Kotlin Essentials

Introduction

1. Who is this book for?
2. What will be covered?
3. The Kotlin for Developers series
4. My story
5. Conventions
6. Code conventions
7. Exercises and solutions
8. Acknowledgments

What is Kotlin?

1. Kotlin platforms
2. The Kotlin IDE
3. Where do we use Kotlin?

Your first program in Kotlin

1. Live templates
2. What is under the hood on JVM?
3. Packages and importing
4. Summary
5. Exercise: Your first program

Variables

Basic types, their literals and operations

1. Numbers
2. Booleans
3. Characters
4. Strings
5. Summary
6. Exercise: Basic values operations

Conditional statements

1. if-statement
2. when-statement
3. when-statement with a value
4. is check
5. Explicit casting
6. Smart-casting
7. While and do-while statements
8. Summary
9. Exercise: Using when
10. Exercise: Pretty time display

Functions

1. Single-expression functions
2. Functions on all levels
3. Parameters and arguments
4. Unit return type
5. Vararg parameters
6. Named parameter syntax and default arguments
7. Function overloading
8. Infix syntax
9. Function formatting
10. Summary
11. Exercise: Person details display

The power of the for-loop

1. Ranges
2. Break and continue
3. Use cases
4. Summary
5. Exercise: Range Operations

Nullability

1. Safe calls
2. Not-null assertion
3. Smart-casting
4. The Elvis operator
5. Extensions on nullable types
6. null is our friend
7. lateinit
8. Summary
9. Exercise: User Information Processor

Classes

1. Member functions
2. Properties
3. Constructors
4. Classes representing data in Kotlin and Java
5. Inner classes
6. Summary
7. Exercise: Implementing the Product class

Inheritance

1. Overriding elements
2. Parents with non-empty constructors
3. Super call
4. Abstract class
5. Interfaces
6. Visibility
7. Any
8. Summary
9. Exercise: GUI View Hierarchy Simulation

Data classes

1. Transforming to a string
2. Objects equality
3. Hash code
4. Copying objects
5. Destructuring
6. When and how should we use destructuring?
7. Data class limitations
8. Prefer data classes instead of tuples
9. Summary
10. Exercise: Data class practice

Objects

1. Object expressions
2. Object declaration
3. Companion objects
4. Data object declarations
5. Constant values
6. Summary
7. Exercise: Pizza factory

Exceptions

1. Throwing exceptions
2. Defining exceptions
3. Catching exceptions
4. A try-catch block used as an expression
5. The finally block
6. Important exceptions
7. The hierarchy of exceptions
8. Summary
9. Exercise: Catching exceptions

Enum classes

1. Data in enum values
2. Enum classes with custom methods
3. Summary
4. Exercise: Days of the week enum

Sealed classes and interfaces

1. Sealed classes and when expressions
2. Sealed vs enum
3. Use cases
4. Summary

Annotation classes

1. Meta-annotations
2. Annotating the primary constructor
3. List literals
4. Summary

Extensions

1. Extension functions under the hood
2. Extension properties
3. Extensions vs members
4. Extension functions on object declarations
5. Member extension functions
6. Use cases
7. Summary
8. Exercise: Conversion and measurement unit creation

Collections

1. The hierarchy of interfaces
2. Mutable vs read-only types
3. Creating collections
4. Lists
5. Sets
6. Maps
7. Using arrays in practice
8. Summary
9. Exercise: Inventory management

Operator overloading

1. An example of operator overloading
2. Arithmetic operators
3. The in operator
4. The iterator operator
5. The equality and inequality operators
6. Comparison operators
7. The indexed access operator
8. Augmented assignments
9. Unary prefix operators
10. Increment and decrement
11. The invoke operator
12. Precedence
13. Summary
14. Exercise: Money operations

The beauty of Kotlin’s type system

1. What is a type?
2. Why do we have types?
3. The relation between classes and types
4. Class vs type in practice
5. The relationship between types
6. The subtype of all the types: Nothing
7. The result type from return and throw
8. When is some code not reachable?
9. The type of null
10. Summary
11. Exercise: The closest supertype of types

Generics

1. Generic functions
2. Generic classes
3. Generic classes and nullability
4. Generic interfaces
5. Type parameters and inheritance
6. Type erasure
7. Generic constraints
8. Star projection
9. Underscore operator for type arguments
10. Summary
11. Exercise: Stock

Final words

1. Final Project: Workout manager

Exercise solutions