of any of the above keywords. If any keyword is present I have to replace that with some custom values, before showing it to the user.
I was thinking of using using regular expression for replacing the keyword in the text using matcher.replaceAll method as follows:
Pattern pattern = Pattern.compile(patternStr);
Matcher matcher = pattern.matcher(inputStr);
String output = matcher.replaceAll(replacementStr);
But My pattern string will have around 5000 keywords with the 'OR' Logical Operator like- keyword1| keyword2 I keyword3 | ..........
Will such a big pattern string adversly affect the performance? What can I do to speed up the performance? (Since my keyword list is not static i would prefer to do the replacement just before showing the text to the user)
Any suggestions are most welcome.

I don't think a pure regex approach would be that slow, but it would be a maintenance nightmare. I think a combined regex/table-lookup approach would be best: use a regex to identify potential keywords, then look them up in the table to confirm. For instance, to find all Java keywords you could use the regex "\\b[a-z]{2,12}+\\b" to filter out anything that can't possibility be a keyword.
What are you going to replace the keywords with? Will it vary depending on which keyword is found? If so, you'll have to use a table--and you won't be able to use the replaceAll method, because it can't handle dynamically generated replacement values. You would have to use the lower-level appendReplacement and appendTail method instead.

Regex pattern, filter delimiter in sql code

Hi,
The problem I'm having is that the regex pattern below is not catching the beginning "go" and ending "go" of a string.
"(?iu)[(?<=\\s)]\\bgo\\b(?=\\s)"
The idea is catching the "whole word", in this case the word is "go" so if the word is at the beginning of the string or at the end, i still want to include it.
So, for example:
"go select * from table1 go" -> should catch 2 "go"s but catches 0
"go go# select * from table1 --go go" -> should also catch 2 "go"s but catches 0
"go go select * from table1 go go" -> should catch 4 "go"s but catches 2
I have the "[(?<=\\s)]" and the "(?=\\s)" so that the word "go" when next to a special character is not included, for example "--go".
The problem is that this also negates the beginning and ending of the string.
Code to test example: It should split at 1st, 2nd and last "go", but only splits at the 2nd "go".
String s = "go go select * from table1 --go go";
String delimiter = "go";
String[] queries = s.split("(?iu)[(?<=\\s)]\\b" + delimiter + "\\b(?=\\s)");
for (int i = 0; i < queries.length; i++) {
System.out.println(queries[i]);
I really need to fix this but I'm not having much success.
Any help will be appreciated, thanks in advance.

Yes,
I prefer this one: Regex Powertoy (interactive regular expressions)
It's not 100% perfect, but you can see with my example and this online tester that the 1st "go" is not matched. And this is a problem for me.
I want to eliminate the special characters like "#go" or "-go" but i don't want to eliminate the end and start of string.

Pattern matching a string

I'm trying to pattern match a string in java which has the following syntax:
ENSMUS followed by one character which can be anything followed by 11 digits.
I've done this in javascript using the following regex:
var regex = /^ENSMUS(\w{1})(\d{11})$/;I'm slightly confused by the Java equivalent (having looked at the Pattern class in the API). Could anyone lend a hand please?

ENSMUS followed by one character which can be
anything followed by 11 digits.
String s = ...
boolean b = s.matches("ENSMUS.\\d{11}");Note that when matching an entire String, you don't
need to provide a beginning (^) and end ($) in your
regex. Also, you said "any character", this is not
\w, but a . (a period). \w is a "word character".So I assume if it was a word character it would be
String s = ...
boolean b = s.matches("ENSMUS\\w{1}\\d{11}");I'll try it and see what happens. Thanks

Regex to match everything before an underscore

Hi,
I am trying to create a regular expression to match part of a file name into a variable but I can't seem to get it to work correctly.
Here is a sample from gci:
SERVERNAMEAPPUPP01_Baseline20140220.blg
SERVERNAMEWWSCOOE3_Baseline20140220.blg
SERVERNAMEWWSWEB5_Baseline20140220.blg
SERVERNAMEPNWEBWW01_Baseline20140220.blg
SERVERNAMEPNWEBWW02_Baseline20140220.blg
SERVERNAMEPNWEBWW03_Baseline20140220.blg
SERVERNAMEPNWEBWW04_Baseline20140220.blg
SERVERNAMEPNWEBWW05_Baseline20140220.blg
SERVERNAMEPNWEBWW06_Baseline20140220.blg
SERVERNAMEPNWEBWW07_Baseline20140220.blg
SERVERNAMEPNWEBWW08_Baseline20140220.blg
SERVERNAMEPNWEBWW11_Baseline20140220.blg
SERVERNAMEPNWEBWW12_Baseline20140220.blg
SERVERNAMEPNWEBWW17_Baseline.blg
SERVERNAMEPNWEBWW17_Baseline20140220.blg
SERVERNAMEPNWEBWW18_Baseline20140220.blg
SERVERNAMEPNWEBWW22_Baseline20140220.blg
SERVERNAMEPNWEBWW32_Baseline20140220.blg
SERVERNAMEPNWEBWWI01_Baseline20140220.blg
SERVERNAMEPNWEBWWI11_Baseline20140220.blg
LDVWEBWAABEC01_Baseline20140220.blg
LDVWEBWABFEC02_Baseline20140220.blg
What I am attempting to do is match from the start of the file name to the underscore(not including the underscore). This part of the file name contains the server name.
$files = gci E:\CollectedPerfLogs\20140220 -file -name $pattern ='/[^_]*/' foreach ($file in $files){ $file -match $regex $servername = $Matches[0] Write-Host "The server name is $servername" }
The problem is the regexisn't matching even though
I verified it in an online regex tester. I would appreciate any assistance in figuring out why this isn't working.

