Question

I am looking for the best way in Java to monitor the computer clock (the minutes) and to fire off a method/thread every time it changes.

So if the time is 13:20 and it changes to 13.21 then do something. So any time there is a minute change some code gets fired.

What is the best way to listen to the minute section of the clock for changes ?

Thanks,
Richard

Answer 1

1. Find the current system time using System.currentTimeMillis()
2. Calculate how many milliseconds until the next minute
3. Schedule a TimerTask on a Timer to run in that number of milliseconds in the future

4. In that TimerTask’s event handler schedule a new reoccurring TimerTask to run every 60,000 milliseconds.

   int milisInAMinute = 60000;
   long time = System.currentTimeMillis();
   
   Runnable update = new Runnable() {
       public void run() {
           // Do whatever you want to do when the minute changes
       }
   };
   
   Timer timer = new Timer();
   timer.schedule(new TimerTask() {
       public void run() {
           update.run();
       }
   }, time % milisInAMinute, milisInAMinute);
   
   // This will update for the current minute, it will be updated again in at most one minute.
   update.run();