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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Update your Android studio skills and build modern Android applications using Java
Key Features
- Develop a comprehensive understanding of Android Jetpack
- Build your familiarity with Android architecture guidelines
- Study the design of Android applications and its user interfaces in-depth
Book Description
To meet the demands of the mobile market and keep its developer community ahead, Android rolls out frequent updates. Focussing on Android Jetpack libraries, this book teaches you how to build reliable Android applications using Java.
The book begins with the set-up of Android development and testing environments on Windows, macOS, and Linux. You will create an Android app and test it on an Android virtual device and a physical Android device. Next, you'll explore the features of Android Studio 3.6, Android 10, Android architecture, and Android Jetpack. Moving ahead, you'll cover touch-screen handling, cloud-based file storage, and foldable device support. The book then covers advanced topics such as views and widget implementation, multi-window support integration, and biometric authentication. Finally, you will learn to upload your app to the Google Play Console and handle the build process with Gradle.
By the end of this book, you'll have all the knowledge and skills needed to create modern Android applications.
What you will learn
- Design UI for Android applications using Android Studio Editor
- Build reliable apps with fewer coding errors using Android Jetpack
- Test Android applications on physical devices and emulators
- Explore unique ways to handle single- and multi-touch events
- Use Gesture libraries to implement gesture and pinch recognition systems
- Increase your app visibility with app links
Who this book is for
This book is ideal for application developers and programmers who want to leverage their Android skills using Java. A basic understanding of Java and Android SDK will help you to learn the concepts covered in this book more quickly.
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Seitenzahl: 975
Veröffentlichungsjahr: 2020
Ähnliche
Android Studio 3.6
Development Essentials
Java Edition
Android Studio 3.6 Development Essentials – Java Edition
ISBN-13: 978-1-951442-14-9
© 2020 Neil Smyth / Payload Media, Inc. All Rights Reserved.
This book is provided for personal use only. Unauthorized use, reproduction and/or distribution strictly prohibited. All rights reserved.
The content of this book is provided for informational purposes only. Neither the publisher nor the author offers any warranties or representation, express or implied, with regard to the accuracy of information contained in this book, nor do they accept any liability for any loss or damage arising from any errors or omissions.
This book contains trademarked terms that are used solely for editorial purposes and to the benefit of the respective trademark owner. The terms used within this book are not intended as infringement of any trademarks.
