Time for action – responding to input

To show the effect of changing the TimeZone, it is necessary to add an hour hand to the clock. When the TimeZone is changed in the drop-down, the hour hand will be updated.

1. Add a zone field to the ClockWidget along with a setter:

   private ZoneId zone = ZoneId.systemDefault();
   public void setZone(ZoneId zone) {
     this.zone = zone;
   }

2. Getters and setters can be generated automatically. Once the field is added, navigate to Source | Generate Getters and Setters. It can be used to generate all missing getters and/or setters; in addition, a single getter/setter can be generated by typing set in the class body, followed by Ctrl + Space (Cmd + Space on macOS).

3. Add an hour hand in the drawClock method using the following:

   e.gc.setBackground(e.display.getSystemColor(SWT.COLOR_BLACK));
   ZonedDateTime now = ZonedDateTime.now(zone);
   int hours = now.getHour();
   arc = (3 - hours) * 30 % 360;
   e.gc.fillArc(e.x, e.y, e.width-1, e.height-1, arc - 5, 10);

4. To update the clock when...