To realize our countdown mechanism in code, let’s build a
CountDown class that gets initialized with the number of seconds to countdown. This part leads to the following obvious skeleton code:
Next, we need to separate two concerns: the parts dealing with interactive user actions versus the ones that have a reactive nature. We already know how to realize interactive concepts by means of regular methods. In fact, we did so for the timer’s initialization by the definition of a constructor (the method to be called to create a countdown). Besides this, we need a method to start the countdown:
Ignore the “to do” notes for the time ...