Rev: 1.0
Table of Contents
1. Introduction
1.1 Downloading the Code Samples
1.2 Feedback
1.3 Errata
2. Setting up an Android Studio Development Environment
2.1 System Requirements
2.2 Downloading the Android Studio Package
2.3 Installing Android Studio
2.3.1 Installation on Windows
2.3.2 Installation on macOS
2.3.3 Installation on Linux
2.4 The Android Studio Setup Wizard
2.5 Installing Additional Android SDK Packages
2.6 Making the Android SDK Tools Command-line Accessible
2.6.1 Windows 7
2.6.2 Windows 8.1
2.6.3 Windows 10
2.6.4 Linux
2.6.5 macOS
2.7 Android Studio Memory Management
2.8 Updating Android Studio and the SDK
2.9 Summary
3. Creating an Example Android App in Android Studio
3.1 About the Project
3.2 Creating a New Android Project
3.3 Creating an Activity
3.4 Defining the Project and SDK Settings
3.5 Modifying the Example Application
3.6 Modifying the User Interface
3.7 Reviewing the Layout and Resource Files
3.8 Adding Interaction
3.9 Summary
4. Creating an Android Virtual Device (AVD) in Android Studio
4.1 About Android Virtual Devices
4.2 Creating a New AVD
4.3 Starting the Emulator
4.4 Running the Application in the AVD
4.5 Stopping a Running Application
4.6 Supporting Dark Theme
4.7 AVD Command-line Creation
4.8 Android Virtual Device Configuration Files
4.9 Moving and Renaming an Android Virtual Device
4.10 Summary
5. Using and Configuring the Android Studio AVD Emulator
5.1 The Emulator Environment
5.2 The Emulator Toolbar Options
5.3 Working in Zoom Mode
5.4 Resizing the Emulator Window
5.5 Extended Control Options
5.5.1 Location
5.5.2 Displays
5.5.3 Cellular
5.5.4 Camera
5.5.5 Battery
5.5.6 Phone
5.5.7 Directional Pad
5.5.8 Microphone
5.5.9 Fingerprint
5.5.10 Virtual Sensors
5.5.11 Snapshots
5.5.12 Record and Playback
5.5.13 Google Play
5.5.14 Settings
5.5.15 Help
5.6 Working with Snapshots
5.7 Configuring Fingerprint Emulation
5.8 Summary
6. A Tour of the Android Studio User Interface
6.1 The Welcome Screen
6.2 The Main Window
6.3 The Tool Windows
6.4 Android Studio Keyboard Shortcuts
6.5 Switcher and Recent Files Navigation
6.6 Changing the Android Studio Theme
6.7 Summary
7. Testing Android Studio Apps on a Physical Android Device
7.1 An Overview of the Android Debug Bridge (ADB)
7.2 Enabling ADB on Android based Devices
7.2.1 macOS ADB Configuration
7.2.2 Windows ADB Configuration
7.2.3 Linux adb Configuration
7.3 Testing the adb Connection
7.4 Summary
8. The Basics of the Android Studio Code Editor
8.1 The Android Studio Editor
8.2 Splitting the Editor Window
8.3 Code Completion
8.4 Statement Completion
8.5 Parameter Information
8.6 Parameter Name Hints
8.7 Code Generation
8.8 Code Folding
8.9 Quick Documentation Lookup
8.10 Code Reformatting
8.11 Finding Sample Code
8.12 Summary
9. An Overview of the Android Architecture
9.1 The Android Software Stack
9.2 The Linux Kernel
9.3 Android Runtime – ART
9.4 Android Libraries
9.4.1 C/C++ Libraries
9.5 Application Framework
9.6 Applications
9.7 Summary
10. The Anatomy of an Android Application
10.1 Android Activities
10.2 Android Fragments
10.3 Android Intents
10.4 Broadcast Intents
10.5 Broadcast Receivers
10.6 Android Services
10.7 Content Providers
10.8 The Application Manifest
10.9 Application Resources
10.10 Application Context
10.11 Summary
11. An Overview of Android View Binding
11.1 Find View by ID
11.2 View Bindings
11.3 Converting the AndroidSample Project
11.4 Enabling View Binding
11.5 Using View Bindings
11.6 Choosing an Option
11.7 Summary
12. Understanding Android Application and Activity Lifecycles
12.1 Android Applications and Resource Management
12.2 Android Process States
12.2.1 Foreground Process
12.2.2 Visible Process
12.2.3 Service Process
12.2.4 Background Process
12.2.5 Empty Process
12.3 Inter-Process Dependencies
12.4 The Activity Lifecycle
12.5 The Activity Stack
12.6 Activity States
12.7 Configuration Changes
12.8 Handling State Change
12.9 Summary
13. Handling Android Activity State Changes
13.1 New vs. Old Lifecycle Techniques
13.2 The Activity and Fragment Classes
13.3 Dynamic State vs. Persistent State
13.4 The Android Lifecycle Methods
13.5 Lifetimes
13.6 Foldable Devices and Multi-Resume
13.7 Disabling Configuration Change Restarts
13.8 Lifecycle Method Limitations
13.9 Summary
14. Android Activity State Changes by Example
14.1 Creating the State Change Example Project
14.2 Designing the User Interface
14.3 Overriding the Activity Lifecycle Methods
14.4 Filtering the Logcat Panel
14.5 Running the Application
14.6 Experimenting with the Activity
14.7 Summary
15. Saving and Restoring the State of an Android Activity
15.1 Saving Dynamic State
15.2 Default Saving of User Interface State
15.3 The Bundle Class
15.4 Saving the State
15.5 Restoring the State
15.6 Testing the Application
15.7 Summary
16. Understanding Android Views, View Groups and Layouts
16.1 Designing for Different Android Devices
16.2 Views and View Groups
16.3 Android Layout Managers
16.4 The View Hierarchy
16.5 Creating User Interfaces
16.6 Summary
17. A Guide to the Android Studio Layout Editor Tool
17.1 Basic vs. Empty Activity Templates
17.2 The Android Studio Layout Editor
17.3 Design Mode
17.4 The Palette
17.5 Design Mode and Layout Views
17.6 Code Mode
17.7 Split Mode
17.8 Setting Attributes
17.9 Converting Views
17.10 Displaying Sample Data
17.11 Creating a Custom Device Definition
17.12 Changing the Current Device
17.13 Multi Preview
17.14 Summary
18. A Guide to the Android ConstraintLayout
18.1 How ConstraintLayout Works
18.1.1 Constraints
18.1.2 Margins
18.1.3 Opposing Constraints
18.1.4 Constraint Bias
18.1.5 Chains
18.1.6 Chain Styles
18.2 Baseline Alignment
18.3 Working with Guidelines
18.4 Configuring Widget Dimensions
18.5 Working with Barriers
18.6 Ratios
18.7 ConstraintLayout Advantages
18.8 ConstraintLayout Availability
18.9 Summary
19. A Guide to using ConstraintLayout in Android Studio
19.1 Design and Layout Views
19.2 Autoconnect Mode
19.3 Inference Mode
19.4 Manipulating Constraints Manually
19.5 Adding Constraints in the Inspector
19.6 Viewing Constraints in the Attributes Window
19.7 Deleting Constraints
19.8 Adjusting Constraint Bias
19.9 Understanding ConstraintLayout Margins
19.10 The Importance of Opposing Constraints and Bias
19.11 Configuring Widget Dimensions
19.12 Adding Guidelines
19.13 Adding Barriers
19.14 Widget Group Alignment and Distribution
19.15 Converting other Layouts to ConstraintLayout
19.16 Summary
20. Working with ConstraintLayout Chains and Ratios in Android Studio
20.1 Creating a Chain
20.2 Changing the Chain Style
20.3 Spread Inside Chain Style
20.4 Packed Chain Style
20.5 Packed Chain Style with Bias
20.6 Weighted Chain
20.7 Working with Ratios
20.8 Summary
21. An Android Studio Layout Editor ConstraintLayout Tutorial
21.1 An Android Studio Layout Editor Tool Example
21.2 Creating a New Activity
21.3 Preparing the Layout Editor Environment
21.4 Adding the Widgets to the User Interface
21.5 Adding the Constraints
21.6 Testing the Layout
21.7 Using the Layout Inspector
21.8 Summary
22. Manual XML Layout Design in Android Studio
22.1 Manually Creating an XML Layout
22.2 Manual XML vs. Visual Layout Design
22.3 Summary
23. Managing Constraints using Constraint Sets
23.1 Java Code vs. XML Layout Files
23.2 Creating Views
23.3 View Attributes
23.4 Constraint Sets
23.4.1 Establishing Connections
23.4.2 Applying Constraints to a Layout
23.4.3 Parent Constraint Connections
23.4.4 Sizing Constraints
23.4.5 Constraint Bias
23.4.6 Alignment Constraints
23.4.7 Copying and Applying Constraint Sets
23.4.8 ConstraintLayout Chains
23.4.9 Guidelines
23.4.10 Removing Constraints
23.4.11 Scaling
23.4.12 Rotation
23.5 Summary
24. An Android ConstraintSet Tutorial
24.1 Creating the Example Project in Android Studio
24.2 Adding Views to an Activity
24.3 Setting View Attributes
24.4 Creating View IDs
24.5 Configuring the Constraint Set
24.6 Adding the EditText View
24.7 Converting Density Independent Pixels (dp) to Pixels (px)
24.8 Summary
25. A Guide to using Apply Changes in Android Studio
25.1 Introducing Apply Changes
25.2 Understanding Apply Changes Options
25.3 Using Apply Changes
25.4 Configuring Apply Changes Fallback Settings
25.5 An Apply Changes Tutorial
25.6 Using Apply Code Changes
25.7 Using Apply Changes and Restart Activity
25.8 Using Run App
25.9 Summary
26. An Overview and Example of Android Event Handling
