Kotlin Development Complete Guide Create 45 Android Applications Including Jetpack Compose (Henry Codwell) (z-library.sk, 1lib.sk, z-lib.sk)

Complete Guide | Create 45 Android Applications | Including Jetpack Compose KOTLIN Development

Kotlin Development Complete Guide | Create 45 Android Applications | Including Jetpack Compose Henry Codwell

COPYRIGHT NOTICE © 2025. All rights reserved. No portion of Kotlin Development: Complete Guide | Create 45 Android Applications | Including Jetpack Compose may be reproduced, distributed, or transmitted in any form, including but not limited to digital, print, or electronic formats, without prior written permission from the copyright holder. This includes photocopying, recording, scanning, or sharing online. First edition published in 2025.

Table of Contents Introduction O Why Learn Kotlin for Android Development? O Who This Book Is For O How to Use This Book O Overview of the 45 Projects O Setting Up Your Development Environment

Part 1: Getting Started with Kotlin and Android Development 1. Introduction to Kotlin and Android Development O 1.1 Why Kotlin for Android? O 1.2 Evolution of Android and Kotlin’s Role O 1.3 Setting Up Android Studio and SDK O 1.4 Understanding Emulators and Devices O 1.5 Project 1: Hello World Android App O 1.6 Project 2: Simple Calculator App O Summary 1. Kotlin Fundamentals O 2.1 Variables, Data Types, and Operators O 2.2 Control Flow: If, When, and Loops O 2.3 Functions and Lambdas O 2.4 Project 3: Tip Calculator App O 2.5 Project 4: Number Guessing Game O Summary 1. Object-Oriented Programming in Kotlin O 3.1 Classes, Objects, and Inheritance O 3.2 Interfaces and Abstract Classes O 3.3 Null Safety and Smart Casts O 3.4 Project 5: To-Do List App O 3.5 Project 6: Contact Manager App O Summary 1. Android App Basics O 4.1 Android Activities, Fragments, and Intents O 4.2 XML Layouts and UI Components O 4.3 Handling User Input and Events O 4.4 Project 7: Weather Display App (Static Data) O 4.5 Project 8: Quiz App O Summary

Part 2: Intermediate Kotlin and Android Concepts 1. Kotlin Collections and Functional Programming O 5.1 Lists, Sets, Maps, and Filtering O 5.2 Higher-Order Functions O 5.3 Scope Functions: let, apply, run O 5.4 Project 9: Shopping List App O 5.5 Project 10: Movie Catalog App O Summary 1. Working with Android Views and Layouts O 6.1 Advanced XML Layouts: ConstraintLayout O 6.2 RecyclerView and Adapters O 6.3 ViewHolders and Performance O 6.4 Project 11: Social Media Feed App O 6.5 Project 12: Image Gallery App O Summary 1. Data Persistence in Android O 7.1 SharedPreferences for Lightweight Storage O 7.2 Room Database for Structured Data O 7.3 File Storage and External Storage O 7.4 Project 13: Note-Taking App O 7.5 Project 14: Expense Tracker App O Summary 1. Networking and APIs in Android O 8.1 Using Retrofit for REST API Calls O 8.2 Parsing JSON with Gson O 8.3 Error Handling and Caching O 8.4 Project 15: Weather App (Live API Data) O 8.5 Project 16: News Reader App O Summary

Part 3: Mastering Jetpack Compose 1. Introduction to Jetpack Compose O 9.1 Why Jetpack Compose? O 9.2 Composables, State, and Recomposition O 9.3 Building Basic UI with Compose O 9.4 Project 17: Counter App with Compose O 9.5 Project 18: Profile Card App O Summary 1. Advanced Jetpack Compose O 10.1 Layouts, Modifiers, and Theming O 10.2 Handling User Interactions O 10.3 Navigation and Animations O 10.4 Project 19: E-Commerce Product List App O 10.5 Project 20: Music Player UI O Summary 1. Integrating Compose with Legacy Code O 11.1 Using Compose in XML-Based Apps O 11.2 Interoperability with ViewModels O 11.3 Migration Strategies O 11.4 Project 21: Hybrid To-Do App (Compose + XML) O 11.5 Project 22: Fitness Tracker UI O Summary 1. Jetpack Compose Best Practices O 12.1 Performance Optimization O 12.2 Testing Compose UIs O 12.3 Accessibility in Compose O 12.4 Project 23: Recipe App O 12.5 Project 24: Event Planner App O Summary

