code: public final static boolean isValidEmail(String email) {
          if (email == null) {
              return false;
          } else {
              return android.util.Patterns.EMAIL_ADDRESS.matcher(email).matches();
          }
      }
docs: Uses androids android.util.Patterns.EMAIL_ADDRESS to check if an email address is valid.
  
  @param email Address to check
  @return true if the <code>email</code> is a valid email address.