26.1 Understanding Android Events
26.2 Using the android:onClick Resource
26.3 Event Listeners and Callback Methods
26.4 An Event Handling Example
26.5 Designing the User Interface
26.6 The Event Listener and Callback Method
26.7 Consuming Events
26.8 Summary
27. Android Touch and Multi-touch Event Handling
27.1 Intercepting Touch Events
27.2 The MotionEvent Object
27.3 Understanding Touch Actions
27.4 Handling Multiple Touches
27.5 An Example Multi-Touch Application
27.6 Designing the Activity User Interface
27.7 Implementing the Touch Event Listener
27.8 Running the Example Application
27.9 Summary
28. Detecting Common Gestures using the Android Gesture Detector Class
28.1 Implementing Common Gesture Detection
28.2 Creating an Example Gesture Detection Project
28.3 Implementing the Listener Class
28.4 Creating the GestureDetectorCompat Instance
28.5 Implementing the onTouchEvent() Method
28.6 Testing the Application
28.7 Summary
29. Implementing Custom Gesture and Pinch Recognition on Android
29.1 The Android Gesture Builder Application
29.2 The GestureOverlayView Class
29.3 Detecting Gestures
29.4 Identifying Specific Gestures
29.5 Installing and Running the Gesture Builder Application
29.6 Creating a Gestures File
29.7 Creating the Example Project
29.8 Extracting the Gestures File from the SD Card
29.9 Adding the Gestures File to the Project
29.10 Designing the User Interface
29.11 Loading the Gestures File
29.12 Registering the Event Listener
29.13 Implementing the onGesturePerformed Method
29.14 Testing the Application
29.15 Configuring the GestureOverlayView
29.16 Intercepting Gestures
29.17 Detecting Pinch Gestures
29.18 A Pinch Gesture Example Project
29.19 Summary
30. An Introduction to Android Fragments
30.1 What is a Fragment?
30.2 Creating a Fragment
30.3 Adding a Fragment to an Activity using the Layout XML File
30.4 Adding and Managing Fragments in Code
30.5 Handling Fragment Events
30.6 Implementing Fragment Communication
30.7 Summary
31. Using Fragments in Android Studio - An Example
31.1 About the Example Fragment Application
31.2 Creating the Example Project
31.3 Creating the First Fragment Layout
31.4 Creating the First Fragment Class
31.5 Creating the Second Fragment Layout
31.6 Adding the Fragments to the Activity
31.7 Making the Toolbar Fragment Talk to the Activity
31.8 Making the Activity Talk to the Text Fragment
31.9 Testing the Application
31.10 Summary
32. Modern Android App Architecture with Jetpack
32.1 What is Android Jetpack?
32.2 The “Old” Architecture
32.3 Modern Android Architecture
32.4 The ViewModel Component
32.5 The LiveData Component
32.6 ViewModel Saved State
32.7 LiveData and Data Binding
32.8 Android Lifecycles
32.9 Repository Modules
32.10 Summary
33. An Android Jetpack ViewModel Tutorial
33.1 About the Project
33.2 Creating the ViewModel Example Project
33.3 Reviewing the Project
33.3.1 The Main Activity
33.3.2 The Content Fragment
33.3.3 The ViewModel
33.4 Designing the Fragment Layout
33.5 Implementing the View Model
33.6 Associating the Fragment with the View Model
33.7 Modifying the Fragment
33.8 Accessing the ViewModel Data
33.9 Testing the Project
33.10 Summary
34. An Android Jetpack LiveData Tutorial
34.1 LiveData - A Recap
34.2 Adding LiveData to the ViewModel
34.3 Implementing the Observer
34.4 Summary
35. An Overview of Android Jetpack Data Binding
35.1 An Overview of Data Binding
35.2 The Key Components of Data Binding
35.2.1 The Project Build Configuration
35.2.2 The Data Binding Layout File
35.2.3 The Layout File Data Element
35.2.4 The Binding Classes
35.2.5 Data Binding Variable Configuration
35.2.6 Binding Expressions (One-Way)
35.2.7 Binding Expressions (Two-Way)
35.2.8 Event and Listener Bindings
35.3 Summary
36. An Android Jetpack Data Binding Tutorial
36.1 Removing the Redundant Code
36.2 Enabling Data Binding
36.3 Adding the Layout Element
36.4 Adding the Data Element to Layout File
36.5 Working with the Binding Class
36.6 Assigning the ViewModel Instance to the Data Binding Variable
36.7 Adding Binding Expressions
36.8 Adding the Conversion Method
36.9 Adding a Listener Binding
36.10 Testing the App
36.11 Summary
37. An Android ViewModel Saved State Tutorial
37.1 Understanding ViewModel State Saving
37.2 Implementing ViewModel State Saving
37.3 Saving and Restoring State
37.4 Adding Saved State Support to the ViewModelDemo Project
37.5 Summary
38. Working with Android Lifecycle-Aware Components
38.1 Lifecycle Awareness
38.2 Lifecycle Owners
38.3 Lifecycle Observers
38.4 Lifecycle States and Events
38.5 Summary
39. An Android Jetpack Lifecycle Awareness Tutorial
39.1 Creating the Example Lifecycle Project
39.2 Creating a Lifecycle Observer
39.3 Adding the Observer
39.4 Testing the Observer
39.5 Creating a Lifecycle Owner
39.6 Testing the Custom Lifecycle Owner
39.7 Summary
40. An Overview of the Navigation Architecture Component
40.1 Understanding Navigation
40.2 Declaring a Navigation Host
40.3 The Navigation Graph
40.4 Accessing the Navigation Controller
40.5 Triggering a Navigation Action
40.6 Passing Arguments
40.7 Summary
41. An Android Jetpack Navigation Component Tutorial
41.1 Creating the NavigationDemo Project
41.2 Adding Navigation to the Build Configuration
41.3 Creating the Navigation Graph Resource File
41.4 Declaring a Navigation Host
41.5 Adding Navigation Destinations
41.6 Designing the Destination Fragment Layouts
41.7 Adding an Action to the Navigation Graph
41.8 Implement the OnFragmentInteractionListener
41.9 Triggering the Action
41.10 Passing Data Using Safeargs
41.11 Summary
42. Creating and Managing Overflow Menus on Android
42.1 The Overflow Menu
42.2 Creating an Overflow Menu
42.3 Displaying an Overflow Menu
42.4 Responding to Menu Item Selections
42.5 Creating Checkable Item Groups
42.6 Menus and the Android Studio Menu Editor
42.7 Creating the Example Project
42.8 Designing the Menu
42.9 Modifying the onOptionsItemSelected() Method
42.10 Testing the Application
42.11 Summary
43. Animating User Interfaces with the Android Transitions Framework
43.1 Introducing Android Transitions and Scenes
43.2 Using Interpolators with Transitions
43.3 Working with Scene Transitions
43.4 Custom Transitions and TransitionSets in Code
43.5 Custom Transitions and TransitionSets in XML
43.6 Working with Interpolators
43.7 Creating a Custom Interpolator
43.8 Using the beginDelayedTransition Method
43.9 Summary
44. An Android Transition Tutorial using beginDelayedTransition
44.1 Creating the Android Studio TransitionDemo Project
44.2 Preparing the Project Files
44.3 Implementing beginDelayedTransition Animation
44.4 Customizing the Transition
44.5 Summary
45. Implementing Android Scene Transitions – A Tutorial
45.1 An Overview of the Scene Transition Project
45.2 Creating the Android Studio SceneTransitions Project
45.3 Identifying and Preparing the Root Container
45.4 Designing the First Scene
45.5 Designing the Second Scene
45.6 Entering the First Scene
45.7 Loading Scene 2
45.8 Implementing the Transitions
45.9 Adding the Transition File
45.10 Loading and Using the Transition Set
45.11 Configuring Additional Transitions
45.12 Summary
46. Working with the Floating Action Button and Snackbar
46.1 The Material Design
46.2 The Design Library
46.3 The Floating Action Button (FAB)
46.4 The Snackbar
46.5 Creating the Example Project
46.6 Reviewing the Project
46.7 Removing Navigation Features
46.8 Changing the Floating Action Button
46.9 Adding the ListView to the Content Layout
46.10 Adding Items to the ListView
46.11 Adding an Action to the Snackbar
46.12 Summary
47. Creating a Tabbed Interface using the TabLayout Component
47.1 An Introduction to the ViewPager
47.2 An Overview of the TabLayout Component
47.3 Creating the TabLayoutDemo Project
47.4 Creating the First Fragment
47.5 Duplicating the Fragments
47.6 Adding the TabLayout and ViewPager
47.7 Creating the Pager Adapter
47.8 Performing the Initialization Tasks
47.9 Testing the Application
47.10 Customizing the TabLayout
47.11 Displaying Icon Tab Items
47.12 Summary
48. Working with the RecyclerView and CardView Widgets
48.1 An Overview of the RecyclerView
48.2 An Overview of the CardView
48.3 Summary
49. An Android RecyclerView and CardView Tutorial
49.1 Creating the CardDemo Project
49.2 Modifying the Basic Activity Project
49.3 Designing the CardView Layout
49.4 Adding the RecyclerView
