Bulletproof Android™: Practical Advice for Building Secure Apps

Take 2

If you’re going to create your own login policy you might want to make sure that passwords are a certain length, so in the second example (see Listing 3-4) we’re going to add a minimum password length of six. The code to check the length is straightforward (see line 95). I’ve also added a method, invalidEmail, to make sure that the email address is valid using the following regular expression (see line 78).

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String EMAIL_PATTERN = "^[_A-Za-z0-9-]+(\\.[_A-Za-z0-9-]+)*@[A-Za-z0-9]+(\\.[A-Za-z0-9]+)*(\\.[A-Za-z]{2,})$";

From personal experience I should point out that if you’re writing a method to check emails, or indeed any other authentication, then you should always make the default return what you would expect ...