1. ECE 264 Object-Oriented Software Development Instructor: Dr. Honggang Wang Spring 2013 Lecture 11: Class diagrams; class relationships

2. Lecture outline Announcements / reminders  Lab 5 has been be posted on Tuesday  Today Review  UML class diagrams  Class relationships  Association, aggregation, and composition  Composition and initialization lists  Modeling in UML Group discussion Example 12/17/2015 ECE 264: Lecture 11 2

3. UML class diagrams UML class diagram contains 3 boxes  First contains class name  Second contains data members  Third contains member functions For member data/functions  Can list names only, but types/arguments preferred Format: name : type Same format for data/functions—type is fn. return type With function arguments, only types needed  + indicates public  - indicates private 12/17/2015 ECE 264: Lecture 11 3

4. Example: Class diagram Point -xCoord: double -yCoord: double +Point() +Point(double, double) +setX(double) : void +setY(double) : void +getX() : double +getY() : double +printPoint(ostream &) : void +movePoint(double, double) : void 12/17/2015 ECE 264: Lecture 11 4

5. Example 2: Time class Time -hours : int -minutes : int +Time() +Time(int, int) +setHours(int) : void +setMinutes(int) : void +getHours() : int +getMinutes() : int -extraF() : int 12/17/2015 ECE 264: Lecture 11 5

6. Example 2: Time.h class Time { public: Time(); Time(int h, int m); void setHours(int newH); void setMinutes(int newM); int getX(); int getY(); private: int hours, minutes; int extraF(); }; 12/17/2015 ECE 264: Lecture 11 6

7. Class relationships Typically have multiple objects in program Different types may interact with one another  Basic interactions: association One class “uses” another in some way Example (from text): ATM “executes” a Withdrawal  Classes as data members: “has a” Two such relationships: aggregation and composition  Difference: are object lifetimes linked?  In composition, if “parent” is destroyed, “child” is as well  Same is not true for aggregation  Can model relationships in UML 12/17/2015 ECE 264: Lecture 11 7

8. Basic UML composition diagram Shows that Rectangle “has a” Point The 1 indicates Rectangle contains 1 point The closed diamond indicates composition  Objects share “life cycle”—destroy rectangle, and you destroy Point 12/17/2015 ECE 264: Lecture 11 8 Rectangle Point 1 -double width -double height -Point origin +Rectangle()+setOrigin() +getHeight()+setWidth() +getOrigin()+move() +getWidth()+area() +setHeight() 1 1

9. Modeling composition/aggregation Composition indicated by solid diamonds attached to association lines  Aggregation would use hollow diamonds Properties  Only one class represents whole  Parts may only belong to one whole at a time 12/17/2015 ECE 264: Lecture 11 9

10. Initialization lists How would we write Rectangle constructor(s)?  Ideally, we’d like to call Point constructor as well  Use an initialization list Explicitly calls constructors for member data Requires parameterized constructor to be defined Can be used for predefined types as well  Example: Rectangle::Rectangle() : height(1), width(1), origin(0,0) {} 12/17/2015 ECE 264: Lecture 11 10

11. Initialization list example Write a parameterized constructor for the Rectangle class that takes 4 arguments:  Height  Width  X coordinate of the origin  Y coordinate of the origin 12/17/2015 ECE 264: Lecture 11 11

12. Example solution Rectangle::Rectangle(double h, double w, double x, double y) : height(h), width(w), origin(x,y) {} 12/17/2015 ECE 264: Lecture 11 12

13. Group Discussion 4 students in a group (team members nearby you) Draw a UML Class Diagram (Three Boxes)  “Person” class What data members? What member functions?  “Events” class What data members? What member functions?  Need a volunteer who presents his/her group discussion results on the blackboard 12/17/2015 ECE 264: Lecture 11 13

14. In-class example This C++ example shows how composition is used as three classes (time, date and event) are used to display the time and day of a particular event. (cited from Prof. G. Blake Stracener's Web) 12/17/2015 ECE 264: Lecture 11 14

15. Time Class /*Specification: This program displays how composition is used. Three classes display the hours, minutes, day, month, year, and name pertaining to an event*/ #include using namespace std; class Time { //Time class public: Time(); Time(int, int); void setTime(int, int); void getTime(int&, int&); void printTime(); void incrementHours(); void incrementMinutes(); private: int hr; int min; }; 12/17/2015 ECE 264: Lecture 11 15

