Complete Kotlin Roadmap: Beginner to Advanced with Projects, Android and Backend Development

This complete Kotlin roadmap covers everything from basic syntax to advanced concepts including object-oriented programming, collections, coroutines, Android development, and backend development with Ktor and Spring Boot. It is designed for beginners and professionals who want to become job-ready Kotlin developers through a structured, chapter-wise learning path with real-world projects and interview preparation.

Chapter 1: Kotlin Fundamentals

1. Introduction to Kotlin

  1. What is Kotlin
  2. Features of Kotlin
  3. Kotlin vs Java
  4. Use cases (Android, Backend, JVM)
  5. Installing IntelliJ IDEA
  6. Kotlin project structure

2. Basic Syntax

  1. main function
  2. Variables: val and var
  3. Data types
  4. Type inference
  5. Comments
  6. String templates
  7. Nullable and non-nullable types

3. Operators

  1. Arithmetic operators
  2. Relational operators
  3. Logical operators
  4. Assignment operators
  5. Unary operators
  6. in and is operators

4. Control Flow

  1. if and else
  2. when expression
  3. for loop
  4. while and do-while
  5. break, continue, return

5. Functions

  1. Function declaration
  2. Parameters and return types
  3. Default arguments
  4. Named arguments
  5. Single expression functions
  6. Local functions

6. Null Safety

  1. Nullable types
  2. Safe call operator
  3. Elvis operator
  4. Non-null assertion
  5. let, run, also, apply

7. Input and Output

  1. Reading user input
  2. Printing output
  3. Output formatting

Mini Projects

  1. Calculator
  2. Number guessing game
  3. Student marks calculator
  4. Temperature converter

Chapter 2: Object-Oriented Programming in Kotlin

8. Classes and Objects

  1. Class declaration
  2. Primary and secondary constructors
  3. Properties
  4. init block
  5. Object creation

9. OOP Concepts

  1. Encapsulation
  2. Inheritance
  3. Polymorphism
  4. Abstraction

10. Visibility and Modifiers

  1. public, private, protected, internal
  2. open, final, override

11. Special Classes

  1. Data classes
  2. Sealed classes
  3. Enum classes
  4. Object and Singleton
  5. Companion object

Mini Projects

  1. Bank account system
  2. Employee management system
  3. Library management system

Chapter 3: Collections and Functional Programming

12. Collections Framework

  1. List (mutable and immutable)
  2. Set
  3. Map
  4. Array vs List
  5. Collection utility functions

13. Functional Programming

  1. Lambda expressions
  2. Higher order functions
  3. Inline functions
  4. Anonymous functions

14. Scope Functions

  1. let
  2. run
  3. apply
  4. also
  5. with

15. Extension Functions and Properties

  1. Creating extension functions
  2. Extension properties

Mini Projects

  1. Address book
  2. Contact management system
  3. To-do list console application

Chapter 4: Advanced Kotlin Concepts

16. Generics

  1. Generic classes
  2. Generic functions
  3. Type constraints
  4. Variance (in and out)

17. Exception Handling

  1. try, catch, finally
  2. Custom exceptions

18. File Handling

  1. Reading files
  2. Writing files
  3. Serialization and deserialization

19. Kotlin Standard Library Concepts

  1. takeIf and takeUnless
  2. lazy and lateinit
  3. apply and also usage

20. Delegation

  1. Class delegation
  2. Property delegation

Mini Projects

  1. File-based student management system
  2. Log file analyzer

Chapter 5: Coroutines and Concurrency

21. Coroutine Basics

  1. What are coroutines
  2. suspend functions
  3. Coroutine scopes
  4. Dispatchers

22. Coroutine Builders

  1. launch
  2. async
  3. withContext
  4. runBlocking

23. Flow and Channels

  1. Cold and hot streams
  2. Flow
  3. StateFlow
  4. SharedFlow
  5. Channels

Mini Projects

  1. API-based weather application
  2. Concurrent file downloader
  3. Chat simulation system

Chapter 6: Kotlin for Android Development

24. Android Fundamentals

  1. Android Studio setup
  2. Activities and Fragments
  3. Lifecycle management
  4. ViewBinding
  5. RecyclerView

25. Android Architecture

  1. MVVM pattern
  2. LiveData
  3. ViewModel
  4. Room database
  5. Retrofit
  6. Coroutines integration

Android Projects

  1. Notes application
  2. Expense tracker
  3. Weather application
  4. News application

Chapter 7: Kotlin for Backend Development

26. Kotlin with Ktor

  1. REST API development
  2. Routing
  3. Authentication
  4. JSON serialization

27. Kotlin with Spring Boot

  1. Spring Boot with Kotlin
  2. REST controllers
  3. JPA and Hibernate
  4. Security using JWT

Backend Projects

  1. User management system
  2. E-commerce backend
  3. Blog application API

Chapter 8: Testing, Tools, and Best Practices

28. Testing

  1. Unit testing concepts
  2. JUnit
  3. MockK
  4. Code coverage

29. Build Tools

  1. Gradle basics
  2. Gradle with Kotlin DSL
  3. Dependency management

30. Best Practices

  1. Clean code principles
  2. SOLID principles
  3. Design patterns
  4. Performance optimization

Chapter 9: Interview Preparation and Career Guidance

31. Kotlin Interview Topics

  1. val vs var
  2. lateinit vs lazy
  3. Coroutines vs threads
  4. Data class usage
  5. Scope function differences
  6. Sealed class vs enum

32. System Design Basics

  1. REST API design
  2. Microservices overview
  3. Authentication and authorization
  4. Caching strategies