1. CSE115: Introduction to Computer Science I Dr. Carl Alphonce 219 Bell Hall 645-4739 alphonce@buffalo.edu 1

3. Agenda Exam reminder –First exam on Wednesday, Sept 28 –Monday Sept 26 is review day (come with questions) –No scheduled recitations next week Last time: –Relationships in model and code first relationship: composition –Lifetime/Scope process memory Today –Brief review –Unified Modeling Language (UML) class diagrams

4. 4 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); }

5. 5 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Class definition is shown in green:

6. 6 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Instance variable name is shown in green:

7. 7 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Instance variable declaration is shown in green:

8. 8 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Access control modifiers are shown in green: Note that access control modifier of _tail is private, not public.

9. 9 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Constructor definition is shown in green:

10. 10 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Header of constructor definition is shown in green:

11. 11 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Access control modifier in header of constructor definition is shown in green:

12. 12 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Name of constructor in header of constructor definition is shown in green:

13. 13 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Parameter list in header of constructor definition is shown in green:

14. 14 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Instantiation of class Tail is shown in green:

15. 15 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } ‘new’ operator in instantiation of class Tail is shown in green:

16. 16 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Use of constructor in instantiation of Tail class is shown in green:

17. 17 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Argument list in instantiation of class Tail is shown in green:

18. 18 Dog – Tail example in Java public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } Assignment of new Tail instance to instance variable is shown in green:

19. UML Unified Modeling Language (Class Diagrams)

20. UML Unified Modeling Language –express design without reference to an implementation language For example

21. Composition in UML

22. Binary Class Relationships: directional binary  two classes are involved – source class has code modification – target class does not composition –source: WHOLE –target: PART in diagram: –line decoration is on source/WHOLE –show only detail that’s needed/desired

23. package cse115; public class Dog { public Dog() { } package cse115; public class Tail { public Tail() { }

24. package cse115; public class Dog { private Tail _tail; public Dog() { _tail = new Tail(); } package cse115; public class Tail { public Tail() { }

25. Questions (from lecture last year) Can you define more than one instance variable in a class definition? Can Dog have a composition relationship with other classes too? ANSWER: Yes! See example on next slide (which shows Dog – Nose composition). Also talked about Dog-Paw composition of cardinality 4.

26. package cse115; public class Dog { private Tail _tail; private Nose _nose; public Dog() { _tail = new Tail(); _nose = new Nose(); } package cse115; public class Tail { public Tail() { }