// Light.java// Light turns a light on or offpackage com.Anance.elevator.model;// Deitel packagesimport com.Anance.elevator.event.*;public class Light implements ElevatorMoveListener {   // Light state (on/off)   private boolean lightOn;   // time before Light turns off automatically (3 seconds)   public static final int AUTOMATIC_TURNOFF_DELAY = 3000;   // LightListener listens for when Light should turn on/off   private LightListener lightListener;   // location where Light turned on or off   private Location lightLocation;   // set LightListener   public void setLightListener( LightListener listener )   {      lightListener = listener;   }   // turn on Light   public void turnOnLight( Location location )   {      if ( !lightOn ) {         lightOn = true;         // send LightEvent to LightListener         lightListener.lightTurnedOn(             new LightEvent( this, location ) );         lightLocation = location;         // declare Thread that ensures automatic Light turn off         Thread thread = new Thread(             new Runnable() {               public void run()               {                  // turn off Light if on for more than 3 seconds                  try {                     Thread.sleep( AUTOMATIC_TURNOFF_DELAY );                     turnOffLight( lightLocation );                 }                  // handle exception if interrupted                  catch ( InterruptedException exception ) {                     exception.printStackTrace();                  }               }            } // end anonymous inner class         );         thread.start();      }   } // end method turnOnLight   // turn off Light   public void turnOffLight( Location location )   {      if ( lightOn ) {         lightOn = false;         // send LightEvent to LightListener         lightListener.lightTurnedOff(             new LightEvent( this, location ) );      }   } // end method turnOffLight   // return whether Light is on or off   public boolean isLightOn()   {      return lightOn;   }   // invoked when Elevator has departed   public void elevatorDeparted(       ElevatorMoveEvent moveEvent )   {      turnOffLight( moveEvent.getLocation() );   }   // invoked when Elevator has arrived   public void elevatorArrived(       ElevatorMoveEvent moveEvent )   {      turnOnLight( moveEvent.getLocation() );   }}