Project with exercises

Introduction

Kotlin platforms

The Kotlin IDE

Where do we use Kotlin?

Live templates

What is under the hood on JVM?

Packages and importing

Summary

Exercise: Your first program

Numbers

Underscores in numbers

Other numeral systems

Number and conversion functions

Operations on numbers

Operations on bits

BigDecimal and BigInteger

Booleans

Equality

Boolean operations

Characters

Strings

Summary

Exercise: Basic values operations

if-statement

when-statement

when-statement with a value

is check

Explicit casting

Smart-casting

While and do-while statements

Summary

Exercise: Using when

Exercise: Pretty time display

Single-expression functions

Functions on all levels

Parameters and arguments

Unit return type

Vararg parameters

Named parameter syntax and default arguments

Function overloading

Infix syntax

Function formatting

Summary

Exercise: Person details display

Ranges

Break and continue

Use cases

Summary

Exercise: Range Operations

Safe calls

Not-null assertion

Smart-casting

The Elvis operator

Extensions on nullable types

null is our friend

lateinit

Summary

Exercise: User Information Processor

Member functions

Properties

Constructors

Classes representing data in Kotlin and Java

Inner classes

Summary

Exercise: Implementing the Product class

Overriding elements

Parents with non-empty constructors

Super call

Abstract class

Interfaces

Visibility

Any

Summary

Exercise: GUI View Hierarchy Simulation

Transforming to a string

Objects equality

Hash code

Copying objects

Destructuring

When and how should we use destructuring?

Data class limitations

Prefer data classes instead of tuples

Summary

Exercise: Data class practice

Object expressions

Object declaration

Companion objects

Data object declarations

Constant values

Summary

Exercise: Pizza factory

Throwing exceptions

Defining exceptions

Catching exceptions

A try-catch block used as an expression

The finally block

Important exceptions

The hierarchy of exceptions

Summary

Exercise: Catching exceptions

Data in enum values

Enum classes with custom methods

Summary

Exercise: Days of the week enum

Sealed classes and when expressions

Sealed vs enum

Use cases

Summary

Meta-annotations

Annotating the primary constructor

List literals

Summary

Extension functions under the hood

Extension properties

Extensions vs members

Extension functions on object declarations

Member extension functions

Use cases

Summary

Exercise: Conversion and measurement unit creation

The hierarchy of interfaces

Mutable vs read-only types

Creating collections

Lists

Modifying lists

Checking a list’s size or if it is empty

Lists and indices

Checking if a list contains an element

Iterating over a list

Sets

Modifying sets

Elements in a set are unique

Checking a set’s size or if it is empty

Checking if a set contains an element

Iterating over sets

Maps

Finding a value by a key

Adding elements to a map

Checking if a map contains a key

Checking map size

Iterating over maps

Mutable maps

Using arrays in practice

Arrays of primitives

Vararg parameters and array functions

Summary

Exercise: Inventory management

An example of operator overloading

Arithmetic operators

The in operator

The iterator operator

The equality and inequality operators

Comparison operators

The indexed access operator

Augmented assignments

Unary prefix operators

Increment and decrement

The invoke operator

Precedence

Summary

Exercise: Money operations

What is a type?

Why do we have types?

The relation between classes and types

Class vs type in practice

The relationship between types

The subtype of all the types: Nothing

The result type from return and throw

When is some code not reachable?

The type of null

Summary

Exercise: The closest supertype of types

Generic functions

Generic classes

Generic classes and nullability

Generic interfaces

Type parameters and inheritance

Type erasure

Generic constraints

Star projection

Underscore operator for type arguments

Summary

Exercise: Stock

Exercise solutions