Kotlin from Scratch: A Project-Based Introduction for the Intrepid Programmer

Cover....1

Title Page....5

Copyright....6

Dedication....7

About the Author....9

About the Technical Reviewer....9

Brief Contents....11

Contents in Detail....13

Acknowledgments....21

Introduction....23

The Power of Coding....24

Why Kotlin?....24

Who Is This Book For?....25

What’s in This Book?....26

The Projects....28

Getting Started....31

Resources....32

Part I: Programming Fundamentals....33

1. Kotlin Basics....35

Using Comments....36

Variables....37

Constants....38

Common Data Types....39

Operators....42

Arithmetic....42

Assignment....44

Unary....44

Relational....44

Logical....45

Working with Strings....46

Concatenation....46

String Templates....47

Escape Sequences....48

Null and Nullable Types....49

Flow Control....50

Conditional Statements....50

Loops....54

Functions....59

Built-in Mathematical Functions....60

Custom Functions....61

Scope Functions....66

Lambda Expressions....67

Basic Input and Output....69

Console-Based Input and Output....69

Simple File Operations....71

Project 1: Build a Console-Based Calculator....72

The Code....73

The Result....76

Summary....77

Resource....77

2. Arrays, Collections, and Classes....79

Arrays....80

Primitive Arrays....81

The Array Constructor....81

Array Operations....82

Multidimensional Arrays....83

Collections....84

Lists....84

Sets....86

Maps....88

An Introduction to Classes....89

Constructors....90

The init Block....93

Methods....94

Encapsulation....95

The this Keyword....96

Inheritance and Polymorphism....97

Common Classes and Custom Types....99

Data Classes....100

Pairs and Triples....102

Abstract Classes....103

Interfaces....104

Enum Classes....106

Copying Objects....107

Shallow Copy....107

Deep Copy....108

Project 2: Build a Versatile Task Manager....110

The Code....110

The Result....116

Summary....117

Resource....118

3. Visualizing with JavaFX....119

Data Visualization Tools for Kotlin....120

An Overview of JavaFX....121

Key Functionalities....121

Setup....122

Project 3: Build “Hello, World!” in JavaFX....122

The Code....124

The Result....127

The JavaFX Object Hierarchy....128

The Stage....128

Scenes....128

Layout Containers....129

Child Nodes....130

Creating JavaFX Charts....130

Project 4: Visualize Data as a Bar Chart....131

The Code....131

The Result....133

Project 5: Create a Multiseries Line Chart....134

The Code....135

The Result....137

Drawing with the Canvas....139

A Simple Shape....139

Common Graphics Context Methods....141

Project 6: Draw a Spiral Seashell....142

The Strategy....142

The Code....143

The Result....147

Animation in JavaFX....147

Project 7: Animate a Square....148

The Code....148

The Result....149

Project 8: Animate a Bouncing Ball....150

Setting Keyframes Explicitly....150

Using an Action Event Listener....152

Summary....156

Resources....156

Part II: Applications in Math and Science....157

4. Solving Mathematical Problems with Code....159

Project 9: Find the Square Root with the Babylonian Algorithm....160

The Code....161

The Result....162

Project 10: Create Pythagorean Triples with Euclid’s Formula....162

The Code....163

The Result....164

Project 11: Identify Prime Numbers with the Sieve of Eratosthenes....165

The Strategy....165

The Code....166

The Result....167

Project 12: Calculate Earth’s Circumference the Ancient Way....168

The Code....170

The Result....171

Project 13: Code the Fibonacci Sequence....171

The Golden Ratio....173

The Fibonacci Spiral....173

The Code....175

The Result....179

Project 14: Find the Shortest Distance Between Two Locations on Earth....180

The Code....182

The Result....185

Project 15: Do Encryption with the Hill Cipher....186

How It Works....186

The Code....189

The Result....195

Project 16: Simulate a One-Dimensional Random Walk....196

A One-Dimensional Model....197

The Code....198

The Result....202

Summary....205

Resources....206

5. Modeling and Simulation....207

Project 17: Predict the Flight of a Cannonball....207

The Strategy....210

The Code....211

The Result....213

Project 18: Design a Fountain with Water Jets....214

The Strategy....216

The Code....216

The Result....220

Project 19: Track a Pendulum’s Motion and Phase....221

The Motion of a Simple Pendulum....222

The Strategy....223

The Code....224

The Result....229

Project 20: The Physics of Coffee Cooling....232

Newton’s Law of Cooling....232

The Effect of Mixing Liquids....233

The Strategy....233

