Android in Action S

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Android in Action

S ^ECOND E ^DITION

W. FRANK ABLESON ROBI SEN CHRIS KING

Revised Edition of Unlocking Android

M A N N I N G

Greenwich

(74° w. long.)

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1 2 3 4 5 6 7 8 9 10 – MAL – 16 15 14 13 12 11

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v

brief contents

P ART 1 W HAT IS A NDROID ?—T HE B IG P ICTURE ...1

1

^■

Introducing Android 3

2

^■

Android’s development environment 31

P ART 2 E XERCISING THE A NDROID SDK ...61

3

^■

User interfaces 63 4

^■

Intents and Services 101 5

^■

Storing and retrieving data 129 6

^■

Networking and web services 159 7

^■

Telephony 187

8

^■

Notifications and alarms 205 9

^■

Graphics and animation 222 10

^■

Multimedia 246

11

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Location, location, location 267

P ART 3 A NDROID APPLICATIONS . ...291

12

^■

Putting Android to work in a field service application 293

13

^■

Building Android applications in C 338

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P ART 4 T HE MATURING PLATFORM ...365

14

^■

Bluetooth and sensors 367 15

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Integration 387

16

^■

Android web development 421 17

■

AppWidgets 454

18

^■

Localization 491

19

■

Android Native Development Kit 506

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vii

preface xvii

preface to the first edition xix acknowledgments xxi about this book xxiv

about the cover illustration xxix

P ÂRT 1 W ^HAT ÎS A ^NDROID ?—T ^HE B ÎG P ÎCTURE ...1

1 Introducing Android 3

1.1 The Android platform 4

1.2 Understanding the Android market 5

Mobile operators 5

^■

Android vs. the feature phones 6 Android vs. the smartphones 7

^■

Android vs. itself 8 Licensing Android 9

1.3 The layers of Android 10

Building on the Linux kernel 11

^■

Running in the Dalvik VM 12

1.4 The Intent of Android development 12

Empowering intuitive UIs 13

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Intents and how they work 13

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1.5 Four kinds of Android components 17 Activity 17

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Service 18

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BroadcastReceiver 19 ContentProvider 22

1.6 Understanding the AndroidManifest.xml file 24 1.7 Mapping applications to processes 25

1.8 Creating an Android application 26 1.9 Summary 30

2 Android’s development environment 31

2.1 Introducing the Android SDK 32

Core Android packages 33

^■

Optional packages 34 2.2 Exploring the development environment 34

The Java perspective 35

^■

The DDMS perspective 37 Command-line tools 40

2.3 Building an Android application in Eclipse 43 The Android Project Wizard 43

^■

Android sample application code 44

^■

Packaging the application 50 2.4 Using the Android emulator 51

Setting up the emulated environment 52 Testing your application in the emulator 56 2.5 Debugging your application 57 2.6 Summary 58

P ^ART 2 E ^XERCISING ^THE A ^NDROID SDK ...61

3 User interfaces 63

3.1 Creating the Activity 65

Creating an Activity class 66

^■

Exploring the Activity lifecycle 71

3.2 Working with views 74

Exploring common views 75

^■

Using a ListView 77 Multitasking with Handler and Message 81

Creating custom views 82

^■

Understanding layout 84 Handling focus 86

^■

Grasping events 87

3.3 Using resources 89

Supported resource types 89

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Referencing resources in Java 89 Defining views and layouts through XML resources 92

Externalizing values 94

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Providing animations 97

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CONTENTS

ix

3.4 Exploring the AndroidManifest file 98 3.5 Summary 99

4 Intents and Services 101

4.1 Serving up RestaurantFinder with Intent 102

Defining Intents 102

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Implicit and explicit invocation 103 Adding external links to RestaurantFinder 104

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Finding your way with Intent 106

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Taking advantage of Android-provided activities 108

4.2 Checking the weather with a custom URI 109 Offering a custom URI 109

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Inspecting a custom Uri 111 4.3 Checking the weather with broadcast receivers 113

