How to validate multiple email addresses with regular expression in Java

In this example I have demonstrated the use of the regular expressions in Java programming language to do a validation of the email address. The email address might be just one or multiples selected by a semi colon or a comma. I also have presented numerous test cases of the email addresses and then have finally provided the output of running the program, as usual.

package com.icodejava.tools;

/**
 * @author Kushal Paudyal
 * Last Modified on 2011/05/11
 * 
 * This class demonstrates the use of regular expressions to validate multiple email
 * addresses. Several test examples of the email addresses are also provided.
 * 
 * www.icodejava.com
 */
import java.util.regex.Pattern;

public class RegexMultipleEmailAddressValidation {
	/**
	 * Define a regular expression to validate multiple email addresses.
	 * I think the following expression is more complex that it has to be.
	 * We can think of refactoring it at some later point. But it works 
	 * just fine right now.
	 */
	public static String regex = 
		"(([A-Za-z0-9_\\-\\.])+\\@([A-Za-z0-9_\\-\\.])+\\.([A-Za-z]{2,4}))(((;|,|; | ;| ; | , | ,){1}"
		+"([A-Za-z0-9_\\-\\.])+\\@([A-Za-z0-9_\\-\\.])+\\.([A-Za-z]{2,4}))*)";

	public static void main(String[] args) {
		/**
		 * Validate various email addresses
		 */
		isValid("billgates@badmicrosoft.com");
		isValid("billgates@nation.wide.com");
		isValid("123@badmicrosoft.com");
		isValid("'billgates@badmicrosoft.com'");
		isValid("billgates@badmicrosoft.123");
		isValid("abc.def@badmicrosoft.com");
		isValid("abc.\\def@badmicrosoft.com");
		isValid("abc_def@badmicrosoft.com");
		isValid("abc_def.@badmicrosoft.com");
		isValid("abc_def-@badmicrosoft.com");
		isValid("^billgates@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com;noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com,noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com;;noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com;,noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com; noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com ; noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com , noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com,,noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.com  noreply@badmicrosoft.com");
		isValid("billgates@badmicrosoft.verybad@microsoft.com");

	}

	/**
	 * @param email - The Email Address to be validated
	 * @return true if the email address is valid, else return false.
	 * 
	 * Uses the regular expression defined above to do the validation.
	 */
	public static boolean isValid(String email) {
		System.out.println(email + " >>>>>>>> is Valid? " + Pattern.matches(regex, email));
		return Pattern.matches(regex, email);
	}

}


Here is the output of this program:

billgates@badmicrosoft.com >>>>>>>> is Valid? true
billgates@nation.wide.com >>>>>>>> is Valid? true
123@badmicrosoft.com >>>>>>>> is Valid? true
'billgates@badmicrosoft.com' >>>>>>>> is Valid? false
billgates@badmicrosoft.123 >>>>>>>> is Valid? false
abc.def@badmicrosoft.com >>>>>>>> is Valid? true
abc.\def@badmicrosoft.com >>>>>>>> is Valid? false
abc_def@badmicrosoft.com >>>>>>>> is Valid? true
abc_def.@badmicrosoft.com >>>>>>>> is Valid? true
abc_def-@badmicrosoft.com >>>>>>>> is Valid? true
^billgates@badmicrosoft.com >>>>>>>> is Valid? false
billgates@badmicrosoft.com;noreply@badmicrosoft.com >>>>>>>> is Valid? true
billgates@badmicrosoft.com,noreply@badmicrosoft.com >>>>>>>> is Valid? true
billgates@badmicrosoft.com;;noreply@badmicrosoft.com >>>>>>>> is Valid? false
billgates@badmicrosoft.com;,noreply@badmicrosoft.com >>>>>>>> is Valid? false
billgates@badmicrosoft.com; noreply@badmicrosoft.com >>>>>>>> is Valid? true
billgates@badmicrosoft.com ; noreply@badmicrosoft.com >>>>>>>> is Valid? true
billgates@badmicrosoft.com , noreply@badmicrosoft.com >>>>>>>> is Valid? true
billgates@badmicrosoft.com,,noreply@badmicrosoft.com >>>>>>>> is Valid? false
billgates@badmicrosoft.com  noreply@badmicrosoft.com >>>>>>>> is Valid? false
billgates@badmicrosoft.verybad@microsoft.com >>>>>>>> is Valid? false

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One Response to How to validate date in Java using Regular Expressions

  1. sdfqsdf says:

    thanks, it works like a charm

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