The Code....234

Project 21: Simulate a Binary Star System....241

The Science of Binary Star Systems....242

The Strategy....243

The Code....244

The Result....251

Summary....253

Resources....253

Part III: Recursion, Sorting, and Searching....255

6. Recursive Functions and Fractals....257

The Concept of Fractals....258

Recursive Functions....259

Project 22: The “Hello, World!” of Fractals....261

The Strategy....262

The Code....263

Project 23: Draw the Sierpiński Triangle....266

The Strategy....267

The Code....268

Project 24: Create a Fractal Tree....271

The Strategy....271

The Code....272

The L-System and Turtle Graphics....273

Formalizing the L-System....274

Drawing L-System Patterns with Turtle Graphics....275

Project 25: Design an L-System Simulator....277

The Code....277

The Result....283

The Mighty Mandelbrot Set....284

Project 26: Code and Visualize the Mandelbrot Set....286

The Code....287

The Result....291

Summary....294

Resources....294

7. Sorting and Searchin....297

Sorting Algorithms....298

Project 27: Space-Efficient Sorting with Insertion Sort....300

The Code....301

The Result....302

Project 28: Faster Sorting with Merge Sort....302

The Code....303

The Result....305

Project 29: High-Efficiency Sorting with Quick Sort....306

The Code....307

The Result....309

Search Algorithms....310

What Is a Graph?....310

How to Search a Graph....311

Project 30: Stack-Based Searching with Depth-First Search....312

The Code....313

The Result....314

Project 31: Queue-Based Searching with Breadth-First Search....316

The Code....317

The Result....318

Project 32: Heuristic Searching with A*....320

The Heuristic Function....321

The Algorithm....323

The Code....324

The Result....330

Summary....332

Resources....333

Part IV: Optimization with Nature-Inspired Algorithms....335

8. The Genetic Algorithm....337

Nature-Inspired Algorithms....338

The Optimization Problem....338

When to Use NIAs....341

An Overview of the Genetic Algorithm....342

Genetic Operators....343

Selection....344

Crossover....346

Mutation....347

Elitism....347

Project 33: Evolve Gibberish into Shakespeare....348

The Strategy....348

The Code....348

The Result....353

Project 34: Solve the Knapsack Problem....355

The Strategy....355

The Code....356

The Result....362

Project 35: Optimize a Multivariate Function with the Genetic Algorithm....364

The Strategy....365

The Code....365

The Result....370

Stopping Condition for Genetic Algorithms....373

Summary....375

Resources....375

9. Agent-Based Algorithms....377

An Overview of Particle Swarm Optimization....378

Implementing PSO for Function Minimization....380

Project 36: Optimize a Multivariate Function with a Particle Swarm....382

The Code....382

The Result....386

Ant Colony Optimization....388

The ACS Algorithm....390

Symbols and Their Meanings....390

The Steps of ACS....391

Project 37: Solve the Traveling Salesman Problem with an Ant Colony System....393

The Code....393

The Result....405

Summary....408

Resources....408

Afterword....411

Appendix....413

Key Definitions....413

Workflow for Creating an App....415

Setting Up Shop....416

Step 1: Download and Install IntelliJ IDEA....416

Step 2: Download and Set Up the JDK....417

Step 3: Create a New Project....417

Index....421

Back Cover....435

Kotlin isn’t just for building Android apps. As you’ll learn in Kotlin from Scratch, it’s also a general programming language for crafting both elegant and efficient code.

With the aid of 37 hands-on projects, you’ll move quickly through the language basics while building your problem-solving skills, even tackling advanced concepts like fractals, dynamic systems, and nature-inspired algorithms. You’ll explore the way Kotlin handles variables, control structures, functions, classes, and data structures, and you’ll learn to create visualizations using Kotlin and the JavaFX graphics library. Then you’ll build increasingly sophisticated apps to practice what you’ve learned while tackling challenges from math and science to algorithms and optimization.

As you progress through the book, you will:

• Simulate physical systems, like the intricate dance of binary stars
• Implement the classic Hill cipher for encryption and decryption
• Generate beautiful fractals with recursive algorithms
• Program classic computer science algorithms for sorting and searching
• Solve the infamous Berlin52 traveling salesman problem

Expand your language repertoire and improve your computational thinking with Kotlin from Scratch.