Broadcasting Intent 113

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Creating a receiver 115 4.4 Building a background weather service 115 4.5 Communicating with the WeatherAlertService

from other apps 119

Android Interface Definition Language 119

^■

Binder and Parcelable 121

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Exposing a remote interface 122 Binding to a Service 123

^■

Starting versus binding 126 Service lifecycle 127

4.6 Summary 128

5 Storing and retrieving data 129

5.1 Using preferences 130

Working with SharedPreferences 130

^■

Preference access permissions 133

5.2 Using the filesystem 136

Creating files 136

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Accessing files 137

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Files as raw resources 138

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XML file resources 139

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External storage via an SD card 141

5.3 Persisting data to a database 144

Building and accessing a database 144

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Using the sqlite3 tool 149

5.4 Working with ContentProvider classes 149 Using an existing ContentProvider 150

^■

Creating a ContentProvider 151

5.5 Summary 158

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6 Networking and web services 159

6.1 An overview of networking 161

Networking basics 161

^■

Clients and servers 163 6.2 Checking the network status 164

6.3 Communicating with a server socket 165 6.4 Working with HTTP 168

Simple HTTP and java.net 169

^■

Robust HTTP with

HttpClient 170

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Creating an HTTP and HTTPS helper 172 6.5 Web services 178

POX—Putting it together with HTTP and XML 179

REST 181

^■

To SOAP or not to SOAP, that is the question 184 6.6 Summary 185

7 ^Telephony 7.1 Exploring telephony background and terms 188 ¹⁸⁷ Understanding GSM 189

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Understanding CDMA 189 7.2 Accessing telephony information 190

Retrieving telephony properties 191

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Obtaining phone state information 193

7.3 Interacting with the phone 195

Using intents to make calls 195

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Using phone number-related utilities 196

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Intercepting outbound calls 198

7.4 Working with messaging: SMS 199

Sending SMS messages 199

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Receiving SMS messages 202 7.5 Summary 203

8 Notifications and alarms 205

8.1 Introducing Toast 206

Creating an SMS example with a Toast 206

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Receiving an SMS message 207

8.2 Introducing notifications 210

The Notification class 210

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Notifying a user of an SMS 211 8.3 Introducing Alarms 215

Creating a simple alarm example 215

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Using notifications with Alarms 218

8.4 Summary 220

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CONTENTS

xi

9 Graphics and animation 222

9.1 Drawing graphics in Android 223

Drawing with XML 224

^■

Exploring XML drawable shapes 225

9.2 Creating animations with Android’s Graphics API 227 Android’s frame-by-frame animation 227

^■

Programmatically creating an animation 230

9.3 Introducing OpenGL for Embedded Systems 233 Creating an OpenGL context 234

^■

Drawing a rectangle with OpenGL ES 238

^■

Three-dimensional shapes and surfaces with OpenGL ES 241

9.4 Summary 245

10 ^Multimedia 10.1 Introduction to multimedia and OpenCORE 247 ²⁴⁶ 10.2 Playing audio 248

10.3 Playing video 250 10.4 Capturing media 251

Understanding the camera 252

^■

Capturing audio 257 10.5 Recording video 259

10.6 Summary 265

11 Location, location, location 267

11.1 Simulating your location within the emulator 269 Sending in your coordinates with the DDMS tool 269 The GPS Exchange Format 271

^■

The Google Earth Keyhole Markup Language 272

11.2 Using LocationManager and LocationProvider 275 Accessing location data with LocationManager 275

Using a LocationProvider 277

^■

Receiving location updates with LocationListener 279

11.3 Working with maps 281

Extending MapActivity 282

^■

Using a MapView 282 Placing data on a map with an Overlay 285

11.4 Converting places and addresses with Geocoder 288

11.5 Summary 290

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P ^ART 3 A ^NDROID APPLICATIONS . ...291

