Table of Contents

Learning Android

Prerequisites

What’s New in the Third Edition?

How to Use This Book

How This Book Is Organized

Challenges

Are you more curious?

Code Style

Typographical Conventions

Using an eBook

Android Versions

The Necessary Tools

Downloading and Installing Android Studio

Downloading Earlier SDK Versions

A Hardware Device

1. Your First Android Application

App Basics

Creating an Android Project

Navigating in Android Studio

Laying Out the UI

The view hierarchy

Widget attributes

Creating string resources

Previewing the layout

From Layout XML to View Objects

Resources and resource IDs

Wiring Up Widgets

Getting references to widgets

Setting listeners

Making Toasts

Using code completion

Running on the Emulator

For the More Curious: Android Build Process

Android build tools

Challenges

Challenge: Customizing the Toast

2. Android and Model-View-Controller

Creating a New Class

Generating getters and setters

Model-View-Controller and Android

Benefits of MVC

Updating the View Layer

Updating the Controller Layer

Running on a Device

Connecting your device

Configuring your device for development

Adding an Icon

Adding resources to a project

Referencing resources in XML

Challenge: Add a Listener to the TextView

Challenge: Add a Previous Button

Challenge: From Button to ImageButton

3. The Activity Lifecycle

Logging the Activity Lifecycle

Making log messages

Using Logcat

Exploring the activity lifecycle by example

Rotation and the Activity Lifecycle

Device configurations and alternative resources

Saving Data Across Rotation

Overriding onSaveInstanceState(Bundle)

The Activity Lifecycle, Revisited

For the More Curious: Current State of Activity Cleanup

For the More Curious: Log Levels and Methods

Challenge: Preventing Repeat Answers

Challenge: Graded Quiz

4. Debugging Android Apps

Exceptions and Stack Traces

Diagnosing misbehaviors

Logging stack traces

Setting breakpoints

Using exception breakpoints

Android-Specific Debugging

Using Android Lint

Issues with the R class

Challenge: Exploring the Layout Inspector

Challenge: Exploring Allocation Tracking

5. Your Second Activity

Setting Up a Second Activity

Creating a new activity

A new activity subclass

Declaring activities in the manifest

Adding a cheat button to QuizActivity

Starting an Activity

Communicating with intents

Passing Data Between Activities

Using intent extras

Getting a result back from a child activity

How Android Sees Your Activities

Challenge: Closing Loopholes for Cheaters

6. Android SDK Versions and Compatibility

Android SDK Versions

Compatibility and Android Programming

A sane minimum

Minimum SDK version

Target SDK version

Compile SDK version

Adding code from later APIs safely

Using the Android Developer Documentation

Challenge: Reporting the Build Version

Challenge: Limited Cheats

7. UI Fragments and the Fragment Manager

The Need for UI Flexibility

Introducing Fragments

Starting CriminalIntent

Creating a new project

Two types of fragments

Adding dependencies in Android Studio

Creating the Crime class

Hosting a UI Fragment

The fragment lifecycle

Two approaches to hosting

Defining a container view

Creating a UI Fragment

Defining CrimeFragment’s layout

Creating the CrimeFragment class

Adding a UI Fragment to the FragmentManager

Fragment transactions

The FragmentManager and the fragment lifecycle

Application Architecture with Fragments

The reason all our activities will use fragments

For the More Curious: Fragments and the Support Library

For the More Curious: Why Support Fragments Are Superior

8. Displaying Lists with RecyclerView

Updating CriminalIntent’s Model Layer

Singletons and centralized data storage

An Abstract Activity for Hosting a Fragment

A generic fragment-hosting layout

An abstract Activity class

RecyclerView, Adapter, and ViewHolder

ViewHolders and Adapters

Using a RecyclerView

A view to display

Implementing a ViewHolder and an Adapter

Binding List Items

Responding to Presses

For the More Curious: ListView and GridView

For the More Curious: Singletons

Challenge: RecyclerView ViewTypes

9. Creating User Interfaces with Layouts and Widgets

Using the Graphical Layout Tool

Introducing ConstraintLayout

Using ConstraintLayout

The graphical editor

Making room

Adding widgets

ConstraintLayout’s inner workings

Editing properties

Making list items dynamic

More on Layout Attributes

Screen pixel densities and dp and sp

Margins vs padding

Styles, themes, and theme attributes

Android’s design guidelines

The Graphical Layout Tools and You

Challenge: Formatting the Date

10. Using Fragment Arguments

Starting an Activity from a Fragment

Putting an extra

Retrieving an extra

Updating CrimeFragment’s view with Crime data

The downside to direct retrieval

Fragment Arguments

Attaching arguments to a fragment

Retrieving arguments

Reloading the List

Getting Results with Fragments

For the More Curious: Why Use Fragment Arguments?

