Kotlin Standard Library Cookbook

How it works...

Now, let's give it a try and take a look at how we can use the EmailValidator interface in action. Let's assume we have a RegistrationForm class containing a hook method that is invoked every time the input text is modified:

class RegistrationForm() {    fun onInputTextUpdated(text: String) {        // do some actions on text changed    }}

To make use of our EmailValidator interface, we need to declare a class that is implementing it. We can modify the RegistrationForm class to implement the EmailValidator interface:

class RegistrationForm(override var input: String = ""): EmailValidator {    fun onInputTextUpdated(newText: String) {        this.input = newText        if (!isEmailValid()) {            print("Wait! You've entered wrong email...")        } else {            print(