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2. Assume AddressBook is keeping track of all commands executed earlier
History
Command
execute()
undo()
add(Command)
(a) 1
(b) 0..1
(c) *
(d) 1..*
mul {a|b|c|d}
e.g. mul b
OR tinyurl.com/answerpost

3. OOP: Intermediate Concepts

4. Collaborating objects
Some more rules
How to structure?
Object rules
Collaborating objects
Object structure
Follow a paradigm
OOP 1 2 3 4
1. Abstraction
2. Encapsulation
3. …………..
4. ……………..

6. Student
Book
borrows
Student
Book
borrowed by

7. Where to put return date?
Student
Book
borrows
Where to put return date?

8. Association classes Student Book borrows Student Book borrows Loan
returnDate
Association classes

9. Association classes Student Book borrows Student Book borrows Loan
returnDate
Association classes
Student
Book
Loan
returnDate

10. Student
Book
borrows
Loan
returnDate
Association classes

11. Student
Book
borrows
Loan
returnDate
Association classes

12. Student
Book
borrows
Loan
returnDate
Chapter

13. Student
Book
borrows
Loan
returnDate
Composition
Chapter

14. Shelf
Student
Book
borrows
Loan
returnDate
Composition
Chapter

15. Composition Aggregation
Shelf
Student
Book
borrows
Loan
returnDate
Composition
Chapter
Aggregation

16. Composition Aggregation
Shelf
Book
Composition
Chapter
Aggregation

17. Composition
Aggregation

18. Composition
Aggregation

19. Composition Aggregation
Book
Student
borrows
Loan
returnDate
Chapter
Shelf
Composition
Aggregation

20. Composition Aggregation
Book
Student
borrows
Loan
returnDate
Chapter
Shelf
Composition
Aggregation

21. Where to put total students?
Book
Student
borrows
Loan
returnDate
Chapter
Shelf
Where to put total students?

22. You mean I can say Student.getTotal() ?
Class-level members
Shelf
Student
-totalStudents
+getTotal()
Book
borrows
Loan
returnDate
You mean I can say Student.getTotal() ?
Chapter

23. Class-level members Shelf Student -totalStudents +getTotal() Book
borrows
Loan
returnDate
You mean I can say Student.getTotal() ?
Chapter
OK. Can I say Student.totalStudents ?

24. Class-level members Student -totalStudents +getTotal() Book borrows
Loan
returnDate

25. Class-level members Association classes Composition Aggregation foo
bar()
Association classes
Composition
Aggregation

28. Collaborating objects
How to structure?
Object rules
Collaborating objects
Object structure
Follow a paradigm
OOP 1 2 3 4
1. Abstraction
2. Encapsulation
3. …………..
4. ……………..

30. Can it give the behavior we need?
Is this good to go?
Can it give the object structure we need?
Possibly. It follows the real world.
History
:History
TextUi
MSLogic
Storage
:TextUi
:MSLogic
:Storage
Minefield
:Minefield
m2:Mine
s3:Square
s2:Square
m1:Mine
s1:Square
s4:Square ?
Square
Mine
Can it give the behavior we need?

32. The architect
<iframe width="560" height="315" src="

34. [interactions between components for a given scenario]UI
[interactions between components for a given scenario]
Sequence Diagrams

35. [interactions between components for a given scenario]
:UI
operation
returned value
[interactions between components for a given scenario]
Sequence Diagrams

36. :UI

37. :UI

38. :UI

39. :UI

40. :UI

43. SD for PC phone :PCPhoneUI User press key Shows digit ‘send’
Complete this Sequence diagram. System: PC Phone Actor: phone user MSS: 1. User presses digit 2. System shows digit Repeat step 1-2 until telephone number is entered. 3. User press ‘send’ 4. System connects the call. Telephone conversation takes place. 5. User press ‘end’ 6. System disconnects the call Use case ends.
:PCPhoneUI
User
loop
[Until full number]
press key
Shows digit
‘send’
call connected
‘end’
call disconnected

44. :UI

45. :UI

46. :UI
:MSLogic

47. :UI
:MSLogic

49. I want a foo()
No. That’s against SRP!

53. :UI
:MSLogic

54. :UI
:MSLogic

55. :UI
:MSLogic

56. :UI
:MSLogic
Reference frame

57. :UI
:MSLogic

58. :UI
:MSLogic

59. :MSLogic
:Storage
:History

62. Collaborating objects
How to structure?
Object rules
Collaborating objects
Object structure
Follow a paradigm
OOP
Object behavior 1 2 3 4
1. Abstraction
2. Encapsulation
3. …………..
4. ……………..