49.5 Creating the RecyclerView Adapter
49.6 Adding the Image Files
49.7 Initializing the RecyclerView Component
49.8 Testing the Application
49.9 Responding to Card Selections
49.10 Summary
50. A Layout Editor Sample Data Tutorial
50.1 Adding Sample Data to a Project
50.2 Using Custom Sample Data
50.3 Summary
51. Working with the AppBar and Collapsing Toolbar Layouts
51.1 The Anatomy of an AppBar
51.2 The Example Project
51.3 Coordinating the RecyclerView and Toolbar
51.4 Introducing the Collapsing Toolbar Layout
51.5 Changing the Title and Scrim Color
51.6 Summary
52. An Android Studio Master/Detail Flow Tutorial
52.1 The Master/Detail Flow
52.2 Creating a Master/Detail Flow Activity
52.3 The Anatomy of the Master/Detail Flow Template
52.4 Modifying the Master/Detail Flow Template
52.5 Changing the Content Model
52.6 Changing the Detail Pane
52.7 Modifying the WebsiteDetailFragment Class
52.8 Modifying the WebsiteListActivity Class
52.9 Adding Manifest Permissions
52.10 Running the Application
52.11 Summary
53. An Overview of Android Intents
53.1 An Overview of Intents
53.2 Explicit Intents
53.3 Returning Data from an Activity
53.4 Implicit Intents
53.5 Using Intent Filters
53.6 Checking Intent Availability
53.7 Summary
54. Android Explicit Intents – A Worked Example
54.1 Creating the Explicit Intent Example Application
54.2 Designing the User Interface Layout for MainActivity
54.3 Creating the Second Activity Class
54.4 Designing the User Interface Layout for ActivityB
54.5 Reviewing the Application Manifest File
54.6 Creating the Intent
54.7 Extracting Intent Data
54.8 Launching ActivityB as a Sub-Activity
54.9 Returning Data from a Sub-Activity
54.10 Testing the Application
54.11 Summary
55. Android Implicit Intents – A Worked Example
55.1 Creating the Android Studio Implicit Intent Example Project
55.2 Designing the User Interface
55.3 Creating the Implicit Intent
55.4 Adding a Second Matching Activity
55.5 Adding the Web View to the UI
55.6 Obtaining the Intent URL
55.7 Modifying the MyWebView Project Manifest File
55.8 Installing the MyWebView Package on a Device
55.9 Testing the Application
55.10 Summary
56. Android Broadcast Intents and Broadcast Receivers
56.1 An Overview of Broadcast Intents
56.2 An Overview of Broadcast Receivers
56.3 Obtaining Results from a Broadcast
56.4 Sticky Broadcast Intents
56.5 The Broadcast Intent Example
56.6 Creating the Example Application
56.7 Creating and Sending the Broadcast Intent
56.8 Creating the Broadcast Receiver
56.9 Registering the Broadcast Receiver
56.10 Testing the Broadcast Example
56.11 Listening for System Broadcasts
56.12 Summary
57. A Basic Overview of Threads and AsyncTasks
57.1 An Overview of Threads
57.2 The Application Main Thread
57.3 Thread Handlers
57.4 A Basic AsyncTask Example
57.5 Subclassing AsyncTask
57.6 Testing the App
57.7 Canceling a Task
57.8 Summary
58. An Overview of Android Started and Bound Services
58.1 Started Services
58.2 Intent Service
58.3 Bound Service
58.4 The Anatomy of a Service
58.5 Controlling Destroyed Service Restart Options
58.6 Declaring a Service in the Manifest File
58.7 Starting a Service Running on System Startup
58.8 Summary
59. Implementing an Android Started Service – A Worked Example
59.1 Creating the Example Project
59.2 Creating the Service Class
59.3 Adding the Service to the Manifest File
59.4 Starting the Service
59.5 Testing the IntentService Example
59.6 Using the Service Class
59.7 Creating the New Service
59.8 Modifying the User Interface
59.9 Running the Application
59.10 Creating an AsyncTask for Service Tasks
59.11 Summary
60. Android Local Bound Services – A Worked Example
60.1 Understanding Bound Services
60.2 Bound Service Interaction Options
60.3 An Android Studio Local Bound Service Example
60.4 Adding a Bound Service to the Project
60.5 Implementing the Binder
60.6 Binding the Client to the Service
60.7 Completing the Example
60.8 Testing the Application
60.9 Summary
61. Android Remote Bound Services – A Worked Example
61.1 Client to Remote Service Communication
61.2 Creating the Example Application
61.3 Designing the User Interface
61.4 Implementing the Remote Bound Service
61.5 Configuring a Remote Service in the Manifest File
61.6 Launching and Binding to the Remote Service
61.7 Sending a Message to the Remote Service
61.8 Summary
62. An Android Notifications Tutorial
62.1 An Overview of Notifications
62.2 Creating the NotifyDemo Project
62.3 Designing the User Interface
62.4 Creating the Second Activity
62.5 Creating a Notification Channel
62.6 Creating and Issuing a Basic Notification
62.7 Launching an Activity from a Notification
62.8 Adding Actions to a Notification
62.9 Bundled Notifications
62.10 Summary
63. An Android Direct Reply Notification Tutorial
63.1 Creating the DirectReply Project
63.2 Designing the User Interface
63.3 Creating the Notification Channel
63.4 Building the RemoteInput Object
63.5 Creating the PendingIntent
63.6 Creating the Reply Action
63.7 Receiving Direct Reply Input
63.8 Updating the Notification
63.9 Summary
64. Foldable Devices and Multi-Window Support
64.1 Foldables and Multi-Window Support
64.2 Using a Foldable Emulator
64.3 Entering Multi-Window Mode
64.4 Enabling and using Freeform Support
64.5 Checking for Freeform Support
64.6 Enabling Multi-Window Support in an App
64.7 Specifying Multi-Window Attributes
64.8 Detecting Multi-Window Mode in an Activity
64.9 Receiving Multi-Window Notifications
64.10 Launching an Activity in Multi-Window Mode
64.11 Configuring Freeform Activity Size and Position
64.12 Summary
65. An Overview of Android SQLite Databases
65.1 Understanding Database Tables
65.2 Introducing Database Schema
65.3 Columns and Data Types
65.4 Database Rows
65.5 Introducing Primary Keys
65.6 What is SQLite?
65.7 Structured Query Language (SQL)
65.8 Trying SQLite on an Android Virtual Device (AVD)
65.9 The Android Room Persistence Library
65.10 Summary
66. The Android Room Persistence Library
66.1 Revisiting Modern App Architecture
66.2 Key Elements of Room Database Persistence
66.2.1 Repository
66.2.2 Room Database
66.2.3 Data Access Object (DAO)
66.2.4 Entities
66.2.5 SQLite Database
66.3 Understanding Entities
66.4 Data Access Objects
66.5 The Room Database
66.6 The Repository
66.7 In-Memory Databases
66.8 Summary
67. An Android TableLayout and TableRow Tutorial
67.1 The TableLayout and TableRow Layout Views
67.2 Creating the Room Database Project
67.3 Converting to a LinearLayout
67.4 Adding the TableLayout to the User Interface
67.5 Configuring the TableRows
67.6 Adding the Button Bar to the Layout
67.7 Adding the RecyclerView
67.8 Adjusting the Layout Margins
67.9 Summary
68. An Android Room Database and Repository Tutorial
68.1 About the RoomDemo Project
68.2 Modifying the Build Configuration
68.3 Building the Entity
68.4 Creating the Data Access Object
68.5 Adding the Room Database
68.6 Adding the Repository
68.7 Modifying the ViewModel
68.8 Creating the Product Item Layout
68.9 Adding the RecyclerView Adapter
68.10 Preparing the Main Fragment
68.11 Adding the Button Listeners
68.12 Adding LiveData Observers
68.13 Initializing the RecyclerView
68.14 Testing the RoomDemo App
68.15 Summary
69. Accessing Cloud Storage using the Android Storage Access Framework
69.1 The Storage Access Framework
69.2 Working with the Storage Access Framework
69.3 Filtering Picker File Listings
69.4 Handling Intent Results
69.5 Reading the Content of a File
69.6 Writing Content to a File
69.7 Deleting a File
69.8 Gaining Persistent Access to a File
69.9 Summary
70. An Android Storage Access Framework Example
70.1 About the Storage Access Framework Example
70.2 Creating the Storage Access Framework Example
70.3 Designing the User Interface
70.4 Declaring Request Codes
70.5 Creating a New Storage File
70.6 The onActivityResult() Method
70.7 Saving to a Storage File
70.8 Opening and Reading a Storage File
70.9 Testing the Storage Access Application
70.10 Summary
71. Implementing Video Playback on Android using the VideoView and MediaController Classes
71.1 Introducing the Android VideoView Class
71.2 Introducing the Android MediaController Class
71.3 Creating the Video Playback Example
71.4 Designing the VideoPlayer Layout
71.5 Downloading the Video File
71.6 Configuring the VideoView
71.7 Adding the MediaController to the Video View
71.8 Setting up the onPreparedListener
71.9 Summary