Challenge: Efficient RecyclerView Reloading

Challenge: Improving CrimeLab Performance

11. Using ViewPager

Creating CrimePagerActivity

ViewPager and PagerAdapter

Integrating CrimePagerActivity

FragmentStatePagerAdapter vs FragmentPagerAdapter

For the More Curious: How ViewPager Really Works

For the More Curious: Laying Out Views in Code

Challenge: Restoring CrimeFragment’s Margins

Challenge: Adding First and Last Buttons

12. Dialogs

Creating a DialogFragment

Showing a DialogFragment

Setting a dialog’s contents

Passing Data Between Two Fragments

Passing data to DatePickerFragment

Returning data to CrimeFragment

Challenge: More Dialogs

Challenge: A Responsive DialogFragment

13. The Toolbar

AppCompat

Using the AppCompat library

Menus

Defining a menu in XML

Creating the menu

Responding to menu selections

Enabling Hierarchical Navigation

How hierarchical navigation works

An Alternative Action Item

Toggling the action item title

“Just one more thing...”

For the More Curious: Action Bar vs Toolbar

Challenge: Deleting Crimes

Challenge: Plural String Resources

Challenge: An Empty View for the RecyclerView

14. SQLite Databases

Defining a Schema

Building Your Initial Database

Exploring files using Android Device Monitor

Debugging database issues

Gutting CrimeLab

Writing to the Database

Using ContentValues

Inserting and updating rows

Reading from the Database

Using a CursorWrapper

Converting to model objects

For the More Curious: More Databases

For the More Curious: The Application Context

Challenge: Deleting Crimes

15. Implicit Intents

Adding Buttons

Adding a Suspect to the Model Layer

Using a Format String

Using Implicit Intents

Parts of an implicit intent

Sending a crime report

Asking Android for a contact

Checking for responding activities

Challenge: ShareCompat

Challenge: Another Implicit Intent

16. Taking Pictures with Intents

A Place for Your Photo

File Storage

Using FileProvider

Designating a picture location

Using a Camera Intent

Firing the intent

Scaling and Displaying Bitmaps

Declaring Features

Challenge: Detail Display

Challenge: Efficient Thumbnail Load

17. Two-Pane Master-Detail Interfaces

Adding Layout Flexibility

Modifying SingleFragmentActivity

Creating a layout with two fragment containers

Using an alias resource

Creating tablet alternatives

Activity: Fragment Boss

Fragment callback interfaces

For the More Curious: More on Determining Device Size

Challenge: Adding Swipe to Dismiss

18. Localization

Localizing Resources

Default resources

Checking string coverage using Translations Editor

Targeting a region

Configuration Qualifiers

Prioritizing alternative resources

Multiple qualifiers

Finding the best-matching resources

Testing Alternative Resources

Challenge: Localizing Dates

19. Accessibility

TalkBack

Explore by Touch

Linear navigation by swiping

Making Non-Text Elements Readable by TalkBack

Adding content descriptions

Making a widget focusable

Creating a Comparable Experience

Using labels to provide context

For the More Curious: Using Accessibility Scanner

Challenge: Improving the List

Challenge: Providing Enough Context for Data Entry

Challenge: Announcing Events

20. Data Binding and MVVM

Different Architectures: Why Bother?

Creating BeatBox

Simple data binding

Importing Assets

Getting At Assets

Wiring Up Assets for Use

Binding to Data

Creating a ViewModel

Binding to a ViewModel

Observable data

Accessing Assets

For the More Curious: More About Data Binding

Lambda expressions

More syntactic sugar

BindingAdapters

For the More Curious: Why Assets, Not Resources

For the More Curious: Non-Assets?

21. Unit Testing and Audio Playback

Creating a SoundPool

Loading Sounds

Playing Sounds

Test Dependencies

Creating a Test Class

Setting Up Your Test

Using mocked dependencies

Writing Tests

Testing object interactions

Data Binding Callbacks

Unloading Sounds

Rotation and Object Continuity

Retaining a fragment

Rotation and retained fragments

For the More Curious: Whether to Retain

For the More Curious: Espresso and Integration Testing

For the More Curious: Mocks and Testing

Challenge: Playback Speed Control

22. Styles and Themes

Color Resources

Styles

Style inheritance

Themes

Modifying the theme

Adding Theme Colors

Overriding Theme Attributes

Theme spelunking

Modifying Button Attributes

For the More Curious: More on Style Inheritance

For the More Curious: Accessing Theme Attributes

23. XML Drawables

Making Uniform Buttons

Shape Drawables

State List Drawables

Layer List Drawables

For the More Curious: Why Bother with XML Drawables?

