Java How to Program Fourth Edition - DCC

1436 Elevator Model (on CD) Appendix H
(lines 57–65). Line 64 of method doorOpened interrupts the Person’s thread, which
terminates method sleep of line 135. Method interrupt throws an InterruptedException
received by a catch block (lines 147–155). Line 150 of this
catch block unregisters the Person with the Door on the Floor, and line 154 calls
private method enterAndRideElevator (lines 175–214)—however, according to
Fig. 5.29, if the Door on the Floor is already open when the Person arrives, the
Person calls method enterAndRideElevator immediately.
Line 178 of method enterAndRideElevator sends a personEntered event
to personMoveListener, indicating that the Person is entering the Elevator.
When the Person enters the Elevator, the Person’s Location references the Elevator
(lines 181–183). When the Person has entered the Elevator, lines 189–190
register the Person as a DoorListener with the Door in the Elevator. Lines 197–
200 allow the Person to press the Button in the Elevator and to send a person-
PressedButton event to the personMoveListener. Lines 206–207 invoke the
synchronized method ride in the Elevator, ensuring that other Persons cannot
occupy the Elevator. When the Elevator arrives, it sends an elevatorArrived
event to the Door in the Elevator, which opens that Door and invokes method
doorOpened of the Person. Method doorOpened, as previously mentioned, interrupts
the Person’s thread—in this case, method interrupt terminates the sleep in
method ride and allows the Person to exit the Elevator (allowing a Person waiting
for the Elevator to enter). Method enterAndRideElevator returns, and lines 161–
170 of method run make the Person exit the Elevator and exit the simulation shortly
thereafter.
H.10 Component Diagrams Revisited
In Section 13.17, we introduced the component diagram for the elevator simulation. In our
simulation, the each class in the model imports package event—we showed the components
of package event in Fig. G.15. Figure H.14 presents the component diagram for
package model. Each component in package model maps to a class from the class diagram
of Fig. 15.21—package model aggregates package event.
H.11 Conclusion
This concludes discussion case study model. We hope you have enjoyed the design process
of our elevator simulation using the UML, along with the presentation of object-oriented
fundamentals and Java-specific topics, such as event handling and multithreading. Using
the concepts discussed in this case study, you should now be able to tackle even larger systems.
We encourage you to read Appendix I, which implements the ElevatorView,
which transforms the ElevatorModel that we have designed into a vibrant and interactive
program abundant with graphics, animation and sound.