72. Android Picture-in-Picture Mode
72.1 Picture-in-Picture Features
72.2 Enabling Picture-in-Picture Mode
72.3 Configuring Picture-in-Picture Parameters
72.4 Entering Picture-in-Picture Mode
72.5 Detecting Picture-in-Picture Mode Changes
72.6 Adding Picture-in-Picture Actions
72.7 Summary
73. An Android Picture-in-Picture Tutorial
73.1 Adding Picture-in-Picture Support to the Manifest
73.2 Adding a Picture-in-Picture Button
73.3 Entering Picture-in-Picture Mode
73.4 Detecting Picture-in-Picture Mode Changes
73.5 Adding a Broadcast Receiver
73.6 Adding the PiP Action
73.7 Testing the Picture-in-Picture Action
73.8 Summary
74. Making Runtime Permission Requests in Android
74.1 Understanding Normal and Dangerous Permissions
74.2 Creating the Permissions Example Project
74.3 Checking for a Permission
74.4 Requesting Permission at Runtime
74.5 Providing a Rationale for the Permission Request
74.6 Testing the Permissions App
74.7 Summary
75. Android Audio Recording and Playback using MediaPlayer and MediaRecorder
75.1 Playing Audio
75.2 Recording Audio and Video using the MediaRecorder Class
75.3 About the Example Project
75.4 Creating the AudioApp Project
75.5 Designing the User Interface
75.6 Checking for Microphone Availability
75.7 Performing the Activity Initialization
75.8 Implementing the recordAudio() Method
75.9 Implementing the stopAudio() Method
75.10 Implementing the playAudio() method
75.11 Configuring and Requesting Permissions
75.12 Testing the Application
75.13 Summary
76. Working with the Google Maps Android API in Android Studio
76.1 The Elements of the Google Maps Android API
76.2 Creating the Google Maps Project
76.3 Obtaining Your Developer Signature
76.4 Adding the Apache HTTP Legacy Library Requirement
76.5 Testing the Application
76.6 Understanding Geocoding and Reverse Geocoding
76.7 Adding a Map to an Application
76.8 Requesting Current Location Permission
76.9 Displaying the User’s Current Location
76.10 Changing the Map Type
76.11 Displaying Map Controls to the User
76.12 Handling Map Gesture Interaction
76.12.1 Map Zooming Gestures
76.12.2 Map Scrolling/Panning Gestures
76.12.3 Map Tilt Gestures
76.12.4 Map Rotation Gestures
76.13 Creating Map Markers
76.14 Controlling the Map Camera
76.15 Summary
77. Printing with the Android Printing Framework
77.1 The Android Printing Architecture
77.2 The Print Service Plugins
77.3 Google Cloud Print
77.4 Printing to Google Drive
77.5 Save as PDF
77.6 Printing from Android Devices
77.7 Options for Building Print Support into Android Apps
77.7.1 Image Printing
77.7.2 Creating and Printing HTML Content
77.7.3 Printing a Web Page
77.7.4 Printing a Custom Document
77.8 Summary
78. An Android HTML and Web Content Printing Example
78.1 Creating the HTML Printing Example Application
78.2 Printing Dynamic HTML Content
78.3 Creating the Web Page Printing Example
78.4 Removing the Floating Action Button
78.5 Removing Navigation Features
78.6 Designing the User Interface Layout
78.7 Loading the Web Page into the WebView
78.8 Adding the Print Menu Option
78.9 Summary
79. A Guide to Android Custom Document Printing
79.1 An Overview of Android Custom Document Printing
79.1.1 Custom Print Adapters
79.2 Preparing the Custom Document Printing Project
79.3 Creating the Custom Print Adapter
79.4 Implementing the onLayout() Callback Method
79.5 Implementing the onWrite() Callback Method
79.6 Checking a Page is in Range
79.7 Drawing the Content on the Page Canvas
79.8 Starting the Print Job
79.9 Testing the Application
79.10 Summary
80. An Introduction to Android App Links
80.1 An Overview of Android App Links
80.2 App Link Intent Filters
80.3 Handling App Link Intents
80.4 Associating the App with a Website
80.5 Summary
81. An Android Studio App Links Tutorial
81.1 About the Example App
81.2 The Database Schema
81.3 Loading and Running the Project
81.4 Adding the URL Mapping
81.5 Adding the Intent Filter
81.6 Adding Intent Handling Code
81.7 Testing the App Link
81.8 Associating an App Link with a Web Site
81.9 Summary
82. A Guide to the Android Studio Profiler
82.1 Accessing the Android Profiler
82.2 Enabling Advanced Profiling
82.3 The Android Profiler Tool Window
82.4 The Sessions Panel
82.5 The CPU Profiler
82.6 Memory Profiler
82.7 Network Profiler
82.8 Energy Profiler
82.9 Summary
83. An Android Biometric Authentication Tutorial
83.1 An Overview of Biometric Authentication
83.2 Creating the Biometric Authentication Project
83.3 Configuring Device Fingerprint Authentication
83.4 Adding the Biometric Permission to the Manifest File
83.5 Designing the User Interface
83.6 Adding a Toast Convenience Method
83.7 Checking the Security Settings
83.8 Configuring the Authentication Callbacks
83.9 Adding the CancellationSignal
83.10 Starting the Biometric Prompt
83.11 Testing the Project
83.12 Summary
84. Creating, Testing and Uploading an Android App Bundle
84.1 The Release Preparation Process
84.2 Android App Bundles
84.3 Register for a Google Play Developer Console Account
84.4 Configuring the App in the Console
84.5 Enabling Google Play App Signing
84.6 Creating a Keystore File
84.7 Creating the Android App Bundle
84.8 Generating Test APK Files
84.9 Uploading the App Bundle to the Google Play Developer Console
84.10 Exploring the App Bundle
84.11 Managing Testers
84.12 Uploading New App Bundle Revisions
84.13 Analyzing the App Bundle File
84.14 Enabling Google Play Signing for an Existing App
84.15 Summary
85. An Overview of Android Dynamic Feature Modules
85.1 An Overview of Dynamic Feature Modules
85.2 Dynamic Feature Module Architecture
85.3 Creating a Dynamic Feature Module
85.4 Converting an Existing Module for Dynamic Delivery
85.5 Working with Dynamic Feature Modules
85.6 Handling Large Dynamic Feature Modules
85.7 Summary
86. An Android Studio Dynamic Feature Tutorial
86.1 Creating the DynamicFeature Project
86.2 Adding Dynamic Feature Support to the Project
86.3 Designing the Base Activity User Interface
86.4 Adding the Dynamic Feature Module
86.5 Reviewing the Dynamic Feature Module
86.6 Adding the Dynamic Feature Activity
86.7 Implementing the launchIntent() Method
86.8 Uploading the App Bundle for Testing
86.9 Implementing the installFeature() Method
86.10 Adding the Update Listener
86.11 Handling Large Downloads
86.12 Using Deferred Installation
86.13 Removing a Dynamic Module
86.14 Summary
87. An Overview of Gradle in Android Studio
87.1 An Overview of Gradle
87.2 Gradle and Android Studio
87.2.1 Sensible Defaults
87.2.2 Dependencies
87.2.3 Build Variants
87.2.4 Manifest Entries
87.2.5 APK Signing
87.2.6 ProGuard Support
87.3 The Top-level Gradle Build File
87.4 Module Level Gradle Build Files
87.5 Configuring Signing Settings in the Build File
87.6 Running Gradle Tasks from the Command-line
87.7 Summary
Index
1. Introduction
In 2018 Google introduced Android Jetpack to the developer community. Designed to make it quicker and easier to develop modern and reliable Android apps, Jetpack consists of a set of tools, libraries and architectural guidelines. The main elements of Android Jetpack consist of the Android Studio Integrated Development Environment (IDE), the Android Architecture Components and the Modern App Architecture Guidelines, all of which are covered in this latest edition of Android Studio Development Essentials.
Fully updated for Android Studio 3.6 and Android 10 (Q), the goal of this book is to teach the skills necessary to develop Android based applications using the Java programming language.
Beginning with the basics, this book provides an outline of the steps necessary to set up an Android development and testing environment. An overview of Android Studio is included covering areas such as tool windows, the code editor and the Layout Editor tool. An introduction to the architecture of Android is followed by an in-depth look at the design of Android applications and user interfaces using the Android Studio environment.
Chapters are also included covering the Android Architecture Components including view models, lifecycle management, Room database access, app navigation, live data and data binding.
More advanced topics such as intents are also covered, as are touch screen handling, gesture recognition, and the recording and playback of audio. This edition of the book also covers printing, transitions, cloud-based file storage and foldable device support.