12 Putting Android to work in a field service application 293

12.1 Designing a real-world Android application 294 Core requirements of the application 295

^■

Managing the data 296

^■

Application architecture and integration 297 12.2 Mapping out the application flow 298

Mapping out the field service application 298

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List of source files 300

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Field service application’s AndroidManifest.xml 302 12.3 Application source code 302

Splash Activity 302

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Preferences used by the FieldService Activity 304

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Implementing the FieldService Activity 306 Settings 307

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Managing job data 309

12.4 Source code for managing jobs 316

RefreshJobs 317

^■

Managing jobs: The ManageJobs

Activity 320

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Working with a job with the ShowJob Activity 323 Capturing a signature with the CloseJob Activity 327

12.5 Server code 333

Dispatcher user interface 334

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Database 334

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PHP dispatcher code 335

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PHP mobile integration code 336 12.6 Summary 337

13 Building Android applications in C 338

13.1 Building Android apps without the SDK 339

The C compiler and linker tools 339

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Building a Hello World application 340

^■

Installing and running the application 342 C application build script 344

13.2 Solving the problem with dynamic linking 344 Android system libraries 345

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Building a dynamically linked application 346

^■

exit() versus return() 349

^■

Startup code 350

13.3 What time is it? The DayTime Server 352 DayTime Server application 352

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daytime.c 353 The SQLite database 355

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Building and running the DayTime Server 358

13.4 Daytime Client 360

Activity 360

^■

Socket Client 361

^■

Testing the Daytime Client 362

13.5 Summary 362

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CONTENTS

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P ^ART 4 T ^HE ^MATURING ^PLATFORM . ...365

14 Bluetooth and sensors 367

14.1 Exploring Android’s Bluetooth capabilities 368 Replacing cables 369

^■

Primary and secondary roles and sockets 369

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Trusting a device 370

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Connecting to a remote device 372

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Capturing Bluetooth events 374

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Bluetooth permissions 375

14.2 Interacting with the SensorManager 375 Types of sensors 376

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Reading sensor values 377 Enabling and disabling sensors 378

14.3 Building the SenseBot application 379

User interface 380

^■

Interpreting sensor values 382 Driving the robot 383

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Communication with the robot 384 14.4 Summary 385

15 Integration 387

15.1 Understanding the Android contact model 388 Choosing open-ended records 388

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Dealing with multiple accounts 390

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Unifying a local view from diverse remote stores 392

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Sharing the playground 393

15.2 Getting started with LinkedIn 393 15.3 Managing contacts 395

Leveraging the built-in contacts app 395

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Requesting operations from your app 398

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Directly reading and modifying the contacts database 399

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Adding contacts 400

15.4 Keeping it together 403

The dream of sync 403

^■

Defining accounts 404 Telling secrets: The AccountManager service 405 15.5 Creating a LinkedIn account 406

Not friendly to mobile 406

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Authenticating to LinkedIn 407 15.6 Synchronizing to the backend with SyncAdapter 414

The synchronizing lifecycle 414

^■

Synchronizing LinkedIn data 414

15.7 Wrapping up: LinkedIn in action 417

Finalizing the LinkedIn project 417

^■

Troubleshooting tips 418 Moving on 419

15.8 Summary 419

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16 Android web development 421

16.1 What’s Android web development? 422

Introducing WebKit 422

^■

Examining the architectural options 423

16.2 Optimizing web applications for Android 424 Designing with mobile in mind 424

^■

Adding the viewport tag 426

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Selectively loading content 428

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Interrogating the user agent 428

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The media query 429

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Considering a made- for-mobile application 430

16.3 Storing data directly in the browser 431

Setting things up 432

^■

Examining the code 433

^■

The user interface 433

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Opening the database 435

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Unpacking the transaction function 436

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Inserting and deleting rows 438 Testing the application with WebKit tools 439

16.4 Building a hybrid application 440

Examining the browser control 440

^■

Wiring up the control 441 Implementing the JavaScript handler 443

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Accessing the code from JavaScript 445

