Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.info o ffi ce: 14 -227 CSC 305 Individual Software Design and Development Lecture 11. Patterns 

✅ Dependencies + Architecture ✅ GUI + Multithreading ✅ Object-Oriented Programming Week 06 2 ✅ Clean Code ✅ Object-Oriented Design 

Running code isn’t enough — design matters This class is about design, not just programming.Being able to compile and run your code is necessary but not sufficient — the focus should be on demonstrating clear design, quality, and adherence to standards. 

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GitHubViz 2.0 5 Size control is managed through the alpha value: with zero lines the display is fully transparent, and as the number of lines increases toward the maximum, the color becomes darker. Complexity is represented by color, determined by the total number of conditional or loop statements (if, switch, while, for). When this total exceeds ten, the color is red; when it is greater than five, the color is yellow; otherwise, it is green. 

UML Cl a ss Di a gr a m 

Standard Solutions Patterns 

De f inition • Design patterns a re solutions to softw a re design problems you f ind a g a in a nd a g a in in re a l-world a pplic a tion development. • P a tterns a re a bout reusable designs a nd inter a ctions between objects. • The 23 G a ng of Four (GoF) patterns a re gener a lly considered the found a tion for a ll other p a tterns (G a mm a , Helm, Johnson, a nd Vlissides). 8 

GoF Patterns 9 

Singleton Pattern 

Singleton 11 

Singleton class MainApp { public static void Main(String []a){ Singleton s1 = Singleton.getInstance(); Singleton s2 = Singleton.getInstance(); // Test for same instance if (s1 == s2){ // true - Objects are the same instance } } } 12 

Singleton class Singleton{ private static Singleton _instance; private Singleton() {} public static Singleton getInstance(){ if (_instance == null){ _instance = new Singleton(); } return _instance; } } 13 

Observer Patterns 

Observer 15 

Classroom | Initial Version 16 https://github.com/CSC3100/Patterns 

Student | Initial Version 17 https://github.com/CSC3100/Patterns 

Teacher | Initial Version 18 https://github.com/CSC3100/Patterns 

Main 

Observer 20 https://github.com/CSC3100/Patterns 

Observable 21 https://github.com/CSC3100/Patterns 

Classroom | New Version 22 https://github.com/CSC3100/Patterns 

Student | New Version 23 https://github.com/CSC3100/Patterns 

Teacher | New Version 24 https://github.com/CSC3100/Patterns 

Important 25 Do not reinvent the wheel! (Do not make another implementation for classes Observer or Observable -they already exist in libraries!) 

Important 26 Depreciated java.util.Observer java.util.Observable The implementation of these packages That is NOT about the Observer pattern being depreciated. 

Important 27 Use java.beans.PropertyChangeListener java.beans.PropertyChangeSupport 

Classroom | Listener Version 28 https://github.com/CSC3100/Patterns 

Student | Listener Version 29 https://github.com/CSC3100/Patterns 

Teacher | Listener Version 30 https://github.com/CSC3100/Patterns 

Thoughts? 31 

Problem 

Problem 33 

Main 34 

DataSource 35 

Panel 36 

Blackboard 37 

Questions 38 

Lab 

Problem 40 

CSC 305 Individual Software Design and Development Javier Gonzalez-Sanchez, Ph.D. [email protected] Fall 2025 Copyright. These slides can only be used as study material for the class CSC305 at Cal Poly. They cannot be distributed or used for another purpose.