Build Spring Boot Apps with the Kotlin Programming Language

Course details

Kotlin is an exciting programming language that's concise, has immutable variables, and almost always gets rid of null pointer exceptions. If you're a Java developer looking to get started with Kotlin, then this course is for you. Join instructor Matt Greencroft as he demonstrates how to build high-quality Spring Boot applications with Kotlin, specifically the version of Kotlin that runs on the Java Virtual Machine (JVM). As Matt covers a range of key concepts—from classes to loops—he explains how each Kotlin feature compares to the equivalent one in Java.

Learning objectives
Creating a new Kotlin project
Working with strings
Data types in Kotlin
Creating and calling top-level functions
Creating classes
Collections
Throwing exceptions
Class inheritance
Java interoperability
Functional programming
Using JUnit with Kotlin

Concepts

Introduction

Introduction
What is Kotlin
Installing IntelliJ
Configuring IntelliJ

Working with Strings

Creating a new Kotlin project
Variable declaration syntax
Inferring variable types and println
Using string templates
Multiple line strings

Other Variable Types

Using the Double type and determining class types
The Int data type
Other data types
Casting in Java
Casting in Kotlin
Chapter review

Nullable Variables

Creating variables that can contain a null value
Methods that work with nullable parameters
The null-safe and non-null asserted operators
The Nothing object type

Functions

The function syntax and the Unit object
Creating and calling top-level functions
Single expression functions
Using named parameters and optional parameters
Other aspects of functions in Kotlin

Classes

Project structure and packages
The class declaration and class-level attributes
Instantiating a class and accessing class-level attributes
Creating a simple constructor
Secondary constructors
Alternative class design
Overriding getters and setters
Functions within a class
Static functions
Data classes

Practical Exercise 1

Explaining the challenge
Solution walk-through

If and Object Equality

The if keyword as an expression
Using if to do a null-safe check
The let function
Object equality and the when expression

Ranges and Looping

The while loop
Using for to loop through a collection
Destructuring with a for loop
Looping with a range

Collections

Mutable collections with immutable variables
Immutable lists
Mutable lists
Maps and sets
Working with arrays

Practical Exercise 2

Explaining the challenge
Solution walk-through

Exceptions and the try-catch Block

Exceptions are unchecked
Throwing exceptions
try as an expression
use as an expression (try with resources)

Testing

Using JUnit with Kotlin
The Kotlin test assertions
Testing for exceptions

Polymorphism and Inheritance

Creating and implementing interfaces
Class inheritance
Creating custom exceptions
Extension functions

Java Interoperability

Instantiating classes and providing values to non-nullable variables
Using data classes
Using immutable lists
Exception handling
Using static functions
Importing a Kotlin JAR file into a Java project

Getting Started with Spring Boot

Creating a project with the Spring Initializr
A hello world controller
Auto-restarting an application
Overview of the case study
Creating views and backing beans
Connecting views to controller functions
Adding services
Posting to a controller
Dependency injection
Revisiting backing beans

Functional Programming

Functional programming overview
Methods that take function parameters the Java way
Methods that take function parameters the Kotlin way
Functional programming with lists
filter and flatMap
reduce and fold
Working with maps

Getting Started with Hibernate

Adding the Hibernate dependencies
The challenge of creating entities
Persisting data to a database

Practical Exercise 3

Step 1 - Explaining the challenge
Solution walk-through
Mappings between entities
Upgrading the view
Step 2 - Explaining the challenge
Solution walk-through
Step 3 - Explaining the challenge
Solution walk-through

Reflection

The concept of reflection
Inspecting properties and functions
A practical use for reflection
Thank you and goodbye