Appendix G Elevator Events and Listener Interfaces Outline

Appendix G – Elevator Events and Listener Interfaces Outline G. 1 G. 2 G. 3 G. 4 Introduction Events Listeners Component Diagrams Revisited 2002 Prentice Hall, Inc. All rights reserved.

G. 1 Introduction • Event handling – Object register as “listeners” for events • The class of that object must implement a “listener” interface 2002 Prentice Hall, Inc. All rights reserved.

G. 2 Events • Figures G. 1 -G. 7 contain system events – Each event inherits from class Elevator. Model. Event 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 // Elevator. Model. Event. java // Basic event packet in Elevator simulation package com. deitel. jhtp 4. elevator. event; // Deitel packages import com. deitel. jhtp 4. elevator. model. *; Outline Class Elevator. Model. Event is the superclass for all events in elevator simulation case study public class Elevator. Model. Event { // Location where Elevator. Model. Event was generated private Location location; // source Object that generated Elevator. Model. Event private Object source; // Elevator. Model. Event constructor sets Location public Elevator. Model. Event( Object source, Location { set. Source( source ); set. Location( location ); } // set Elevator. Model. Event Location public void set. Location( Location event. Location ) { location = event. Location; } Location object represents Fig. G. 1 where the event was generated Elevator. Model(i. e. , Floor or Elevator) Event superclass for events in the elevator simulation location ) model. Object object represents the actual Object that Line generated 8 the event Line 11 Line 14 // get Elevator. Model. Event Location public Location get. Location() { return location; } 2002 Prentice Hall, Inc. All rights reserved.

34 35 36 37 38 39 40 41 42 43 44 45 46 } // set Elevator. Model. Event source private void set. Source( Object event. Source ) { source = event. Source; } Outline // get Elevator. Model. Event source public Object get. Source() { return source; } Fig. G. 1 Elevator. Model. Event superclass for events in the elevator simulation model (Part 2). 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 // Bell. Event. java // Indicates that Bell has rung package com. deitel. jhtp 4. elevator. event; Outline // Deitel packages import com. deitel. jhtp 4. elevator. model*; public class Bell. Event extends Elevator. Model. Event { // Bell. Event constructor public Bell. Event( Object source, Location location ) { super( source, location ); } } Bell. Event sent when Bell has rung Fig. G. 2 Bell. Event Elevator. Model. Event subclass indicating that the Bell has rung. Lines 8 -15 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 // Button. Event. java // Indicates that a Button has changed state package com. deitel. jhtp 4. elevator. event; Outline // Deitel packages import com. deitel. jhtp 4. elevator. model. *; public class Button. Event extends Elevator. Model. Event { // Button. Event constructor public Button. Event( Object source, Location location ) { super( source, location ); } } Button. Event sent when Button as been pressed or reset Fig. G. 3 Button. Event Elevator. Model. Event subclass indicating that a Button has changed state. Lines 8 -15 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 // Door. Event. java // Indicates that a Door has changed state package com. deitel. jhtp 4. elevator. event; Outline // Deitel packages import com. deitel. jhtp 4. elevator. model. *; public class Door. Event extends Elevator. Model. Event { // Door. Event constructor public Door. Event( Object source, Location location ) { super( source, location ); } } Door. Event sent when Door has opened or closed Fig. G. 4 Door. Event Elevator. Model. Event subclass indicating that a Door has changed state. Lines 8 -15 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 // Elevator. Move. Event. java // Indicates on which Floor the Elevator arrived or departed package com. deitel. jhtp 4. elevator. event; // Deitel packages import com. deitel. jhtp 4. elevator. model. *; Outline Elevator. Move. Event sent when Elevator arrives at or departs from Floor public class Elevator. Move. Event extends Elevator. Model. Event { // Elevator. Move. Event constructor public Elevator. Move. Event( Object source, Location location ) { super( source, location ); } } Fig. G. 5 Elevator. Move. Event Elevator. Model. Event subclass indicating on which Floor the Elevator has either arrived or departed. Lines 8 -15 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 // Light. Event. java // Indicates on which Floor the Light has changed state package com. deitel. jhtp 4. elevator. event; Outline // Deitel packages import com. deitel. jhtp 4. elevator. model. *; public class Light. Event extends Elevator. Model. Event { // Light. Event constructor public Light. Event( Object source, Location location ) { super( source, location ); } } Light. Event sent when Light has been turned on or off Fig. G. 6 Light. Event Elevator. Model. Event subclass indicating on which Floor the Light has changed state. Lines 8 -15 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 // Person. Move. Event. java // Indicates that a Person has moved package com. deitel. jhtp 4. elevator. event; // Deitel packages import com. deitel. jhtp 4. elevator. model. *; public class Person. Move. Event extends Elevator. Model. Event { // identifier of Person sending Event private int ID; // Person. Move. Event constructor public Person. Move. Event( Object source, Location location, int identifier ) { super( source, location ); ID = identifier; } // return identifier public int get. ID() { return( ID ); } Outline Person. Move. Event sent when Person performs an action in simulation Fig. G. 7 ID for identifying the Person. Move. Event Person that sent the event Elevator. Model. Event subclass indicating that a Person has moved. Lines 8 -26 Line 11 } 2002 Prentice Hall, Inc. All rights reserved.