63. 76767 OR tinyurl.com/answerpost
Assume you are implementing a minesweeper game. Explain how you would eliminate the possibility of losing the game on the first click.
first {answer}
e.g. first blah blah blah
feed2103 blah blah..
OR tinyurl.com/answerpost

64. * Admin foreach Student s: s.getGPA(); … UGStudent Student NGStudent
PGStudent

65. Inheritence * foreach Student s: s.getGPA(); … :UGStudent UGStudent
Admin
Student
NGStudent
getGPA()
PGStudent

66. Inheritence
is a
UGStudent
Student
NGStudent
getGPA()
PGStudent

67. Inheritence super class : sub class parent class : child class
base class : derived/extended class
UGStudent
Student
NGStudent
getGPA()
PGStudent
specialization
generalization

68. 77577 OR tinyurl.com/answerpost
How many of these show true inheritance?
(d)
(a)
Camera
Cat
Tiger
iPhone
Wheel
Telephone
(b)
Car
Engine
(c)
Novel
TextBook
true {0|1|2|3|4}
e.g. true 3
feed2103 blah blah…
OR tinyurl.com/answerpost

69. Inheritence inheritance tree/hierarchy UGStudent UGStudent Student
NGStudent
NGStudent
NGStudent
getGPA()
PGStudent
PGStudent

70. Java: Single class hierarchy
Object
HelloWorld
Square
FilledSquare …
C++: Many class hierarchies

71. Java: Single class hierarchy
Multiple inheritance
Java: Single class hierarchy
Object
Horse ?
shark
HelloWorld
Square … …
FilledSquare
C++: Many class hierarchies

72. Interface Segregation Principle
No client should be forced to depend on a method it does not use.
Do you show the same personality to all of these?
Parents
Friends
BF/GF
BF/GF
BF/GF
BF/GF

73. Interface Segregation Principle
No client should be forced to depend on a method it does not use.
Do you show the same personality to all of these?
Parents
Friends
BF/GF
BF/GF
BF/GF
BF/GF

74. Interface Segregation Principle
No client should be forced to depend on a method it does not use.
GradeCalculator
Student
getName()
getCAP()
getNationality()
FeeCalculator

75. Interface Segregation Principle <<interface>>
No client should be forced to depend on a method it does not use.
Java allows inheriting from multiple interfaces (but not from multiple classes).
Student
getName()
getCAP()
getNationality()
<<interface>>
Graded
Payee
GradeCalculator
FeeCalculator

76. Interface Segregation Principle <<interface>>
No client should be forced to depend on a method it does not use.
Java allows inheriting from multiple interfaces (but not from multiple classes).
Student
getName()
getCAP()
getNationality()
<<interface>>
Graded
Payee
GradeCalculator
FeeCalculator

77. <<interface>>
interface Graded{
public String getName();
public double getCAP(); }
interface Payee{
public String getNationality();
class Student implements Graded, Payee{
//…
@Override
public String getName(){
return name; }
public String getNationality(){
return nationality;
public double getCAP(){
return cap;
Student
getName()
getCAP()
getNationality()
<<interface>>
Graded
Payee

78. <<interface>>
interface Graded{
public String getName();
public double getCAP(); }
interface Payee{
public String getNationality();
class Student implements Graded, Payee{
//…
@Override
public String getName(){
return name; }
public String getNationality(){
return nationality;
public double getCAP(){
return cap;
Student
getName()
getCAP()
getNationality()
<<interface>>
Graded
Payee

79. <<interface>>
Student ugs = new UGStudent();
GradeCalculator.calculate(ugs);
FeeCalculator.calculate(ugs);
Inheriting from an interface creates an ‘is a’ relationship too.
We can substitute Student objects where Graded interface is expected.
class GradeCalculator{
static void calculate(Graded g){
//... }
Student
getName()
getCAP()
getNationality()
<<interface>>
Graded
Payee
GradeCalculator
FeeCalculator

80. Collaborating objects
How to structure?
Object rules
Collaborating objects
Object structure
Follow a paradigm
OOP
Object behavior 1 2 3 4
1. Abstraction
2. Encapsulation
3. Inheritance
4. ……………..