title: Louse coupling and java buttons
body: <p>I am reading a book and it gives an example on loose coupling:</p>
  
  <blockquote>
    <p>As an example take Javas buttons, where you take and assign a button
    listener to the buttons of the existing type without having to change
    anything in the existing button class.</p>
  </blockquote>
  
  <p>I am not sure I understand what the author means. How is that an example of loose coupling?</p>