^■

Digging into the JavaScript 445 Security matters 447

^■

Implementing a WebViewClient 448 Augmenting the browser 448

^■

Detecting navigation events 449 Implementing the WebChromeClient 452

16.5 Summary 453

17 ^AppWidgets 17.1 Introducing the AppWidget 455 ⁴⁵⁴

What’s an AppWidget? 455

^■

AppWidget deployment strategies 457

17.2 Introducing SiteMonitor 458

Benefits of SiteMonitor 458

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The user experience 459 17.3 SiteMonitor application architecture 462

Bird’s-eye view of the application 462

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File by file 464 17.4 AppWidget data handling 465

17.5 Implementing the AppWidgetProvider 469

AppWidgetProvider method inventory 469

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Implementing SiteMonitorWidgetImpl 470

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Handling zombie widgets 472 17.6 Displaying an AppWidget with RemoteViews 473

Working with RemoteViews 473

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UpdateOneWidget

explained 474

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CONTENTS

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17.7 Configuring an instance of the AppWidget 476 AppWidget metadata 477

^■

Working with Intent data 478 Confirming widget creation 479

17.8 Updating the AppWidget 480

Comparing services to alarms 481

^■

Triggering the update 482 Updating the widgets, finally! 484

17.9 Tying it all together with AndroidManifest.xml 488 17.10 Summary 489

18 Localization 491

18.1 The need for localization 492 18.2 Exploring locales 493

18.3 Strategies for localizing an application 494 Identifying target locales and data 494

^■

Identifying and managing strings 495

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Drawables and layouts 497 Dates, times, numbers, and currencies 498

^■

Working with the translation team 499

18.4 Leveraging Android resource capabilities 500 More than locale 500

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Assigning strings in resources 500 18.5 Localizing in Java code 502

18.6 Formatting localized strings 503 18.7 Obstacles to localization 504 18.8 Summary 505

19 Android Native Development Kit 506

19.1 Introducing the NDK 507

Uses for the NDK 507

^■

Looking at the NDK 508 19.2 Building an application with the NDK 509

Demonstrating the completed application 510 Examining the project structure 511

19.3 Building the JNI library 512

Understanding JNI 512

^■

Implementing the library 513 Compiling the JNI library 518

19.4 Building the user interface 519

User interface layout 519

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Taking a photo 521

Finding the edges 523

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19.5 Integrating the NDK into Eclipse 524 19.6 Summary 526

appendix A Installing the Android SDK 527 appendix B Publishing applications 538

index 551

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xvii

preface

When we set out to write the first version of this book, many friends and family won- dered just what this Android thing was all about. Now, two years after the publication of the first edition, Android is nearly a household term.

The first edition of the book, Unlocking Android, enjoyed enough success that we were privileged to have the opportunity to write this second edition, renamed as Android in Action. The first thirteen chapters of the book have been refreshed and/or rewritten to bring the content up to date with Android 2.2+. Six chapters were added, bringing in more topics of interest that stray from the simplistic but are still within the realm of instructional and informational. The new content extends beyond the basics of Android development, including some topics that I’ve envisioned for a long time but lacked the proper platform to bring them to fruition. We could have written many more chapters, but we had to draw the line somewhere!

The second edition of this book was written by Frank Ableson, Robi Sen, and Chris King. Chris updated chapters 4, 5, 7, and 11. Some excellent content originally writ- ten by Charlie Collins remains in this second edition. Early on in the project Chris and I were discussing the need to bring social networking into the book. Chris exam- ined the available social networks and came back with a clever mechanism to integrate the Android contacts database with the popular business networking service LinkedIn. His work is shown in chapter 15, “Integration.” The application from chap- ter 15 is available as a free download in the Android Market.

Robi updated his chapters on notifications, graphics, and media, while I focused

on some new content areas of interest, including Bluetooth communications, sen-

sors, localization, AppWidgets, native development in C, and web development for

Android.

