1. Lecture #4
Ahmed Safwat
Muhamad Hesham
Abdelrahman Al-Ogail

2.  What about Singleton?
 Call for a new requirement.
 First try implementation.
 Meet today’s pattern.
 Second try implementation.
 Common uses.
 Project Description.
 What’s after all of this?

3. What have we did
till now?

4. You: Dad, I need pocket money.
Dad: *^^%^&@&**&^#&*%&*#%

7. sign in
Offline Available
available busy
away
available
away
Away Busy
busy
All states are connected
to offline via sign out

9. Out of No
Pepsi Money
insert
pepsi > 0 money
eject
pepsi = 0
money
Pepsi Has
Sold Money
order pepsi

10. reach cliff
after a while
Running Idle

11.  I want the enemy turn
crazy when you collect a
gem.
 If you touch the enemy
while it is crazy, you die
and it turns idle again.
 Double crazy enemy
speed by 4 times once.

12. reach cliff
after a while
Running Idle
gem
gem collected
collected
player died
Crazy

13. What do you think we need do
this time ?

14.  Violates Open Closed
Princible.
 Not object oriented.
 Further additions will
cause bugs.
 State transitions are
buried between if-else.

15. Exploring the pattern Let’s Google it!

17. Explaining the pattern Pattern class diagram

19. Pac-Man

20. Keyboard with Shift Key

21. Windows Live Mail (Offline/Online)

22. Pattern’s Challenge Try it yourself
 Strategy/State conflict
 Challenge:
What are the differences between State and
Strategy Pattern?

23. What’s Next Further Reading
 State Pattern: Chapter 10 in Head First
 Strategy Pattern: Chapter 1 in Head First
 GoF: Behavioral Pattern Section
 Section: enhance way of drawing shapes

24. Questions??
mhesham.fcis@gmail.com
Zikas_zak@hotmail.com