16. Date Class class Date {//Date class public: Date(); Date(int, int, int); void setDate(int, int, int); void getDate(int&, int&, int&); void printDate(); private: int month; int day; int year; }; 12/17/2015 ECE 264: Lecture 11 16

17. Event Class class Event {//Event class public: Event(int hours = 0, int minutes = 0, int m = 1, int d = 1, int y = 1900, string name = "Christmas"); void setEventData(int hours, int minutes, int m, int d, int y, string name); void printEventData(); private: string eventName; Time eventTime; Date eventDay; }; 12/17/2015 ECE 264: Lecture 11 17

18. Main program int main() {//instantiate an object and set data for Christmas Event object; object.setEventData(6, 0, 12, 25, 2010, "Christmas"); //print out the data for object object.printEventData(); //instantiate the second object and set date for the fourth of July Event object2; object2.setEventData(1, 15, 7, 4, 2010, "Fourth of July"); //print out the data for the second object object2.printEventData(); return 0; } 12/17/2015 ECE 264: Lecture 11 18

19. Time.cpp (Time class implementation) Time::Time() { //default constructor hr = 0; min = 0; } Time::Time(int hours, int minutes) { //class time constructor that accepts parameters if(0 <= hours && hours < 24)//makes sure hours are valid hr = hours; else hr = 0; if(0 <= minutes && minutes < 60)//makes sure minutes are valid min = minutes; else min = 0; } 12/17/2015 ECE 264: Lecture 11 19

20. Time.cpp (Time class implementation) void Time::setTime(int hours, int minutes) { //sets a valid time if(0 <= hours && hours < 24) hr = hours; else hr = 0; if(0 <= minutes && minutes < 60) min = minutes; else min = 0; } void Time::getTime(int& hours, int& minutes) { //returns the hours and minutes hr = hours; min = minutes; } 12/17/2015 ECE 264: Lecture 11 20

21. Time.cpp (Time class implementation) void Time::printTime() { //displays the hours and minutes to the screen if(hr < 10) cout << "0"; cout << hr << ":"; if(min < 10) cout << "0"; cout << min << endl; } void Time::incrementHours() { //increments hours by one hr++; if(hr > 23) hr = 0; } 12/17/2015 ECE 264: Lecture 11 21

22. Time.cpp (Time class implementation) void Time::incrementMinutes() { //increments minutes by one min++; if(min > 59) { min = 0; incrementHours(); } 12/17/2015 ECE 264: Lecture 11 22

23. Date.cpp (Date class implementation) Date::Date() { //default constructor month = 1; day = 1; year = 1900; } Date::Date(int m, int d, int y) {//constructor that accepts parameters if(m >= 1 && m <= 12)//makes sure month is valid month = m; else month = 1; if(d >= 1 && d <= 31)//makes sure day is valid day = d; else day = 1; if(y >= 1900 && y <= 2010)//makes sure year is valid year = y; else year = 1900; } 12/17/2015 ECE 264: Lecture 11 23

24. Date.cpp (Date class implementation) void Date::setDate(int m, int d, int y) {//sets a valid date if(m >= 1 && m <= 12) month = m; else month = 1; if(d >= 1 && d <= 31) day = d; else day = 1; if(y >= 1900 && y <= 2010) year = y; else year = 1900; } 12/17/2015 ECE 264: Lecture 11 24

25. Date.cpp (Date class implementation) void Date::getDate(int& m, int& d, int& y) { //returns the month, day and year month = m; day = d; year = y; } void Date::printDate() { //displays the month, day and year to the screen if(month < 10) cout << "0"; cout << month << "/"; if(day < 10) cout << "0"; cout << day << "/"; cout << year; } 12/17/2015 ECE 264: Lecture 11 25

26. Event.cpp (Event class implementation) Event::Event(int hours, int minutes, int m, int d, int y, string name) : eventTime(hours, minutes), eventDay(m, d, y) { eventName = name; } void Event::setEventData(int hours, int minutes, int m, int d, int y, string name) { eventTime.setTime(hours, minutes); eventDay.setDate(m, d, y); eventName = name; } void Event::printEventData() { cout << eventName << " occurs "; eventDay.printDate(); cout << " at "; eventTime.printTime(); cout << endl; } 12/17/2015 ECE 264: Lecture 11 26

27. Final notes Next time  Arrays, vectors, and other container classes  Exam review Acknowledgements: this lecture borrows heavily from lecture slides provided with the following texts: Deitel & Deitel, C++ How to Program, 8 th ed. Etter & Ingber, Engineering Problem Solving with C++, 2 nd ed. 12/17/2015 ECE 264: Lecture 11 27