Part 4: Advanced Android Development with Kotlin 1. Kotlin Coroutines for Asynchronous Programming O 13.1 Understanding Coroutines and Flows O 13.2 Managing Background Tasks O 13.3 Error Handling and Cancellation O 13.4 Project 25: Live Stock Ticker App O 13.5 Project 26: Chat App (Simulated Backend) O Summary 1. Android Architecture Components O 14.1 ViewModel, LiveData, and StateFlow O 14.2 Navigation Component for Single-Activity Apps O 14.3 WorkManager for Background Tasks O 14.4 Project 27: Task Scheduler App O 14.5 Project 28: Location Tracker App O Summary 1. Dependency Injection with Hilt O 15.1 Introduction to Hilt and Dagger O 15.2 Setting Up Dependency Injection O 15.3 Testing with Dependency Injection O 15.4 Project 29: Movie Review App O 15.5 Project 30: Blog Reader App O Summary 1. Publishing and Monetizing Android Apps O 16.1 Preparing Apps for Google Play O 16.2 App Signing and Optimization O 16.3 In-App Purchases and Ads O 16.4 Project 31: Subscription-Based Wallpaper App O 16.5 Project 32: Ad-Supported Game App O Summary

Part 5: Capstone Projects and Beyond 1. Building a Full-Stack Android App O 17.1 Integrating Firebase for Authentication O 17.2 Real-Time Database and Cloud Functions O 17.3 Security and Scalability O 17.4 Project 33: Social Networking App O 17.5 Project 34: E-Learning Platform O Summary 1. Advanced UI/UX with Jetpack Compose O 18.1 Custom Composables O 18.2 Advanced Animations O 18.3 Material 3 Design Principles O 18.4 Project 35: Travel Booking App O 18.5 Project 36: Food Delivery App O Summary 1. Cross-Platform Development with Kotlin O 19.1 Introduction to Kotlin Multiplatform Mobile (KMM) O 19.2 Sharing Code Between Android and iOS O 19.3 Challenges and Best Practices O 19.4 Project 37: Shared To-Do App (Android + iOS) O 19.5 Project 38: Cross-Platform Weather App O Summary 1. Next Steps in Your Android Journey O 21.1 Contributing to Open-Source Android Projects O 21.2 Preparing for Android Developer Certifications O 21.3 Building a Portfolio and Landing a Job O 21.4 Resources for Continuous Learning O Summary Appendices • Appendix A: Kotlin Cheat Sheet • Appendix B: Android Studio Tips and Tricks • Appendix C: Common Android Development Errors and Solutions • Appendix D: Glossary of Terms • Appendix E: Additional Resources