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In addition to the LinkedIn application from chapter 15, two more applications from this book are available in the Market as free downloads. The first is SenseBot—

an application that allows you to drive a

LEGO

Mindstorms-powered robot by tilting your phone. The application demonstrates both the sensor subsystem of Android, as well as communicating with Bluetooth. The other application available in the Market is called FindEdges. FindEdges demonstrates the Android Native Development Kit as it exercises an image processing algorithm written in the C language.

All in all, writing a book for Android is both exciting and challenging. Android continues to mature and promises to be a major player for years to come. Many thanks are owed to readers of the first edition, for without you, there wouldn’t be a second edition!

F

RANK

A

BLESON

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xix

preface to the first edition

The first mobile applications I had the opportunity to work with were inventory con- trol programs used in retail and manufacturing settings. The “terminals,” as we called them at the time, were heavy and expensive. They had big antennas, lots of clunky keys, grayscale

LCD

displays, and they looked like they came straight from the set of a science fiction movie.

From that austere beginning, my mobile horizons expanded when the Palm Pilot became the craze in the mid to late 1990s. My first significant Palm

OS

project was to develop an

IrDA

communications library for an application that printed calendars, contacts, and task-lists. Back then, the hip printers had an

IrDA

port and it was cool to beam your business card to someone. Ironically, I always enjoyed designing and writ- ing the software more than using the devices themselves.

Fast forward ten years, and I have had the privilege of working on some very chal- lenging and engaging mobile software projects for numerous clients along the way.

Much of my career to date can be traced back to relationships stemming from my early mobile development experiences—and what a blessing it has been for me. I just love the question, “would it be possible to…?” And more often than not, the answer has been “Yes!” What I particularly enjoy is helping change the way a business operates or the way problems are solved through the application of mobile software. Mobile technology can and will continue to change the way we live, work, and play…and this brings me to Android and this book.

In the fall of 2007, I was speaking with my friend Troy Mott, who happens to be an

editor for Manning, the publisher of this book. Troy and I were discussing the mobile

marketplace, something we’ve been doing for years. We started kicking around the

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idea of writing a book on Android. The challenge was that Android didn’t really exist.

Yet. We knew from some of the preliminary information that the platform promised to be open, capable, and popular. We felt that those ingredients could make for an inter- esting and valuable topic, so we began thinking about what that book might look like, taking it on faith that the platform would actually come to fruition.

Before long, we convinced ourselves (and Manning) that this was a good idea and the work began in early 2008. Beyond the usual challenges of putting a book together, we had the additional obstacle that our subject matter has been in a steady, though unpredictable, state of change over the past year. In essence, we’ve written this book twice because the

SDK

has been changed multiple times and Android-equipped phones have become available, accelerating the interest and demand for the plat- form. Every time a significant change occurred, we went back and revisited portions of the book, sometimes rewriting entire chapters to accommodate the latest develop- ments in the Android platform.

I say “we” because in the process of writing this book, Troy and I decided to share the fun and brought in two experienced authors to contribute their expertise and enthusiasm for this platform. It has been a pleasure getting to know and working with both Charlie Collins and Robi Sen. While I focused on the first and third parts of the book in the first edition, Charlie and Robi wrote part 2, which covers the important fundamentals of writing Android applications. Thanks to their contributions, I enjoyed the freedom to express my vision of what Android means to the mobile space in the first part of the book, and then to work on a couple of more advanced applica- tions at the end of the book.

We hope that you enjoy reading this book and that it proves to be a valuable resource for years to come as together we contribute to the future of the Android platform.

F

RANK

A

BLESON

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xxi

acknowledgments

Perhaps the only thing more challenging than writing a technical book is writing the second edition. There is a lot of excitement when writing the proposed table of con- tents for the updated edition but at some point the work must commence. The size and scope of this project meant working together as a team from the start. I had the privi- lege of working again with Robi Sen from the first edition and also with experienced developer and writer Chris King. Along with the help of the talented team at Manning, we are pleased to present Android in Action, the update to Unlocking Android.