The concepts of material design are also covered in detail, including the use of floating action buttons, Snackbars, tabbed interfaces, card views, navigation drawers and collapsing toolbars.
In addition to covering general Android development techniques, the book also includes Google Play specific topics such as implementing maps using the Google Maps Android API, and submitting apps to the Google Play Developer Console.
Other key features of Android Studio 3.6 and Android 10 are also covered in detail including the Layout Editor, the ConstraintLayout and ConstraintSet classes, view binding, constraint chains, barriers and direct reply notifications.
Chapters also cover advanced features of Android Studio such as App Links, Dynamic Delivery, the Android Studio Profiler and Gradle build configuration.
Assuming you already have some Java programming experience, are ready to download Android Studio and the Android SDK, have access to a Windows, Mac or Linux system and ideas for some apps to develop, you are ready to get started.
1.1 Downloading the Code Samples
The source code and Android Studio project files for the examples contained in this book are available for download at:
https://www.ebookfrenzy.com/retail/androidstudio36/index.php
The steps to load a project from the code samples into Android Studio are as follows:
1. From the Welcome to Android Studio dialog, select the Open an existing Android Studio project option.
2. In the project selection dialog, navigate to and select the folder containing the project to be imported and click on OK.
1.2 Feedback
We want you to be satisfied with your purchase of this book. If you find any errors in the book, or have any comments, questions or concerns please contact us at [email protected].
1.3 Errata
While we make every effort to ensure the accuracy of the content of this book, it is inevitable that a book covering a subject area of this size and complexity may include some errors and oversights. Any known issues with the book will be outlined, together with solutions, at the following URL:
https://www.ebookfrenzy.com/errata/androidstudio36.html
In the event that you find an error not listed in the errata, please let us know by emailing our technical support team at [email protected]. They are there to help you and will work to resolve any problems you may encounter.
2. Setting up an Android Studio Development Environment
Before any work can begin on the development of an Android application, the first step is to configure a computer system to act as the development platform. This involves a number of steps consisting of installing the Android Studio Integrated Development Environment (IDE) which also includes the Android Software Development Kit (SDK) and OpenJDK Java development environment.
This chapter will cover the steps necessary to install the requisite components for Android application development on Windows, macOS and Linux based systems.
2.1 System Requirements
Android application development may be performed on any of the following system types:
•Windows 7/8/10 (32-bit or 64-bit though the Android emulator will only run on 64-bit systems)
•macOS 10.10 or later (Intel based systems only)
•ChromeOS device with Intel i5 or higher and minimum 8GB of RAM
•Linux systems with version 2.19 or later of GNU C Library (glibc)
•Minimum of 4GB of RAM (8GB is preferred)
•Approximately 4GB of available disk space
•1280 x 800 minimum screen resolution
2.2 Downloading the Android Studio Package
Most of the work involved in developing applications for Android will be performed using the Android Studio environment. The content and examples in this book were created based on Android Studio version 3.6 using the Android 10.0 (Q) API 29 SDK which, at the time writing are the current versions.
Android Studio is, however, subject to frequent updates so a newer version may have been released since this book was published.
The latest release of Android Studio may be downloaded from the primary download page which can be found at the following URL:
https://developer.android.com/studio/index.html
If this page provides instructions for downloading a newer version of Android Studio it is important to note that there may be some minor differences between this book and the software. A web search for Android Studio 3.6 should provide the option to download the older version in the event that these differences become a problem. Alternatively, visit the following web page to find Android Studio 3.6 in the archives:
https://developer.android.com/studio/archive
2.3 Installing Android Studio
Once downloaded, the exact steps to install Android Studio differ depending on the operating system on which the installation is being performed.
2.3.1 Installation on Windows
Locate the downloaded Android Studio installation executable file (named android-studio-ide-<version>-windows.exe) in a Windows Explorer window and double-click on it to start the installation process, clicking the Yes button in the User Account Control dialog if it appears.
Once the Android Studio setup wizard appears, work through the various screens to configure the installation to meet your requirements in terms of the file system location into which Android Studio should be installed and whether or not it should be made available to other users of the system. When prompted to select the components to install, make sure that the Android Studio and Android Virtual Device options are all selected.
Although there are no strict rules on where Android Studio should be installed on the system, the remainder of this book will assume that the installation was performed into C:\Program Files\Android\Android Studio and that the Android SDK packages have been installed into the user’s AppData\Local\Android\sdk sub-folder. Once the options have been configured, click on the Install button to begin the installation process.
On versions of Windows with a Start menu, the newly installed Android Studio can be launched from the entry added to that menu during the installation. The executable may be pinned to the task bar for easy access by navigating to the Android Studio\bin directory, right-clicking on the executable and selecting the Pin to Taskbar menu option. Note that the executable is provided in 32-bit (studio) and 64-bit (studio64) executable versions. If you are running a 32-bit system be sure to use the studio executable.
2.3.2 Installation on macOS
Android Studio for macOS is downloaded in the form of a disk image (.dmg) file. Once the android-studio-ide-<version>-mac.dmg file has been downloaded, locate it in a Finder window and double-click on it to open it as shown in Figure 2-1:
Figure 2-1
To install the package, simply drag the Android Studio icon and drop it onto the Applications folder. The Android Studio package will then be installed into the Applications folder of the system, a process which will typically take a few minutes to complete.
To launch Android Studio, locate the executable in the Applications folder using a Finder window and double-click on it.
For future easier access to the tool, drag the Android Studio icon from the Finder window and drop it onto the dock.
2.3.3 Installation on Linux
Having downloaded the Linux Android Studio package, open a terminal window, change directory to the location where Android Studio is to be installed and execute the following command:
unzip /<path to package>/android-studio-ide-<version>-linux.zip
Note that the Android Studio bundle will be installed into a sub-directory named android-studio. Assuming, therefore, that the above command was executed in /home/demo, the software packages will be unpacked into /home/demo/android-studio.
To launch Android Studio, open a terminal window, change directory to the android-studio/bin sub-directory and execute the following command:
./studio.sh
When running on a 64-bit Linux system, it will be necessary to install some 32-bit support libraries before Android Studio will run. On Ubuntu these libraries can be installed using the following command:
sudo apt-get install libc6:i386 libncurses5:i386 libstdc++6:i386 lib32z1 libbz2-1.0:i386
On Red Hat and Fedora based 64-bit systems, use the following command:
sudo yum install zlib.i686 ncurses-libs.i686 bzip2-libs.i686
2.4 The Android Studio Setup Wizard
The first time that Android Studio is launched after being installed, a dialog will appear providing the option to import settings from a previous Android Studio version. If you have settings from a previous version and would like to import them into the latest installation, select the appropriate option and location. Alternatively, indicate that you do not need to import any previous settings and click on the OK button to proceed.
Next, the setup wizard may appear as shown in Figure 2-2 though this dialog does not appear on all platforms:
Figure 2-2
If the wizard appears, click on the Next button, choose the Standard installation option and click on Next once again.
Android Studio will proceed to download and configure the latest Android SDK and some additional components and packages. Once this process has completed, click on the Finish button in the Downloading Components dialog at which point the Welcome to Android Studio screen should then appear:
Figure 2-3
2.5 Installing Additional Android SDK Packages
The steps performed so far have installed Java, the Android Studio IDE and the current set of default Android SDK packages. Before proceeding, it is worth taking some time to verify which packages are installed and to install any missing or updated packages.
This task can be performed using the Android SDK Settingsscreen, which may be launched from within the Android Studio tool by selecting the Configure -> SDK Manager option from within the Android Studio welcome dialog. Once invoked, the Android SDK screen of the default settings dialog will appear as shown in Figure 2-4:
Figure 2-4
Immediately after installing Android Studio for the first time it is likely that only the latest released version of the Android SDK has been installed. To install older versions of the Android SDK simply select the checkboxes corresponding to the versions and click on the Apply button.
