title: How to create a Timer that goes backwards
body: <p>I'm making a Software  by Java (&amp; Netbeans IDE) and one of the features I would like to add is a timer that can be given a certain time (1 hour) and then let it run backwards till it goes <code>00:00:00</code> where it will do a certain action. </p>
  
  <p>I tried to do something with my knowledge of adding a clock to the program but it didn't work. Please help</p>