Book Image

Android Programming with Kotlin for Beginners

By : John Horton
5 (1)
Book Image

Android Programming with Kotlin for Beginners

5 (1)
By: John Horton

Overview of this book

Android is the most popular mobile operating system in the world and Kotlin has been declared by Google as a first-class programming language to build Android apps. With the imminent arrival of the most anticipated Android update, Android 10 (Q), this book gets you started building apps compatible with the latest version of Android. It adopts a project-style approach, where we focus on teaching the fundamentals of Android app development and the essentials of Kotlin by building three real-world apps and more than a dozen mini-apps. The book begins by giving you a strong grasp of how Kotlin and Android work together before gradually moving onto exploring the various Android APIs for building stunning apps for Android with ease. You will learn to make your apps more presentable using different layouts. You will dive deep into Kotlin programming concepts such as variables, functions, data structures, Object-Oriented code, and how to connect your Kotlin code to the UI. You will learn to add multilingual text so that your app is accessible to millions of more potential users. You will learn how animation, graphics, and sound effects work and are implemented in your Android app. By the end of the book, you will have sound knowledge about significant Kotlin programming concepts and start building your own fully featured Android apps.

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Table of Contents (33 chapters)
Android Programming with Kotlin for Beginners
Android Programming with Kotlin for Beginners
Contributors
Contributors
Preface
Preface
Free Chapter
1
Getting Started with Android and Kotlin
Getting Started with Android and Kotlin
Why use Kotlin and Android?
The beginner's first stumbling block
How Kotlin and Android work together
Setting up Android Studio
What makes an Android app?
The structure of Android's code
Our first Android app
Deploying the app so far
Frequently asked question
Summary
2
Kotlin, XML, and the UI Designer
Kotlin, XML, and the UI Designer
Examining the log output
Exploring the project's Kotlin code and the main layout's XML code
Adding buttons to the main layout file
Leaving comments in our Kotlin code
Coding messages to the user and the developer
Writing our first Kotlin code
Frequently asked questions
Summary
3
Exploring Android Studio and the Project Structure
Exploring Android Studio and the Project Structure
A quick guided tour of Android Studio
Project Explorer and project anatomy
The Basic Activity project
Exploring the Android emulator
Summary
4
Getting Started with Layouts and Material Design
Getting Started with Layouts and Material Design
Material design
Exploring Android UI design
Layouts
Creating the Exploring Layouts project
Building a menu with LinearLayout
Wiring up the UI with the Kotlin code (part 1)
Adding layouts within layouts
Making the layout look pretty
Wiring up the UI with the Kotlin code (part 2)
Building a precise UI with ConstraintLayout
Laying out data with TableLayout
Summary
5
Beautiful Layouts with CardView and ScrollView
Beautiful Layouts with CardView and ScrollView
Attributes – a quick summary
Building a UI with CardView and ScrollView
Themes and material design
Creating a tablet emulator
Frequently asked question
Summary
6
The Android Lifecycle
The Android Lifecycle
The life and times of an Android app
A simplified explanation of the Android lifecycle
How we handle the lifecycle phases
The lifecycle demo app
Some other overridden functions
The structure of Kotlin code – revisited
Summary
7
Kotlin Variables, Operators, and Expressions
Kotlin Variables, Operators, and Expressions
Learning the jargon
More on code comments
Variables
Operators and expressions
The express yourself demo app
Summary
8
Kotlin Decisions and Loops
Kotlin Decisions and Loops
Making decisions in Kotlin
Repeating code with loops
while loops
do-while loops
Ranges
For loops
Controlling loops with break and continue
Sample code
Summary
9
Kotlin Functions
Kotlin Functions
Function basics and recap
Making functions flexible
Summary
10
Object-Oriented Programming
Object-Oriented Programming
Introducing OOP
Basic classes
Visibility modifiers
Constructors
Basic classes app and using the init block
Introduction to references
Summary
11
Inheritance in Kotlin
Inheritance in Kotlin
OOP and inheritance
Using inheritance with open classes
More polymorphism
Classes using the Inheritance example app
Summary
12
Connecting Our Kotlin to the UI and Nullability
Connecting Our Kotlin to the UI and Nullability
All the Android UI elements are classes too
Kotlin interfaces
Using buttons and TextView widgets from our layout with a little help from interfaces
Nullability – val and var revisited
Summary
13
Bringing Android Widgets to Life
Bringing Android Widgets to Life
Declaring and initializing the objects from the layout
