Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.info o ffi ce: 14 -227 CSC 305 Individual Software Design and Development Lecture 02. Clean Code 

Homework 

Homework: Review Java Read The Java Tutorials (Links available on Canvas) As needed 

Homework: Style Guide Read Java Style Guide https://google.github.io/styleguide/javaguide.html Apply it Always! 

Clean Code 

Summary 6 

Clean Code • Write e ff icient code but prioritize re a d a bility a nd m a int a in a bility. • Optimize perform a nce-critic a l sections only when necess a ry. 7 

Clean Code :: Readability (Easy to read to others) • Single Responsibility Principle (SRP) • Style a nd Comments • Do not Repe a t Yourselves (DRY) • Keep It Simple (KIS) • Dependency Injection (DI) • Error H a ndling 8 

Single Responsibility 

Single Responsibility • E a ch cl a ss or function should h a ve one, a nd only one, job. • Keep functions focused on a single t a sk. • Bre a k down your code into sm a ller, reus a ble modules or functions. • Ensure e a ch module or function h a s a cle a r, well-de f ined purpose. • 10 

Example 11 

Some Ideas. It is NOT a Complete List 12 MOVE EAT SHOW DETECT COLLISION MOVE/ HUNT SHOW SHOW/ CREATE SCORE HANDLING WINNER DETECTOR MOVE/ HUNT 

Tic Tac Toe 13 Main Player Game 

Tic Tac Toe 14 Main Player GameEngine GameBoard 

Tic Tac Toe 15 Driver Player Game public class Driver { public static void main(String[] arg) { Player player = new Player(); Game game = new Game(); game.ready(); do { player.move(); game.move(); } while (!game.isOver()); game.bye(); } } 

Style and Comments 

Consistent Formatting • Follow a consistent code style a nd form a tting guidelines. https://google.github.io/styleguide/javaguide.html • Use indent a tion, whitesp a ce, a nd comments e ff ectively to enh a nce re a d a bility. 17 

Meaningful Names • Use descriptive a nd un a mbiguous n a mes for v a ri a bles, functions, cl a sses, etc. • Avoid using misle a ding or cryptic n a mes. • Follow consistent n a ming conventions. 18 

Commenting and Documentation • Write me a ningful comments th a t expl a in why something is done, not wh a t is done. • Keep comments up to d a te with code ch a nges. • Document public APIs a nd complex logic thoroughly. • Single Line vs Multiple Line ( a nd J a v a Doc) comments 19 

Code 20 https://github.com/CSC3100/App-Paint/ 

Code 21 https://github.com/CSC3100/App-Paint/ 

Code 22 https://github.com/CSC3100/App-Paint/ 

Do not Repeat Yourselves (DRY) 

Don't Repeat Yourself (DRY) • Avoid code duplic a tion by a bstr a cting common function a lity. • Use functions or cl a sses to enc a psul a te repe a ted jobs. 24 

Keep It Simple (KIS) 

Keep It Simple (KIS) • Aim for simplicity in your design a nd implement a tion. • Avoid unnecess a ry complexity or over-engineering. 26 

Code 27 https://github.com/CSC3100/App-Paint/ 

Code 28 https://github.com/CSC3100/App-Paint/ 

Dependency Injection 

Dependency Injection 30 

Dependency Injection • An object’s dependencies (other objects it relies on) a re provided extern a lly r a ther th a n cre a ted intern a lly by the object itself. • Constructor injection: Dependencies a re p a ssed vi a the cl a ss constructor. • Setter injection: Dependencies a re provided through setter methods. • M a ke components more a ccessible to sw a p or extend without modifying the dependent cl a ss. 31 

Tic Tac Toe 32 Main Player Game View 

Dependency Injection 33 public class Driver { public static void main(String[] arg) { View view = new View (); Player player = new Player(view); Game game = new Game(view); game.ready(); do { player.move(); game.move(); } while (!game.isOver()); game.bye(); } } 

Dependency Injection 34 public class Driver { public static void main(String[] arg) { View view = new View (); Player player = new Player(view); Game game = new Game(view); game.ready(); do { player.move(); game.move(); } while (!game.isOver()); game.bye(); } } public class View { public void print(String s) { System.out.println(s); } } public class Game { View myView; public Game(View v) { myView = v; } public void ready() { myView.print (“Welcome!”); } // more code … } 

Questions 35 

Lab 

Second Part | Programming Show me your best Java programming skills by developing the assigned code. I will describe the problem during lecture— attendance is expected and labs are not homework! Team of (max) 2. Individual work is OK 

Second Part | Programming Do not forget: https://google.github.io/styleguide/javaguide.html This is an important part of what I will be grading! 

CSC 305 Individual Software Design and Development Javier Gonzalez-Sanchez, Ph.D. [email protected] Winter 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.