Index

PREFACE Why Learn Kotlin for Android Development? When I first dipped my toes into Android development, the landscape was dominated by Java—a language that, while powerful, often felt like wading through molasses. The boilerplate code, verbose syntax, and occasional null pointer exceptions were enough to make any developer question their life choices. Then, in 2017, Google announced Kotlin as a first-class language for Android development, and everything changed. It was like someone handed me a sleek, modern toolkit after years of using a rusty wrench. Kotlin didn’t just make Android development easier; it made it enjoyable. Today, as I write this book, Kotlin is not just a trend—it’s the gold standard for building Android apps, and understanding why it’s worth learning is the first step to unlocking its potential. Kotlin, developed by JetBrains, is a statically typed, modern programming language that runs on the Java Virtual Machine (JVM). Its design philosophy prioritizes conciseness, safety, and interoperability, making it a perfect fit for Android’s complex ecosystem. Unlike Java, which can feel cumbersome with its lengthy syntax, Kotlin allows you to express the same logic in fewer lines, often with cleaner, more readable code. For example, a simple data class in Java might require dozens of lines to define fields, getters, setters, and methods like toString() or equals(). In Kotlin, you can achieve the same functionality with a single line: data class Person(val name: String, val age: Int). This brevity isn’t just about saving keystrokes— it’s about reducing cognitive load, letting you focus on building features rather than wrestling with syntax. One of Kotlin’s standout features is its null safety system. If you’ve ever been haunted by a

NullPointerException crashing your app at 2 a.m., you’ll appreciate Kotlin’s approach. By distinguishing between nullable and non-nullable types at the language level, Kotlin forces you to handle null cases explicitly. This means you’re less likely to encounter those dreaded runtime crashes that plague Java-based Android apps. For instance, declaring a variable as var name: String? signals that it can be null, and the compiler ensures you check for null before using it. This feature alone has saved countless hours of debugging and made apps more robust, especially in the fast-paced world of Android development where user expectations are sky-high. Beyond null safety, Kotlin’s support for functional programming paradigms brings a fresh perspective to Android development. Features like higher-order functions, lambdas, and extension functions let you write more expressive and reusable code. For example, you can extend existing classes with new functionality without inheritance, making your codebase more modular. Imagine adding a custom method to the String class to format a phone number: fun String.formatPhoneNumber(): String. This kind of flexibility is a game-changer when building complex Android apps with intricate user interfaces and data flows. Kotlin’s integration with Android is seamless, thanks to Google’s wholehearted endorsement. Since 2019, Google has declared Kotlin as the preferred language for Android development, and the Android SDK, libraries, and tools have been optimized for it. Jetpack libraries, Android’s architecture components, and even

the modern UI toolkit Jetpack Compose are all designed with Kotlin in mind. This means you’re not just learning a language—you’re aligning with the future of Android development. Most new Android documentation and sample code from Google are now Kotlin-first, and major companies like Netflix, Uber, and Pinterest have adopted Kotlin for their Android apps, proving its reliability in production. Another reason to learn Kotlin is its interoperability with Java. If you’re transitioning from a Java-based Android project or working on a legacy codebase, Kotlin plays nicely with existing Java code. You can call Java methods from Kotlin and vice versa without jumping through hoops. This makes Kotlin a practical choice for both new projects and gradual migrations, allowing teams to modernize their apps without rewriting everything from scratch. For solo developers or small teams, this flexibility is invaluable, as it lowers the barrier to adopting Kotlin while reaping its benefits. The learning curve for Kotlin is surprisingly gentle, especially if you have experience with Java or another object-oriented language. Its syntax is intuitive, and features like smart casts, type inference, and concise lambdas feel like natural extensions of what a modern language should offer. Even if you’re new to programming, Kotlin’s clear error messages and robust tooling in Android Studio make it easier to learn than Java’s often cryptic compiler feedback. JetBrains’ involvement ensures that Kotlin is backed by world-class IDE support, with features like autocompletion, refactoring, and debugging that make development a breeze. Kotlin also opens doors beyond Android. While this book focuses on Android development, Kotlin’s versatility allows you to explore other domains, such as server-side development with frameworks like Spring Boot or cross-platform mobile development with Kotlin Multiplatform Mobile (KMM). Learning Kotlin is an investment in a skillset that can grow with you, whether you’re building apps for Google Play, contributing to open-source projects, or exploring new technologies. The Android ecosystem is vast, with billions of devices worldwide, and Kotlin is at its heart. As Android continues to power smartphones, tablets, wearables, TVs, and even cars, the demand for skilled Kotlin developers is only growing. By

mastering Kotlin, you’re not just learning to code—you’re positioning yourself to create apps that reach millions, solve real-world problems, and maybe even land you a dream job at a tech giant. This book is your guide to that journey, and it all starts with understanding why Kotlin is worth your time. It’s not just about writing code; it’s about building the future, one app at a time.