In particular, we’d like to acknowledge and thank those at Manning who helped bring this book about. First, thanks to Troy Mott, our acquisition and development editor, who has been involved in every aspect of both the first and second editions.

Troy was there from the beginning, from the “what if” stages, through helping push us over the goal line—twice! Karen Tegtmeyer did all the big and little things to bring the project together; Mary Piergies skillfully piloted the team through the harrowing production process; and Marjan Bace, our publisher, showed an attention to detail at once challenging, beneficial, and appreciated.

Once the writing was done, the next round of work began and special thanks need

to go to: Benjamin Berg who performed the pre-production editing pass, Joan Celmer

and Liz Welch, our copyeditors, who made our content readable in cases where it

went either “too geek” or where the geek in us tried to be “too literary;” Elizabeth

Martin, our proofreader, who added common sense to the project, as well as a terrific

sense of humor and encouraging attitude; Janet Vail who jumped in at the last minute

to help us bring the final pieces of the project together; and finally Dottie Marsico

who handles the actual layout of the pages. It is sometimes hard to envision the final

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product when looking at edits upon edits in

MS

Word, but Dottie’s magic makes the product you hold in your hands. Thanks to each of you for your special contribution to this project. Next, we would like to thank Candace Gillhooley for her efforts in get- ting the word out about the book.

And special thanks to the other reviewers who read our revised manuscript at dif- ferent times during its development: Michael Martin, Orhan Alkan, Eric Raymond, Jason Jung, Frank Wang, Robert O’Connor, Paul Grebenc, Sean Owen, Loïc Simon, Greg Donald, Nikolaos Kaintantzis, Matthew Johnson, and Patrick Steger; and to Michael Galpin and Jérôme Bâton for their careful tech review of the final manuscript during production.

Lastly, we want to thank the thoughtful and encouraging

MEAP

subscribers who provided feedback along the way; the book is better thanks to your contributions.

Frank Ableson

I would like to thank Robi Sen, Chris King, and Troy Mott for their contributions, col- laboration, and endurance on this project! And of course, my wife Nikki and my chil- dren deserve special recognition for the seemingly endless hours of wondering when I would emerge from the “lab” and what mood I would be in—either elation when the robot worked, or near depression when the AppWidgets wouldn’t go away. Thank you for getting neither too excited nor too concerned! My staff at navitend also deserve a big thank you for carrying the water while I finished my work on this project. Finally, a big thank you to Miriam Raffay from Madridiam.com, who provided the much- needed Spanish translations for chapter 18. Gracias!

Chris King

I am deeply grateful to Troy Mott and Frank Ableson for bringing me into this project and providing support and inspiration throughout. Troy has been welcoming and enthusiastic, showing great flexibility as we discussed what projects to undertake.

Frank has a keen eye for quality, and provided great guidance from start to finish on how to craft the best book possible. I also appreciate all the work done by the review- ers and editors from Manning, whose contributions have improved the text’s accuracy and style. Working on this book has been a joy, and I’ve greatly enjoyed the opportuni- ties to contribute more and more to its progress.

Thanks also to the crew at Gravity Mobile, especially Noah Hurwitz, Chris Lyon,

Young Yoon, and Sam Trychin. You guys keep my life fun and challenging, and have

made mobile development an even better place to work. Finally, my love to my fam-

ily: Charles, Karen, Patrick, Kathryn, and Andrew. You’ve made everything possible

for me.

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ACKNOWLEDGMENTS

xxiii

Robi Sen

I would like to thank Troy Mott and the team—and everyone at Manning Publica-

tions— for their hard work making this book something worth reading. I would like to

thank my coauthors, Frank and Chris, who were great to work with and very under-

standing when I was the one holding things up. I would also like to thank Jesse Dailey

for his help with Open

GL

as well as David Cartier with the Contacts

API

. Finally, I

would like to thank my family who, more often than I liked, had to do without me

while I worked on my chapters, worked multiple jobs, and finished grad school.

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xxiv

about this book