import java.util.regex.*;

public class ValidateEmail {

    private static Pattern pattern;
    private static Matcher matcher;

    public static void main(String[] args)
    {
        String[] testEmails = { "dean@hotmail.co.uk", "joe.melsha@live.com", "dean_a_g@hotmail.com", "dean..fail@live.com" };
        for (int index = 0; index < testEmails.length; index++)
            System.out.println("Email: " + testEmails[index] + " is " + (validEmail(testEmails[index]) ? "valid." : "invalid."));
    }

    public static boolean validEmail(String address)
    {
        return (matcher = pattern.matcher((CharSequence) address)).matches();
    }

    static {

        String regex = "^[\\w\\-]([\\.\\w])+[\\w]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
        pattern = Pattern.compile(regex, Pattern.CASE_INSENSITIVE);

    }

}