Java How to Program Fourth Edition - DCC

1408 Elevator Model (on CD) Appendix H
Elevator has departed and invokes method elevatorArrived (lines 137–140)
when the Elevator has arrived. Method elevatorArrived calls method open-
Door—the Door opens when the Elevator has arrived. Method elevatorDeparted
does not perform any action. At a first glance, you may wonder why this method
does not call method closeDoor. The reason is that a Door should close before the
Elevator has departed so the passenger will not be injured—in our model, the Elevator
calls method closeDoor before calling elevatorDeparted.
H.5 Class Button
Buttons (Fig. H.8) are important to the model as well, because they signal the Elevator
to move between Floors. Figure 15.12 indicates that class Button contains boolean
attribute pressed (line 14) to represent the state of the Button (pressed or reset).
Figure 15.12 indicates also that class Button contains methods pressButton (lines
23–29) and resetButton (lines 32–38).
1 // Button.java
2 // Sends ButtonEvents to ButtonListeners when accessed
3 package com.deitel.jhtp4.elevator.model;
4
5 // Deitel packages
6 import com.deitel.jhtp4.elevator.event.*;
7
8 public class Button implements ElevatorMoveListener {
9
10 // ButtonListener
11 private ButtonListener buttonListener = null;
12
13 // represent whether Button is pressed
14 private boolean pressed = false;
15
16 // set listener
17 public void setButtonListener( ButtonListener listener )
18 {
19 buttonListener = listener;
20 }
21
22 // press Button and send ButtonEvent
23 public void pressButton( Location location )
24 {
25 pressed = true;
26
27 buttonListener.buttonPressed(
28 new ButtonEvent( this, location ) );
29 }
30
31 // reset Button and send ButtonEvent
32 public void resetButton( Location location )
33 {
34 pressed = false;
Fig. Fig. Fig. H.8 H.8 H.8 Class Button, which represents a Button in the model, informs listeners
when a Button has been pressed or reset (part 1 of 2).