/*
Date 			: 		12 October 2013
Author			:		Shivam Tiwari [shivamtiwari1011@gmail.com]
Organization		:		http://mycodedock.blogspot.in/
Description		:		http://mycodedock.blogspot.in/2013/10/validating-e-mail-string-java.html
*/
 
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class Main{
	public static void main(String[] args){
 
		//declaring required variables
		String inputString, findPattern;
 
		//creating a new Scanner object
		Scanner scannerObj = new Scanner(System.in);
 
		/*
		Email starts with alpha numeric characters ([_A-Za-z0-9-])
		MAY (optional) have a . followed by alphanumeric characters, underscore & - (\\.[_A-Za-z0-9-] + ) { as in shivam.tiwari93@gmail.com}
		followed by @ and some alphanumeric characters, _ , - @[A-Za-z0-9] { as in @gmail}
		followed by . and some alphanumeric characters only (\\.[A-Za-z0-9]+) { as in .com} 
		MAY have secondary string after . of alphanumeric type only ((\\.[A-Za-z]{2,})) {like .co.in} minimum length is 2
		*/
		findPattern = "^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";
 
		System.out.println("Enter your e-mail id : ");
 
		//get inputString
		inputString = scannerObj.nextLine();
 
		//create a pattern object
		Pattern patternObj = Pattern.compile(findPattern);
 
		//create a matcher object
		Matcher matcherObj = patternObj.matcher(inputString);
 
		if(matcherObj.find()){
			System.out.println("This is a valid e-mail id : " + inputString);
		}
		else{
			System.out.println("This is NOT a valid e-mail id : " + inputString);
		}
	}
}