Who This Book Is For Writing a book like this is a bit like designing an app—you have to know your users. When I sat down to plan Kotlin Development: Complete Guide | Create 45 Android Applications | Including Jetpack Compose, I pictured a diverse group of people, each with their own goals, backgrounds, and dreams. This book isn’t just for one type of reader; it’s for anyone who’s curious about Android development and ready to dive into Kotlin, whether you’re taking your first steps or looking to level up. Let me paint a picture of who you might be and why this book is written for you. First, there’s the beginner. Maybe you’ve dabbled in programming—perhaps you’ve written some Python scripts, tinkered with JavaScript, or even taken a college course on C++. You understand loops, variables, and maybe what a function does, but Android development feels like a big, intimidating leap. You’ve heard about Kotlin, seen job postings mentioning it, or maybe you just want to build that app idea that’s been buzzing in your head. If this is you, this book is your starting point. I’ve designed it to assume only basic programming knowledge, walking you through Kotlin’s syntax, Android’s ecosystem, and the tools you’ll need, like Android Studio. The early chapters are gentle, with simple projects like a calculator or a to-do list app to build your confidence. By the time you’re building complex apps with Jetpack Compose, you’ll be amazed at how far you’ve come. Then there’s the intermediate developer. You might already be working in Android, perhaps with Java, and you’ve built a few apps—maybe a weather app or a note-taking tool. But Kotlin is calling, and you know it’s the future. You’ve seen how Jetpack Compose is changing the game, and you want to modernize your skills to stay competitive. Or maybe you’re self-taught, piecing together tutorials from YouTube and Stack Overflow, but you’re craving a structured, comprehensive guide to fill in the gaps. This book is for you, too. The middle sections dive into Kotlin’s advanced features, like coroutines and functional programming, and show you how to build robust apps with modern Android architecture. Projects like a social media feed or a news reader app will push you to think like a pro, and the focus on Jetpack Compose ensures you’re learning what employers and users expect in 2025.

There’s also the professional developer, someone who’s been in the trenches, maybe working on enterprise apps or freelancing. You know your way around Android, but you want to master Kotlin’s nuances—things like dependency injection with Hilt, cross-platform development with Kotlin Multiplatform, or building sleek UIs with Jetpack Compose. You’re not here for hand-holding; you want deep, practical knowledge to take your projects to the next level or to prepare for that senior developer role. This book has you covered with advanced topics and capstone projects, like a fitness coaching app or an augmented reality experience, that are portfolio-worthy and showcase your expertise. I also wrote this book with career changers in mind. Maybe you’re in a different field—teaching, marketing, or even healthcare—but you’ve always been curious about tech. You’ve decided to take the plunge, learn to code, and build apps that could change lives or maybe just make your own life more fun. Android’s massive market share makes it an exciting place to start, and Kotlin’s beginner-friendly design means you don’t need a computer science degree to succeed. The step-by- step projects and clear explanations in this book are designed to make your transition smooth, with plenty of real-world examples to keep you motivated. Students, hobbyists, and entrepreneurs also have a place here. If you’re a student looking to stand out in a competitive job market, the 45 projects in this book will give you a portfolio that screams “hire me.” If you’re a hobbyist who loves tinkering with code, you’ll find joy in building everything from a music player to a charity donation app. And if you’re an entrepreneur with a startup idea, this book will equip you to prototype your app, test it, and even publish it on Google Play, all while keeping costs low by doing it yourself. No matter who you are, this book assumes you’re curious, determined, and ready to learn. It’s not about memorizing syntax or passing a test—it’s about building real, functional apps that solve problems and spark creativity. Whether you’re aiming for a career in tech, a side hustle, or just the satisfaction of seeing your app on someone’s phone, you’re in the right place. I’ve poured my years of experience as a developer and teacher into these pages to make sure you have everything you need to succeed. So, whoever you are, welcome to the journey of becoming an Android developer with Kotlin.