For the More Curious: Mipmap Images

For the More Curious: 9-Patch Images

Challenge: Button Themes

24. More About Intents and Tasks

Setting Up NerdLauncher

Resolving an Implicit Intent

Creating Explicit Intents at Runtime

Tasks and the Back Stack

Switching between tasks

Starting a new task

Using NerdLauncher as a Home Screen

Challenge: Icons

For the More Curious: Processes vs Tasks

For the More Curious: Concurrent Documents

25. HTTP and Background Tasks

Creating PhotoGallery

Networking Basics

Asking permission to network

Using AsyncTask to Run on a Background Thread

You and Your Main Thread

Beyond the main thread

Fetching JSON from Flickr

Parsing JSON text

From AsyncTask Back to the Main Thread

Cleaning Up AsyncTasks

For the More Curious: More on AsyncTask

For the More Curious: Alternatives to AsyncTask

Challenge: Gson

Challenge: Paging

Challenge: Dynamically Adjusting the Number of Columns

26. Loopers, Handlers, and HandlerThread

Preparing RecyclerView to Display Images

Downloading Lots of Small Things

Communicating with the Main Thread

Assembling a Background Thread

Messages and Message Handlers

Message anatomy

Handler anatomy

Using handlers

Passing handlers

For the More Curious: AsyncTasks vs Threads

For the More Curious: Solving the Image Downloading Problem

For the More Curious: StrictMode

Challenge: Preloading and Caching

27. Search

Searching Flickr

Using SearchView

Responding to SearchView user interactions

Simple Persistence with Shared Preferences

Polishing Your App

Challenge: Polishing Your App Some More

28. Background Services

Creating an IntentService

What Services Are For

Safe background networking

Looking for New Results

Delayed Execution with AlarmManager

Being a good citizen: using alarms the right way

PendingIntent

Managing alarms with PendingIntent

Controlling Your Alarm

Notifications

Challenge: Notifications on Android Wear

For the More Curious: Service Details

What a service does (and does not do)

A service’s lifecycle

Non-sticky services

Sticky services

Bound services

For the More Curious: JobScheduler and JobServices

JobScheduler and the future of background work

Challenge: Using JobService on Lollipop

For the More Curious: Sync Adapters

29. Broadcast Intents

Regular Intents vs Broadcast Intents

Receiving a System Broadcast: Waking Up on Boot

Creating and registering a standalone receiver

Using receivers

Filtering Foreground Notifications

Sending broadcast intents

Creating and registering a dynamic receiver

Limiting broadcasts to your app using private permissions

Passing and receiving data with ordered broadcasts

Receivers and Long-Running Tasks

For the More Curious: Local Events

Using EventBus

Using RxJava

For the More Curious: Detecting the Visibility of Your Fragment

30. Browsing the Web and WebView

One Last Bit of Flickr Data

The Easy Way: Implicit Intents

The Harder Way: WebView

Using WebChromeClient to spruce things up

Proper Rotation with WebView

Dangers of handling configuration changes

For the More Curious: Injecting JavaScript Objects

For the More Curious: WebView Updates

Challenge: Using the Back Button for Browser History

Challenge: Supporting Non-HTTP Links

31. Custom Views and Touch Events

Setting Up the DragAndDraw Project

Creating a Custom View

Creating BoxDrawingView

Handling Touch Events

Tracking across motion events

Rendering Inside onDraw(Canvas)

Challenge: Saving State

Challenge: Rotating Boxes

32. Property Animation

Building the Scene

Simple Property Animation

View transformation properties

Using different interpolators

Color evaluation

Playing Animators Together

For the More Curious: Other Animation APIs

Legacy animation tools

Transitions

Challenges

33. Locations and Play Services

Locations and Libraries

Google Play Services

Creating Locatr

Play Services and Location Testing on Emulators

Mock location data

Building Out Locatr

Setting Up Google Play Services

Location permissions

Using Google Play Services

Flickr Geosearch

Getting a Location Fix

Asking for Permission at Runtime

Checking for permissions

Find and Display an Image

Challenge: Permissions Rationale

Challenge: Progress

34. Maps

Importing Play Services Maps

Mapping on Android

Getting a Maps API Key

Setting Up Your Map

Getting More Location Data

Working with Your Map

Drawing on the map

For the More Curious: Teams and API Keys

35. Material Design

Material Surfaces

Elevation and Z values

State list animators

Animation Tools

Circular reveal

Shared element transitions

View Components

Cards

Floating action buttons

Snackbars

More on Material Design

36. Afterword

The Final Challenge

Shameless Plugs

Thank You

Index