CSC308 Lecture 15

Software Engineering I
Design Patterns - Singleton
(202302)

Transcript

1. jgs CSC 308 Software Engineering 1 Lecture 15: Design Patterns - Singleton Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu www.javiergs.com Building 14 -227 Office Hours: By appointment
2. jgs Previously …
3. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 3 Project – User create dots
4. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 4 Project – User selects Cluster and clicks Run ✅
5. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 5 Project – User selects Cluster and clicks Run ✅
6. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 6 Project – User selects Line and clicks Run ✅
7. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 7 Project – User selects Line and clicks Run ✅
8. jgs Solution The Programmer Approach
9. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 9 Ideas
10. jgs Solution The Engineer Approach All about modifiability, extensibility, and reuse
11. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 11 Ideas
12. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 12 Think About It Can we do something about that class Repository?
13. jgs Singleton Design Patterns
14. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 14 GoF Patterns
15. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 15 Singleton
16. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 16 class MainApp { public static void Main(String []a){ // Constructor is protected -- cannot use new Singleton s1 = Singleton.getInstance(); Singleton s2 = Singleton.getInstance(); // Test for same instance if (s1 == s2){ // true - Objects are the same instance } } } Singleton
17. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 17 class Singleton{ private static Singleton _instance; // Constructor is 'protected' protected Singleton() {} public static Singleton getInstance(){ if (_instance == null){ _instance = new Singleton(); } return _instance; } } Singleton
18. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 18 Questions
19. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 19 Office Hours Tuesday and Thursday 3 - 5 pm But an appointment required Sent me an email – javiergs@calpoly.edu
20. jgs
21. jgs CSC 308 Software Engineering 1 Lab 15: Design Patterns Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu www.javiergs.com Building 14 -227 Office Hours: By appointment
22. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 22 Ideas Do you Have Questions About Your Assignment 02?
23. jgs CSC 308 Software Engineering I Javier Gonzalez-Sanchez, Ph.D. javiergs@calpoly.edu Winter 2023 Copyright. These slides can only be used as study material for the class CSC308 at Cal Poly. They cannot be distributed or used for another purpose.