G. 3 Listeners • Figures G. 8 -G. 14 contain listener interfaces – Interface methods receive as arguments various events 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 Outline // Bell. Listener. java // Method invoked when Bell has rung package com. deitel. jhtp 4. elevator. event; public interface Bell. Listener { // invoked when Bell has rung public void bell. Rang( Bell. Event bell. Event ); } Method invoked when Bell has rung Fig. G. 8 Interface Bell. Listener method when Bell has rung. Line 8 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 // Button. Listener. java // Methods invoked when Button has been either pressed or reset package com. deitel. jhtp 4. elevator. event; Outline public interface Button. Listener { // invoked when Button has been pressed public void button. Pressed( Button. Event button. Event ); // invoked when Button has been reset public void button. Reset( Button. Event button. Event ); } Methods invoked Fig. G. 9 Interface when Button has Button. Listener been pressed or reset methods when Button has been either pressed or reset. Lines 8 -11 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 // Door. Listener. java // Methods invoked when Door has either opened or closed package com. deitel. jhtp 4. elevator. event; Outline public interface Door. Listener { // invoked when Door has opened public void door. Opened( Door. Event door. Event ); // invoked when Door has closed public void door. Closed( Door. Event door. Event ); } Methods invoked when Door been Interface Fig. has G. 10 opened. Door. Listener or closed methods when Door has either opened or closed. Lines 8 -11 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 // Elevator. Move. Listener. java // Methods invoked when Elevator has either departed or arrived package com. deitel. jhtp 4. elevator. event; Outline public interface Elevator. Move. Listener { // invoked when Elevator has departed public void elevator. Departed( Elevator. Move. Event move. Event ); // invoked when Elevator has arrived public void elevator. Arrived( Elevator. Move. Event move. Event ); } Fig. G. 11 Interface Elevator. Move. Methods invoked when methods Listener Elevator has arrived at when Elevator has or departed from a Floor either departed from or arrived on a Floor. Lines 8 -11 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 // Light. Listener. java // Methods invoked when Light has either turned on or off package com. deitel. jhtp 4. elevator. event; Outline public interface Light. Listener { // invoked when Light has turned on public void light. Turned. On( Light. Event light. Event ); // invoked when Light has turned off public void light. Turned. Off( Light. Event light. Event ); } Methods invoked when Light has been turned on or off Fig. G. 12 Interface Light. Listener method for when Light has either turned on or off. Lines 8 -11 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 // Person. Move. Listener. java // Methods invoked when Person moved package com. deitel. jhtp 4. elevator. event; Outline public interface Person. Move. Listener { // invoked when Person has been instantiated in model public void person. Created( Person. Move. Event move. Event ); // invoked when Person arrived at elevator public void person. Arrived( Person. Move. Event move. Event ); // invoked when Person departed from elevator public void person. Departed( Person. Move. Event move. Event ); // invoked when Person pressed Button public void person. Pressed. Button( Person. Move. Event move. Event ); // invoked when Person entered Elevator public void person. Entered( Person. Move. Event move. Event ); // invoked when Person exited simulation public void person. Exited( Person. Move. Event move. Event ); Fig. G. 13 Interface Methods invoked Person. Movewhen Person Listener methods performs an action when Person has moved. Lines 8 -24 } 2002 Prentice Hall, Inc. All rights reserved.

1 2 3 4 5 6 7 8 9 // Elevator. Model. Listener. java // Listener for Elevator. View from Elevator. Model package com. deitel. jhtp 4. elevator. event; Outline // Elevator. Model. Listener inherits all Listener interfaces public interface Elevator. Model. Listener extends Bell. Listener, Button. Listener, Door. Listener, Elevator. Move. Listener, Light. Listener, Person. Move. Listener { } Create interface that extends all listener interfaces Fig. G. 14 Interface Elevator. Model. Listener allows the model to send all events to the view. Lines 6 -9 2002 Prentice Hall, Inc. All rights reserved.

G. 4 Component Diagrams Revisited • Component diagram for events – Components in package event • Each component maps to a class in Figure G. 1 -G. 14 – Elevator. View. java aggregates package event • In Java, class Elevator. View imports package event – Package model aggregates package event • In Java, each class in model imports package event 2002 Prentice Hall, Inc. All rights reserved.

Fig. G. 15 Component Diagram for package event. 2002 Prentice Hall, Inc. All rights reserved.