How to Use This Book When I started learning Android development, I remember flipping through thick programming books, feeling overwhelmed by walls of text and cryptic code snippets. Some books were too theoretical, others too shallow, and few explained how to actually use them to learn effectively. With Kotlin Development: Complete Guide | Create 45 Android Applications | Including Jetpack Compose, I wanted to create something different—a book that feels like a mentor guiding you through a hands-on workshop, not a lecture hall. This section is your roadmap for getting the most out of these pages, whether you’re a beginner tackling your first app or a seasoned developer diving into Jetpack Compose. The book is structured to take you from zero to hero, with a clear progression from foundational concepts to advanced techniques. It’s divided into five parts, each building on the previous one, and includes 45 projects that range from simple utilities to complex, portfolio-ready apps. But it’s not enough to just read the chapters or copy the code—you need a strategy to make the material stick and turn knowledge into skills. Here’s how to approach this book to maximize your learning and have fun along the way. Start by reading the preface and introduction to understand the big picture: why Kotlin matters, who this book is for (spoiler: you!), and what the 45 projects entail. These sections set the context and help you align your goals with the book’s structure. If you’re new to Android or Kotlin, don’t skip the setup guide in “Setting Up Your Development Environment.” It’s tempting to jump straight to coding, but taking the time to configure Android Studio properly will save you headaches later. Each chapter follows a consistent pattern: theory, code examples, hands-on projects, and a summary. The theory sections explain concepts in plain language, using analogies and real-world scenarios to make abstract ideas concrete. For example, when we talk about Kotlin’s null safety, I compare it to checking if a package has arrived before opening it. Read these sections actively—take notes, highlight key points, or even explain the concept to a friend (or your dog, no judgment). If a term feels unfamiliar, check the glossary in Appendix D or the Kotlin cheat sheet in Appendix A for quick reference.

The code examples are your chance to see theory in action. I’ve included complete, commented code snippets that you can type out or download from the book’s GitHub repository (linked in the introduction). Typing the code yourself, rather than copying and pasting, helps reinforce what you’ve learned. As you work through the examples, experiment a little—change a variable, tweak a function, or add a new feature. Breaking things and fixing them is one of the best ways to understand how code works. If you get stuck, Appendix C has solutions to common Android development errors, and the GitHub repo includes working versions of all examples. The heart of this book is the 45 projects, spread across the chapters. These aren’t just exercises—they’re real apps you can run, modify, and show off. Each project is designed to teach specific skills while building something useful, like a weather app, a music player, or a social networking platform. Follow the step-by- step instructions to build each app, but don’t stop there. After completing a project, challenge yourself to customize it. For example, if you build the to-do list app in Chapter 3, try adding a feature to categorize tasks or change the UI colors. This hands-on experimentation is where the real learning happens. If you’re a beginner, work through the book sequentially. Part 1 covers the basics of Kotlin and Android, and each chapter builds on the previous one. Don’t rush— spend time mastering the fundamentals, like Kotlin’s syntax or Android’s activity lifecycle, before moving to Part 2. If you’re an intermediate or advanced developer, you can jump to specific sections, like Part 3 on Jetpack Compose or Part 4 on coroutines and architecture components. However, even experienced developers might benefit from skimming earlier chapters for Kotlin-specific nuances or modern Android best practices. Time management is key. Learning Android development is a marathon, not a sprint. Aim to complete one chapter or project per week, depending on your schedule. If you’re dedicating a few hours a day, you might finish a chapter in a couple of days, but don’t sacrifice understanding for speed. Set up a dedicated workspace with minimal distractions, and keep Android Studio open so you can test code as you read. Treat the projects like mini-milestones—celebrate when you get an app running on your emulator or phone.