Creating UI widgets from pure Kotlin without XML
Exploring the palette – part 1
Lambdas
Exploring the palette – part 2, and more lambdas
The widget exploration app
Coding the widget exploration app
Running the Widget Exploration app
Converting layouts to ConstraintLayout
Summary
14
Android Dialog Windows
Android Dialog Windows
Dialog windows
The Note to self app
Summary
15
Handling Data and Generating Random Numbers
Handling Data and Generating Random Numbers
A random diversion
Handling large amounts of data with arrays
A simple mini-app array example
Getting dynamic with arrays
ArrayLists
Arrays and ArrayLists are polymorphic
Hashmaps
The Note to self app
Frequently asked questions
Summary
16
Adapters and Recyclers
Adapters and Recyclers
Inner classes
RecyclerView and RecyclerAdapter
Adding RecyclerView, RecyclerAdapter, and ArrayList to the Note to Self project
Running the app
Frequently asked questions
Summary
17
Data Persistence and Sharing
Data Persistence and Sharing
The Android Intent class
Adding a settings page to Note to self
Persisting data with SharedPreferences
Reloading data with SharedPreferences
Making the Note to self settings persist
More advanced persistence
Backing up user data in Note to self
Frequently asked questions
Summary
18
Localization
Localization
Making the Note to self app Spanish, English, and German
Running Note to self in German or Spanish
Summary
19
Animations and Interpolations
Animations and Interpolations
Animations in Android
Animations demo app – introducing SeekBar
Frequently asked questions
Summary
20
Drawing Graphics
Drawing Graphics
Understanding the Canvas class
Using the Canvas class
The Canvas Demo app
The Android coordinate system
Creating bitmap graphics with the Bitmap class
Manipulating bitmaps
The Bitmap manipulation demo app
Frequently asked question
Summary
21
Threads and Starting the Live Drawing App
Threads and Starting the Live Drawing App
Creating the Live Drawing project
Looking ahead at the Live Drawing app
Coding the MainActivity class
Coding the LiveDrawingView class
The game loop
Threads
Implementing the game loop with a thread
Running the app
Summary
22
Particle Systems and Handling Screen Touches
Particle Systems and Handling Screen Touches
Adding custom buttons to the screen
Implementing a particle system effect
Handling touches
Running the app
Summary
23
Android Sound Effects and the Spinner Widget
Android Sound Effects and the Spinner Widget
The SoundPool class
Sound demo app introducing the Spinner widget
Summary
24
Design Patterns, Multiple Layouts, and Fragments
Design Patterns, Multiple Layouts, and Fragments
Introducing the model-view-controller pattern
Android design guidelines
Real-world apps
Device detection mini app
Configuration qualifiers
Fragments
Our first fragment app
Fragment reality check
Frequently asked question
Summary
25
Advanced UI with Paging and Swiping
Advanced UI with Paging and Swiping
The Angry Birds classic swipe menu
Building an image gallery/slider app
Kotlin companion objects
Building a Fragment Pager/slider app
Summary
26
Advanced UI with Navigation Drawer and Fragment
Advanced UI with Navigation Drawer and Fragment
Introducing the NavigationView
Examining the Age Database app
Starting the Age Database project
Exploring the auto-generated code and assets
Coding the Fragment classes and their layouts
Using the Fragment classes and their layouts
Summary
27
Android Databases
Android Databases
Database 101
The SQL syntax primer
The Android SQLite API
Coding the database class
Coding the Fragment classes to use the DataManager class
Running the Age Database app
Summary
28
A Quick Chat Before You Go
A Quick Chat Before You Go
Publishing
Making an app!
Carrying on learning
My other channels
Goodbye and thank you
Other Book You May Enjoy
Other Book You May Enjoy
Leave a review - let other readers know what you think
Index
Index

Exploring the palette – part 2, and more lambdas

Now that we have seen how lambdas and anonymous classes and interfaces work, specifically with RadioGroup and RadioButton, we can now continue exploring the palette and look at working with some more UI widgets.

The Switch widget

The Switch widget is just like a Button widget except that it has two fixed states that can be read and responded to.

An obvious use for the Switch widget is to show and hide something. Remember that in our Kotlin Meet UI app in Chapter 12, Connecting Our Kotlin to the UI and Nullability we used a Button to show and hide a TextView widget?

Each time we hid or showed the TextView widget, we changed the text property on the Button to make it evident what would happen if it was clicked on again. What might have been more intuitive for the user, and more straightforward for us as programmers, would have been to use a Switch widget, as illustrated in the following screenshot:

The following code assumes that we already have...

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