Kotlin for Android Developers Learn Kotlin the easy way while developing an Android App

Table of Contents 5 I. About this book 9 II. Is this book for you? 10 III. About the author 11 1 Introduction 12 1.1 What is Kotlin? 12 1.2 What do we get with Kotlin? 13 2 Getting ready 17 2.1 Android Studio 17 2.2 Install Kotlin plugin 18 3 Creating a new project 19 3.1 Create the project in Android Studio 19 3.2 Configure Gradle 19 3.3 Convert MainActivity to Kotlin code 21 3.4 Test that everything works 21 4 Classes and functions 23 4.1 How to declare a class 23 4.2 Class inheritance 23 4.3 Functions 24 4.4 Constructor and functions parameters 24 5 Writing your first class 27 5.1 Creating the layout 27 5.2 The Recycler Adapter 28 6 Variables and properties 30 6.1 Basic types 30 6.2 Variables 31 6.3 Properties 32 7 Anko and Extension Functions 35 7.1 What is Anko? 35 7.2 Start using Anko 35 7.3 Extension functions 36 8 Retrieving data from API 37 8.1 Performing a request 37 8.2 Performing the request out of the main thread 38 9 Data Classes 39 9.1 Extra functions 39 9.2 Copying a data class 39 9.3 Mapping an object into variables 40 10 Parsing data 41 10.1 Converting json to data classes 41 10.2 Shaping the domain layer 42 10.3 Drawing the data in the UI 44 11 Operator overloading 46 11.1 Operators tables 46 11.2 The example 47 11.3 Operators in extension functions 48 12 Making the forecast list clickable 49 13 Lambdas 54 13.1 Simplifying setOnClickListener() 54 13.2 Click listener for ForecastListAdapter 55 13.3 Extending the language 56 14 Visibility Modifiers 58 14.1 Modifiers 58 14.2 Constructors 59 14.3 Revising our code 59 15 Kotlin Android Extensions 60 15.1 How to use Kotlin Android Extensions 60 15.2 Refactoring our code 61 16 Application Singleton and Delegated Properties 64 16.1 Application Singleton 64 16.2 Delegated Properties 65 16.3 Standard Delegates 66 16.4 How to create a custom delegate 69 16.5 Reimplementing App Singleton 70 17 Creating an SQLiteOpenHelper 72 17.1 ManagedSqliteOpenHelper 72 17.2 Tables definition 73 17.3 Implementing SqliteOpenHelper 74 17.4 Dependency injection 76 18 Collections and functional operations 78 18.1 Aggregate operations 79 18.2 Filtering operations 81 18.3 Mapping operations 83 18.4 Elements operations 84 18.5 Generation operations 86 18.6 Ordering operations 87 19 Saving and requesting data from database 89 19.1 Creating database model classes 89 19.2 Writing and requesting data 90 20 Null safety in Kotlin 97 20.1 How Null types work 97 20.2 Nullity and Java libraries 99 21 Creating the business logic to data access 101 22. Flow control and ranges 106 22.1 If Expression 106 22.2 When expression 107 22.3 For loops 108 22.4 While and do/while loops 109 22.5 Ranges 109 23 Creating a Detail Activity 111 23.1 Preparing the request 111 23.2 Providing a new activity 113 23.3 Start an activity: reified functions 118 24 Interfaces and Delegation 120 24.1 Interfaces 120 24.2 Delegation 121 24.3 Implementing an example in our App 122 25 Generics 128 25.1 Basics 128 25.2 Variance 129 25.3 Generics examples 131 26 Settings Screen 134 26.1 Creating the settings activity 134 26.2 Accessing Shared Preferences 135 26.3 Generic preference delegate 138 27 Testing your App 141 27.1 Unit testing 141 27.2 Instrumentation tests 144 28 Extra concepts 148 28.1 Nested classes 148 28.2 Enum classes 148 28.3 Sealed classes 149 28.4 Exceptions 150 29 Conclusion 152