It is also possible that updates will be listed as being available for the latest SDK. To access detailed information about the packages that are available for update, enable the Show Package Details option located in the lower right-hand corner of the screen. This will display information similar to that shown in Figure 2-5:
Figure 2-5
The above figure highlights the availability of an update. To install the updates, enable the checkbox to the left of the item name and click on the Apply button.
In addition to the Android SDK packages, a number of tools are also installed for building Android applications. To view the currently installed packages and check for updates, remain within the SDK settings screen and select the SDK Tools tab as shown in Figure 2-6:
Figure 2-6
Within the Android SDK Tools screen, make sure that the following packages are listed as Installed in the Status column:
•Android SDK Build-tools
•Android Emulator
•Android SDK Platform-tools
•Android SDK Tools
•Google Play Services
•Intel x86 Emulator Accelerator (HAXM installer)
•Google USB Driver (Windows only)
In the event that any of the above packages are listed as Not Installed or requiring an update, simply select the checkboxes next to those packages and click on the Apply button to initiate the installation process.
Once the installation is complete, review the package list and make sure that the selected packages are now listed as Installed in the Status column. If any are listed as Not installed, make sure they are selected and click on the Apply button again.
2.6 Making the Android SDK Tools Command-line Accessible
Most of the time, the underlying tools of the Android SDK will be accessed from within the Android Studio environment. That being said, however, there will also be instances where it will be useful to be able to invoke those tools from a command prompt or terminal window. In order for the operating system on which you are developing to be able to find these tools, it will be necessary to add them to the system’s PATH environment variable.
Regardless of operating system, the PATH variable needs to be configured to include the following paths (where <path_to_android_sdk_installation> represents the file system location into which the Android SDK was installed):
<path_to_android_sdk_installation>/sdk/tools
<path_to_android_sdk_installation>/sdk/tools/bin
<path_to_android_sdk_installation>/sdk/platform-tools
The location of the SDK on your system can be identified by launching the SDK Manager and referring to the Android SDK Location: field located at the top of the settings panel as highlighted in Figure 2-7:
Figure 2-7
Once the location of the SDK has been identified, the steps to add this to the PATH variable are operating system dependent:
2.6.1 Windows 7
1. Right-click on Computer in the desktop start menu and select Properties from the resulting menu.
2. In the properties panel, select the Advanced System Settings link and, in the resulting dialog, click on the Environment Variables… button.
3. In the Environment Variables dialog, locate the Path variable in the System variables list, select it and click on the Edit… button. Using the New button in the edit dialog, add three new entries to the path. For example, assuming the Android SDK was installed into C:\Users\demo\AppData\Local\Android\Sdk, the following entries would need to be added:
C:\Users\demo\AppData\Local\Android\Sdk\platform-tools
C:\Users\demo\AppData\Local\Android\Sdk\tools
C:\Users\demo\AppData\Local\Android\Sdk\tools\bin
4. Click on OK in each dialog box and close the system properties control panel.
Once the above steps are complete, verify that the path is correctly set by opening a Command Prompt window (Start -> All Programs -> Accessories -> Command Prompt) and at the prompt enter:
echo %Path%
The returned path variable value should include the paths to the Android SDK platform tools folders. Verify that the platform-tools value is correct by attempting to run the adb tool as follows:
adb
The tool should output a list of command line options when executed.
Similarly, check the tools path setting by attempting to launch the AVD Manager command line tool (don’t worry if the avdmanager tool reports a problem with Java - this will be addressed later):
avdmanager
In the event that a message similar to the following message appears for one or both of the commands, it is most likely that an incorrect path was appended to the Path environment variable:
'adb' is not recognized as an internal or external command,
operable program or batch file.
2.6.2 Windows 8.1
1. On the start screen, move the mouse to the bottom right-hand corner of the screen and select Search from the resulting menu. In the search box, enter Control Panel. When the Control Panel icon appears in the results area, click on it to launch the tool on the desktop.
2. Within the Control Panel, use the Category menu to change the display to Large Icons. From the list of icons select the one labeled System.
3. Follow the steps outlined for Windows 7 starting from step 2 through to step 4.
Open the command prompt window (move the mouse to the bottom right-hand corner of the screen, select the Search option and enter cmd into the search box). Select Command Prompt from the search results.
Within the Command Prompt window, enter:
echo %Path%
The returned path variable value should include the paths to the Android SDK platform tools folders. Verify that the platform-tools value is correct by attempting to run the adb tool as follows:
adb
The tool should output a list of command line options when executed.
Similarly, check the tools path setting by attempting to run the AVD Manager command line tool (don’t worry if the avdmanager tool reports a problem with Java - this will be addressed later):
avdmanager
In the event that a message similar to the following message appears for one or both of the commands, it is most likely that an incorrect path was appended to the Path environment variable:
'adb' is not recognized as an internal or external command,
operable program or batch file.
2.6.3 Windows 10
Right-click on the Start menu, select Settings from the resulting menu and enter “Edit the system environment variables” into the Find a setting text field. In the System Properties dialog, click the Environment Variables... button. Follow the steps outlined for Windows 7 starting from step 3.
2.6.4 Linux
On Linux, this configuration can typically be achieved by adding a command to the .bashrc file in your home directory (specifics may differ depending on the particular Linux distribution in use). Assuming that the Android SDK bundle package was installed into /home/demo/Android/sdk, the export line in the .bashrc file would read as follows:
export PATH=/home/demo/Android/sdk/platform-tools:/home/demo/Android/sdk/tools:/home/demo/Android/sdk/tools/bin:/home/demo/android-studio/bin:$PATH
Note also that the above command adds the android-studio/bin directory to the PATH variable. This will enable the studio.sh script to be executed regardless of the current directory within a terminal window.
2.6.5 macOS
A number of techniques may be employed to modify the $PATH environment variable on macOS. Arguably the cleanest method is to add a new file in the /etc/paths.d directory containing the paths to be added to $PATH. Assuming an Android SDK installation location of /Users/demo/Library/Android/sdk, the path may be configured by creating a new file named android-sdk in the /etc/paths.d directory containing the following lines:
/Users/demo/Library/Android/sdk/tools
/Users/demo/Library/Android/sdk/tools/bin
/Users/demo/Library/Android/sdk/platform-tools
Note that since this is a system directory it will be necessary to use the sudo command when creating the file. For example:
sudo vi /etc/paths.d/android-sdk
2.7 Android Studio Memory Management
Android Studio is a large and complex software application that consists of many background processes. Although Android Studio has been criticized in the past for providing less than optimal performance, Google has made significant performance improvements in recent releases and continues to do so with each new version. Part of these improvements include allowing the user to configure the amount of memory used by both the Android Studio IDE and the background processes used to build and run apps. This allows the software to take advantage of systems with larger amounts of RAM.
If you are running Android Studio on a system with sufficient unused RAM to increase these values (this feature is only available on 64-bit systems with 5GB or more of RAM) and find that Android Studio performance appears to be degraded it may be worth experimenting with these memory settings. Android Studio may also notify you that performance can be increased via a dialog similar to the one shown below:
Figure 2-8
To view and modify the current memory configuration, select the File -> Settings... (Android Studio -> Preferences... on macOS) menu option and, in the resulting dialog, select the Memory Settings option listed under System Settings in the left-hand navigation panel as illustrated in Figure 2-9 below.
When changing the memory allocation, be sure not to allocate more memory than necessary or than your system can spare without slowing down other processes.
Figure 2-9
The IDE memory setting adjusts the memory allocated to Android Studio and applies regardless of the currently loaded project. When a project is built and run from within Android Studio, on the other hand, a number of background processes (referred to as daemons) perform the task of compiling and running the app. When compiling and running large and complex projects, build time may potentially be improved by adjusting the daemon heap settings. Unlike the IDE heap settings, these settings apply only to the current project.
