Check if a string only contains letters - Email Validation

Question

I'm new to Android developing. In my login authentication activity, I want validation for input fields. I want the characters after "." to be letters only.

ehsan@gmail. com

If user typed a String like this: ehsan@gmail.23 return false and make a Toast. my code is:

String email = "ehsan@gmail.com";
String[] ar = email.split(".");

    if ( !ar[ar.length -1].matches("[a-z]") ){
        Toast.makeText(getApplicationContext(), "your email is invalid", Toast.LENGTH_LONG).show();
return false; }

When I run this code, the app force closes. What is wrong?

Answer 1

Please use the Patterns class to validate the email address:

public static boolean isValidEmail(String email) {
    return !TextUtils.isEmpty(email) && Patterns.EMAIL_ADDRESS.matcher(email).matches();
}

Answer 2

I'm not complitely sure, but I suppose that problem is character @, its not in az interval. Hence, try

!ar[ar.length -1].matches("[a-z@]")

Also, keep in mind that e-mail could contain other special characters as '_' for example

Answer 3

email.matches(".+\\\\.[a-zA-Z]+") seems to do the job. It's not the most sophisticated regex in the world, but it works.

valid@gmail.com matches. invalid@gmail.a1b doesn't match.