What's in your $regex variable? That wasn't included in the code you posted. You've also mashed everything onto a single line, which makes it hard to read.
Anyhow, this value for $regex should work with the rest of your code intact:
$regex = '^[^_]+'

Pattern matching regular expressions

I'm attempting to determine if a string matches a pattern of containing less than 100 alphanumeric characters a-z or 0-9 case insensitive. So my regular expression string looks like:
"^[a-zA-Z0-9]{0,100}$"And I use something like...
Pattern pattern = Pattern.compile( regexString );I'd like to modify my regex string to include the email 'at' symbol "@". So that the at symbol will be allowed. But my understanding of regex is very limited. How do I include an "or at symbol" in my regex expression?
Thanks for your help.

* Code by sabre150
private static final Pattern emailMatcher;
    static
        // Build up the regular expression according to RFC821
        // http://www.ietf.org/rfc/rfc0821.txt
        // <x> ::= any one of the 128 ASCII characters (no exceptions)
        String x_ = "\u0000-\u007f";
        // <special> ::= "<" | ">" | "(" | ")" | "[" | "]" | "\" | "."
        //              | "," | ";" | ":" | "@" """ | the control
        //              characters (ASCII codes 0 through 31 inclusive and
        //              127)
        String special_ = "<>()\\[\\]\\\\\\.,;:@\"\u0000-\u001f\u007f";
        // <c> ::= any one of the 128 ASCII characters, but not any
        //             <special> or <SP>
        String c_ = "[" + x_ + "&&" + "[^" + special_ + "]&&[^ ]]";
        // <char> ::= <c> | "\" <x>
        String char_ = "(?:" + c_ + "|\\\\[" + x_ + "])";
        // <string> ::= <char> | <char> <string>
        String string_ = char_ + "+";
        // <dot-string> ::= <string> | <string> "." <dot-string>
        String dot_string_ = string_ + "(?:\\." + string_ + ")*";
        // <q> ::= any one of the 128 ASCII characters except <CR>,
        //               <LF>, quote ("), or backslash (\)
        String q_ = "["+x_+"$$[^\r\n\"\\\\]]";
        // <qtext> ::= "\" <x> | "\" <x> <qtext> | <q> | <q> <qtext>
        String qtext_ = "(?:\\\\[" + x_ + "]|" + q_ + ")+";
        // <quoted-string> ::= """ <qtext> """
        String quoted_string_ = "\"" + qtext_ + "\"";
        // <local-part> ::= <dot-string> | <quoted-string>
        String local_part_ = "(?:(?:" + dot_string_ + ")|(?:" + quoted_string_ + "))";
        // <a> ::= any one of the 52 alphabetic characters A through Z
        //              in upper case and a through z in lower case
        String a_ = "[a-zA-Z]";
        // <d> ::= any one of the ten digits 0 through 9
        String d_ = "[0-9]";
        // <let-dig> ::= <a> | <d>
        String let_dig_ = "[" + a_ + d_ + "]";
        // <let-dig-hyp> ::= <a> | <d> | "-"
        String let_dig_hyp_ = "[-" + a_ + d_ + "]";
        // <ldh-str> ::= <let-dig-hyp> | <let-dig-hyp> <ldh-str>
        // String ldh_str_ = let_dig_hyp_ + "+";
        // RFC821 looks wrong since the production "<name> ::= <a> <ldh-str> <let-dig>"
        // forces a name to have at least 3 characters and country codes such as
        // uk,ca etc would be illegal! I shall change this to make the
        // second term of <name> optional by make a zero length ldh-str allowable.
        String ldh_str_ = let_dig_hyp_ + "*";
        // <name> ::= <a> <ldh-str> <let-dig>
        String name_ = "(?:" + a_ + ldh_str_ + let_dig_ + ")";
        // <number> ::= <d> | <d> <number>
        String number_ = d_ + "+";
        // <snum> ::= one, two, or three digits representing a decimal
        //              integer value in the range 0 through 255
        String snum_ = "(?:[01]?[0-9]{2}|2[0-4][0-9]|25[0-5])";
        // <dotnum> ::= <snum> "." <snum> "." <snum> "." <snum>
        String dotnum_ = snum_ + "(?:\\." + snum_ + "){3}"; // + Dotted quad
        // <element> ::= <name> | "#" <number> | "[" <dotnum> "]"
        String element_ = "(?:" + name_ + "|#" + number_ + "|\\[" + dotnum_ + "\\])";
        // <domain> ::= <element> | <element> "." <domain>
        String domain_ = element_ + "(?:\\." + element_ + ")*";
        // <mailbox> ::= <local-part> "@" <domain>
        String mailbox_ = local_part_ + "@" + domain_;
        emailMatcher = Pattern.compile(mailbox_);
        System.out.println("Email address regex = " + emailMatcher);
    }Wow. Sheesh, sabre150 that's pretty impressive. I like it for two reasons. First it avoids some false negatives that I would have gotten using the regex I mentioned. Like, [email protected] is a valid email address which my regex pattern has rejected and yours accepts. It's unusual but it's valid. And second I like the way you have compartmentalized each rule so that changes, if any custom changes are desired, are easier to make. Like if I want to specifically aim for a particular domain for whatever reason. And you've commented it so that it is easier to read, for someone like myself who knows almost nothing about regex.
Thanks, Good stuff!

Regex pattern matching

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