2.8 Updating Android Studio and the SDK
From time to time new versions of Android Studio and the Android SDK are released. New versions of the SDK are installed using the Android SDK Manager. Android Studio will typically notify you when an update is ready to be installed.
To manually check for Android Studio updates, click on the Configure -> Check for Updates menu option within the Android Studio welcome screen, or use the Help -> Check for Updates... (Android Studio -> Check for Updates... on macOS) menu option accessible from within the Android Studio main window.
2.9 Summary
Prior to beginning the development of Android based applications, the first step is to set up a suitable development environment. This consists of the Android SDKs and Android Studio IDE (which also includes the OpenJDK development environment). In this chapter, we have covered the steps necessary to install these packages on Windows, macOS and Linux.
3. Creating an Example Android App in Android Studio
The preceding chapters of this book have covered the steps necessary to configure an environment suitable for the development of Android applications using the Android Studio IDE. Before moving on to slightly more advanced topics, now is a good time to validate that all of the required development packages are installed and functioning correctly. The best way to achieve this goal is to create an Android application and compile and run it. This chapter will cover the creation of a simple Android application project using Android Studio. Once the project has been created, a later chapter will explore the use of the Android emulator environment to perform a test run of the application.
3.1 About the Project
The project created in this chapter takes the form of a very simple currency conversion calculator (so simple, in fact, that it only converts from dollars to euros and does so using an estimated conversion rate). The project will also make use of one of the most basic of Android Studio project templates. This simplicity allows us to introduce some of the key aspects of Android app development without overwhelming the beginner by trying to introduce too many concepts, such as the recommended app architecture and Android architecture components, at once. When following the tutorial in this chapter, rest assured that all of the techniques and code used in this initial example project will be covered in much greater detail in later chapters.
3.2 Creating a New Android Project
The first step in the application development process is to create a new project within the Android Studio environment. Begin, therefore, by launching Android Studio so that the “Welcome to Android Studio” screen appears as illustrated in Figure 3-1:
Figure 3-1
Once this window appears, Android Studio is ready for a new project to be created. To create the new project, simply click on the Start a new Android Studio project option to display the first screen of the New Project wizard.
3.3 Creating an Activity
The first step is to define the type of initial activity that is to be created for the application. Options are available to create projects for Phone and Tablet, Wear OS, TV, Android Audio or Android Things. A range of different activity types is available when developing Android applications, many of which will be covered extensively in later chapters. For the purposes of this example, however, simply select the option to create an Empty Activity on the Phone and Tablet screen. The Empty Activity option creates a template user interface consisting of a single TextView object.
Figure 3-2
With the Empty Activity option selected, click Next to continue with the project configuration.
3.4 Defining the Project and SDK Settings
In the project configuration window (Figure 3-3), set the Name field to AndroidSample. The application name is the name by which the application will be referenced and identified within Android Studio and is also the name that would be used if the completed application were to go on sale in the Google Play store.
The Package nameis used to uniquely identify the application within the Android application ecosystem. Although this can be set to any string that uniquely identifies your app, it is traditionally based on the reversed URL of your domain name followed by the name of the application. For example, if your domain is www.mycompany.com, and the application has been named AndroidSample, then the package name might be specified as follows:
com.mycompany.androidsample
If you do not have a domain name you can enter any other string into the Company Domain field, or you may use example.com for the purposes of testing, though this will need to be changed before an application can be published:
com.example.androidsample
The Save location setting will default to a location in the folder named AndroidStudioProjects located in your home directory and may be changed by clicking on the folder icon to the right of the text field containing the current path setting.
Set the minimum SDK setting to API 26: Android 8.0 (Oreo). This is the SDK that will be used in most of the projects created in this book unless a necessary feature is only available in a more recent version.
Figure 3-3
Finally, change the Language menu to Java and click on Finish to initiate the project creation process.
3.5 Modifying the Example Application
At this point, Android Studio has created a minimal example application project and opened the main window.
Figure 3-4
The newly created project and references to associated files are listed in the Project tool windowlocated on the left-hand side of the main project window. The Project tool window has a number of modes in which information can be displayed. By default, this panel should be in Android mode. This setting is controlled by the menu at the top of the panel as highlighted in Figure 3-5. If the panel is not currently in Android mode, use the menu to switch mode:
Figure 3-5
3.6 Modifying the User Interface
The user interface design for our activity is stored in a file named activity_main.xml which, in turn, is located under app -> res -> layout in the project file hierarchy. Once located in the Project tool window, double-click on thefile to load it into the user interface Layout Editor tool which will appear in the center panel of the Android Studio main window:
Figure 3-6
In the toolbar across the top of the Layout Editor window is a menu (currently set to Pixel in the above figure) which is reflected in the visual representation of the device within the Layout Editor panel. A wide range of other device options are available for selection by clicking on this menu.
To change the orientation of the device representation between landscape and portrait simply use the drop down menu immediately to the left of the device selection menu showing the icon.
As can be seen in the device screen, the content layout already includes a label that displays a “Hello World!” message. Running down the left-hand side of the panel is a palette containing different categories of user interface components that may be used to construct a user interface, such as buttons, labels and text fields. It should be noted, however, that not all user interface components are obviously visible to the user. One such category consists of layouts. Android supports a variety of layouts that provide different levels of control over how visual user interface components are positioned and managed on the screen. Though it is difficult to tell from looking at the visual representation of the user interface, the current design has been created using a ConstraintLayout. This can be confirmed by reviewing the information in the Component Tree panel which, by default, is located in the lower left-hand corner of the Layout Editor panel and is shown in Figure 3-7:
Figure 3-7
As we can see from the component tree hierarchy, the user interface layout consists of a ConstraintLayout parent and a TextView child object.
Before proceeding, also check that the Layout Editor’s Autoconnect mode is enabled. This means that as components are added to the layout, the Layout Editor will automatically add constraints to make sure the components are correctly positioned for different screen sizes and device orientations (a topic that will be covered in much greater detail in future chapters). The Autoconnect button appears in the Layout Editor toolbar and is represented by a magnet icon. When disabled the magnet appears with a diagonal line through it (Figure 3-8). If necessary, re-enable Autoconnect mode by clicking on this button.
Figure 3-8
The next step in modifying the application is to add some additional components to the layout, the first of which will be a Button for the user to press to initiate the currency conversion.
The Palette panel consists of two columns with the left-hand column containing a list of view component categories. The right-hand column lists the components contained within the currently selected category. In Figure 3-9, for example, the Button view is currently selected within the Buttons category:
Figure 3-9
Click and drag the Button object from the Buttons list and drop it in the horizontal center of the user interface design so that it is positioned beneath the existing TextView widget:
Figure 3-10
The next step is to change the text that is currently displayed by the Button component. The panel located to the right of the design area is the Attributes panel. This panel displays the attributes assigned to the currently selected component in the layout. Within this panel, locate the text property in the Common Attributes section and change the current value from “Button” to “Convert” as shown in Figure 3-11:
Figure 3-11
The second text property with a wrench next to it allows a text property to be set which only appears within the Layout Editor tool but is not shown at runtime. This is useful for testing the way in which a visual component and the layout will behave with different settings without having to run the app repeatedly.
Just in case the Autoconnect system failed to set all of the layout connections, click on the Infer constraints button (Figure 3-12) to add any missing constraints to the layout:
Figure 3-12
At this point it is important to explain the warning button located in the top right-hand corner of the Layout Editor tool as indicated in Figure 3-13. Obviously, this is indicating potential problems with the layout. For details on any problems, click on the button:
Figure 3-13
When clicked, a panel (Figure 3-14) will appear describing the nature of the problems and offering some possible corrective measures:
Figure 3-14
Currently, the only warning listed reads as follows:
Hardcoded string "Convert", should use @string resource
