Email address validation pattern

Question

First off, I'm using JDK 1.4.2_07. What I'm trying to do is validate email addresses with the String.matches(String pattern) function. What I'm having a problem with is coming up with the regex pattern that represents any syntactically valid email address. If someone has a regex pattern that does represent any syntactically valid email address, I would appreciate it if you posted it in a reply to this message. Thanks!
--Ioeth                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Answer 1

Here is the struts implementation of email address validation:
<validator name="email"
classname="org.apache.struts.validator.FieldChecks"
method="validateEmail"
methodParams="java.lang.Object,
org.apache.commons.validator.ValidatorAction,
org.apache.commons.validator.Field,
org.apache.struts.action.ActionErrors,
javax.servlet.http.HttpServletRequest"
depends=""
msg="errors.email">
<javascript><![CDATA[
function validateEmail(form) {
var bValid = true;
var focusField = null;
var i = 0;
var fields = new Array();
oEmail = new email();
for (x in oEmail) {
if ((form[oEmail[x][0]].type == 'text' ||
form[oEmail[x][0]].type == 'textarea') &&
(form[oEmail[x][0]].value.length > 0)) {
if (!checkEmail(form[oEmail[x][0]].value)) {
if (i == 0) {
focusField = form[oEmail[x][0]];
fields[i++] = oEmail[x][1];
bValid = false;
if (fields.length > 0) {
focusField.focus();
alert(fields.join('\n'));
return bValid;
* Reference: Sandeep V. Tamhankar ([email protected]),
* http://javascript.internet.com
function checkEmail(emailStr) {
if (emailStr.length == 0) {
return true;
var emailPat=/^(.+)@(.+)$/;
var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]";
var validChars="\[^\\s" + specialChars + "\]";
var quotedUser="(\"[^\"]*\")";
var ipDomainPat=/^(\d{1,3})[.](\d{1,3})[.](\d{1,3})[.](\d{1,3})$/;
var atom=validChars + '+';
var word="(" + atom + "|" + quotedUser + ")";
var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
var domainPat=new RegExp("^" + atom + "(\\." + atom + ")*$");
var matchArray=emailStr.match(emailPat);
if (matchArray == null) {
return false;
var user=matchArray[1];
var domain=matchArray[2];
if (user.match(userPat) == null) {
return false;
var IPArray = domain.match(ipDomainPat);
if (IPArray != null) {
for (var i = 1; i <= 4; i++) {
if (IPArray[i] > 255) {
return false;
return true;
var domainArray=domain.match(domainPat);
if (domainArray == null) {
return false;
var atomPat=new RegExp(atom,"g");
var domArr=domain.match(atomPat);
var len=domArr.length;
if ((domArr[domArr.length-1].length < 2) ||
(domArr[domArr.length-1].length > 3)) {
return false;
if (len < 2) {
return false;
return true;
}]]>
</javascript>
</validator>