The book includes visual aids, like screenshots of Android Studio and app UIs, to guide you. Pay attention to these, as they show exactly what your screen should look like at key steps. Sidebars labeled “Pro Tip,” “Common Pitfall,” and “Did You Know?” offer extra insights, like shortcuts in Android Studio or mistakes to avoid. These are drawn from my own years of trial and error, so think of them as advice from a friend who’s been there. If you hit a roadblock—and you will, because coding is hard—don’t panic. Check the troubleshooting tips in Appendix C, search the GitHub repo for solutions, or visit online communities like Stack Overflow or Reddit’s r/androiddev. The book’s companion website (if available) may also have video tutorials or errata to clarify tricky topics. Persistence is more important than instant mastery, and every bug you fix makes you a better developer. Finally, use this book as a springboard, not a finish line. The capstone projects in Part 5 are designed to be portfolio pieces, so polish them, publish them on Google Play, or share them on your GitHub profile. The final chapter, “Next Steps in Your Android Journey,” offers advice on open-source contributions, certifications, and job hunting. Keep learning by exploring the resources in Appendix E, like blogs, podcasts, and Kotlin user groups. This book is your partner in the exciting, sometimes frustrating, always rewarding world of Android development. Approach it with curiosity, patience, and a willingness to experiment, and you’ll not only learn Kotlin but also build apps you’re proud of. Let’s get coding. Overview of the 45 Projects One of the things I love about teaching Android development is watching someone’s face light up when they run their first app on a real device. There’s something magical about turning lines of code into something tangible—a button that responds, a list that scrolls, or a notification that pops up exactly when it’s supposed to. That’s why I made the 45 projects the backbone of Kotlin Development: Complete Guide | Create 45 Android Applications | Including Jetpack Compose. These aren’t throwaway exercises; they’re real, functional apps that teach you Kotlin and Android development while giving you a portfolio

to show the world. In this section, I’ll walk you through what these projects are, why they matter, and how they’re designed to make you a confident developer. The 45 projects are spread across the book’s 21 chapters, with two to three projects per chapter, except for Chapter 20, which packs seven capstone projects. They’re carefully sequenced to match the book’s learning curve, starting with simple apps in Part 1 and progressing to complex, full-stack applications in Part 5. Each project is a complete Android app you can run on an emulator or device, and they cover a wide range of app types—utilities, games, social apps, e-commerce, and more. This variety ensures you’re not just learning to code but also exploring the diverse possibilities of Android. In Part 1, the projects are beginner-friendly, focusing on Kotlin basics and core Android concepts. For example, Project 1 is a “Hello World” app that gets you comfortable with Android Studio and the app-building process. Project 2, a simple calculator, introduces user input and basic UI components. By the time you reach Project 8, a quiz app, you’re working with activities, intents, and XML layouts. These early projects are short, taking a few hours each, and they build your confidence while teaching foundational skills. Part 2 ramps up the complexity with intermediate projects that dive into Kotlin’s advanced features and Android’s core components. Project 9, a shopping list app, teaches you about collections and functional programming, while Project 12, an image gallery app, shows you how to use RecyclerView for dynamic lists. Projects like the weather app (Project 15) and news reader (Project 16) introduce networking with Retrofit and JSON parsing, skills that are essential for real- world apps. These projects are more involved, often requiring a day or two, and they push you to think about data management and user experience. Part 3 is where things get exciting, as it focuses on Jetpack Compose, Google’s modern UI toolkit. The projects here, like a counter app (Project 17) and an e­ commerce product list (Project 19), teach you to build sleek, responsive interfaces with less code than traditional XML layouts. By Project 24, an event planner app, you’re optimizing Compose UIs for performance and accessibility. These projects are designed to make you proficient in Compose, a skill that’s in high demand as Android shifts away from older UI frameworks.