How should I validate an e-mail address?

Question

What\'s a good technique for validating an e-mail address (e.g. from a user input field) in Android? org.apache.commons.validator.routines.EmailValidator doesn\'t seem to be

Answer 1

Can I STRONGLY recommend you don't try to 'validate' email addresses, you'll just get yourself into a lot of work for no good reason.

Just make sure what is entered won't break your own code - e.g. no spaces or illegal characters which might cause an Exception.

Anything else will just cause you a lot of work for minimal return...

Answer 2

We have a simple Email pattern matcher now.

Java:

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

Kotlin Function:

 private fun isValidEmail(email: String): Boolean {
        return !TextUtils.isEmpty(email) && Patterns.EMAIL_ADDRESS.matcher(email).matches()
    }

Kotlin Extension:

fun String.isValidEmail() =
    !TextUtils.isEmpty(this) && Patterns.EMAIL_ADDRESS.matcher(this).matches()

Answer 3

Since API 8 (android 2.2) there is a pattern: android.util.Patterns.EMAIL_ADDRESS http://developer.android.com/reference/android/util/Patterns.html

So you can use it to validate yourEmailString:

private boolean isValidEmail(String email) {
    Pattern pattern = Patterns.EMAIL_ADDRESS;
    return pattern.matcher(email).matches();
}

returns true if the email is valid

UPD: This pattern source code is:

public static final Pattern EMAIL_ADDRESS
    = Pattern.compile(
        "[a-zA-Z0-9\\+\\.\\_\\%\\-\\+]{1,256}" +
        "\\@" +
        "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}" +
        "(" +
            "\\." +
            "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,25}" +
        ")+"
    );

refer to: http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.2_r1.1/android/util/Patterns.java

So you can build it yourself for compatibility with API < 8.

Answer 4

There is a Patterns class in package android.util which is beneficial here. Below is the method I always use for validating email and many other stuffs

private boolean isEmailValid(String email) {
    return !TextUtils.isEmpty(email) && Patterns.EMAIL_ADDRESS.matcher(email).matches();
}

Answer 5

Call This Method where you want to validate email ID.

public static boolean isValid(String email)
{
   String expression = "^[\\w\\.-]+@([\\w\\-]+\\.)+[A-Z]{2,4}$";
   CharSequence inputStr = email;
   Pattern pattern = Pattern.compile(expression, Pattern.CASE_INSENSITIVE);
   Matcher matcher = pattern.matcher(inputStr);
   if (matcher.matches()) 
   {
      return true;
   }
   else{
   return false;
   }
}

Answer 6

Here is android.util.Patterns.EMAIL_ADDRESS

[a-zA-Z0-9+._\%-+]{1,256}\@[a-zA-Z0-9][a-zA-Z0-9-]{0,64}(.[a-zA-Z0-9][a-zA-Z0-9-]{0,25})+

String will match it if

Start by 1->256 character in (a-z, A-Z, 0-9, +, ., _, %, - , +)  
then 1 '@' character  
then 1 character in (a-z, A-Z, 0-9)  
then 0->64 character in (a-z, A-Z, 0-9, -)  
then **ONE OR MORE** 
         1 '.' character   
    then 1 character in (a-z, A-Z, 0-9)   
    then 0->25 character in (a-z, A-Z, 0-9, -)

Example some special match email

a@b.c
a+@b-.c
a@b.c.d.e.f.g.h

You may modify this pattern for your case then validate by

fun isValidEmail(email: String): Boolean {
    return Patterns.EMAIL_ADDRESS.matcher(email).matches()
}