Beginning Android Tablet Games Programming (Beginning Apress)

198 Pages·2011·3.99 MB·English

by  Jeremy Kerfs

For your convenience Apress has placed some of the front
matter material after the index. Please use the Bookmarks
and Contents at a Glance links to access them.
Contents at a Glance
 About the Author....................................................................................................ix
 About the Technical Reviewer................................................................................x
 Acknowledgments.................................................................................................xi
 Chapter 1: Setting Up Android 3.0 Java Development............................................1
 Chapter 2: Creating Simple Games with Sprites and Movement..........................27
 Chapter 3: Creating Gathering User Input.............................................................47
 Chapter 4: Adding Sound Effects, Music, and Video.............................................69
 Chapter 5: One-Player Game with Obstacles........................................................87
 Chapter 6: A Ball and Paddle Game....................................................................103
 Chapter 7: Building a Two-Player Game.............................................................121
 Chapter 8: A One-Player Strategy Game Part I...................................................137
 Chapter 9: A One-Player Strategy Game Part II..................................................151
 Chapter 10: Publishing the Game.......................................................................167
 Appendix A: Testing Android Games on a Real Device.......................................179
 Index...................................................................................................................181
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C H A P T E R 1
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Setting Up Android 3.0 Java
Development
This book teaches you to create your own games for Android 3.0 tablets. After reading and working
through its examples, you’ll have gained command over the sensors, touchscreen, network capabilities,
and processing power of the many new tablet computers. Does that sound daunting? It isn’t. Instead of
going through the drudgery of developing stodgy corporate apps that locate a store or present a coupon,
you’ll know how to make fun and intriguing games. If you’ve done some game development in the past,
you may be pleasantly surprised to learn how simple the Android system makes this process when
compared to traditional PC and console game development.
Although no book ever written can take you from newbie to game programming guru, the
foundation presented in this book will let you make any of your 2D game ideas into a reality. This book
makes the programming as simple as possible in order to concentrate on the more creative aspects of
game development.
What Is Android?
Android is very special, and you’ll gain much more appreciation for it as you get into the programming.
The movement of many handset makers to create tablets running the Android OS created a huge market
for the games you’ll make. This section gives you a rundown of Android’s features and history.
The Beginnings of Android
In 2003, Android began as a small Silicon Valley startup company with the aim to create a more
interactive and helpful interface for smartphones. Google quickly snatched up the company in 2005 as
part of its push to enter the mobile phone market. After Google acquired it, the first Android OS was
soon released during 2007. In subsequent years, Android went through many revisions (more than seven
major changes) that made it one of the leading operating systems for smartphones, with some saying
that Android has nearly 50% of mobile devices.
The revisions to Android are very important to understanding how development works. Google
worked hard to ensure backward compatibility in its version of Android; however, applications generally
are designed to work for a select couple of Android editions to guarantee the best performance and user
experience. The version called Froyo is still the most popular for developers, but the later versions are
gaining steam as more modern devices like tablets require more powerful operating systems.
The following list of Android versions, along with their current market share, illustrates which
versions remain popular and therefore are of interest to developers. The creative name given to each
version by Google is next to the edition number. Developers often go by these names rather than merely
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CHAPTER 1  SETTING UP ANDROID 3.0 JAVA DEVELOPMENT
the numbers. Keep in mind that with the exception of Android 3.0, all versions of the OS were designed
for phones exclusively:
• Android 1.5 Cupcake (2.3%)
• Android 1.6 Donut (3.0%)
• Android 2.1 Éclair (24.5%)
• Android 2.2 Froyo (65.9%)
• Android 2.3 Gingerbread (1.0%)
• Android 2.3.3 Gingerbread (3.0%)
• Android 3.0 Honeycomb (0.3%)
If you’re interested in checking the current market share of the various versions, go to
http://developer.android.com/resources/dashboard/platform-versions.html.
After examining this list, many would say that you should be making games for Froyo because it has
a huge lead in market share over other versions. The reason for Froyo’s prevalence is that it’s installed on
many simpler older phones that can only get updated versions through a complicated process. These
devices will slowly become inconsequential as the newer versions take center stage. To some extent,
making games for the majority of users makes sense; however, every day new users are buying more
modern phones that use the later versions. Also, perhaps the most important point is that hundreds of
thousands of apps are playable on the Froyo version, and it’s increasingly difficult to stand out.
With that being said, this book teaches you to designs games for the latest edition (Honeycomb) for
two reasons. First, Honeycomb is the only version optimized for tablets, which are much more
immersive and fun than any smartphone. Second, Android tablet computing is growing at a huge rate as
more companies release tablets that can compete with Apple’s iPad. With the failure of webOS, Android
and iOS are the only contenders in the tablet market. Microsoft has also come out with its own operating
system, but it has not yet garnered significant market share. Google’s often-quoted statement about
500,000 Android devices being registered each day gives you a sense of how fast this market is
expanding.
Android 3.0 Features
Honeycomb is a huge advance from the previous Android versions. Designed to utilize a much larger
screen and more powerful processor, Android 3.0 lets developers expand their usually modest
smartphone games. Many of the new features are user-interface changes that make the desktop
accessible to users with a screen that is several times bigger than a smartphone screen. For example,
typical phones have two- to three-inch screens, whereas tablets boast impressive nine- to ten-inch
screens. These updates are convenient; however, game developers concentrate more on the updates to
speedier graphics rendering and the new sensors and network abilities of the operating system.
Not all games use all of these features, but it’s crucial to consider their importance in designing
unique games. The larger screen is in itself an update worth noting. The high-resolution screens demand
artwork that is scalable and visually appealing. Many Android tablets have landed on 1280 × 800 as their
screen size. This is comparable to the resolution that many computer screens still use. In this case, the
graphics must approximate the images used in computer games.
Table 1-1 list major changes to Android 3.0 of particular interest to game developers.
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CHAPTER 1  SETTING UP ANDROID 3.0 JAVA DEVELOPMENT
Table 1-1. Android 3.0 Features
Updates to Android 3.0 Relevance to Game Development
3D user interface design Games and apps can use new themes that provide a quick and
professional look with minimal work.
Better desktop widgets Multiplayer games allow users to make simple changes right on
the desktop.
Powerful graphics capabilities Games can use more realistic high-resolution images without
losing out on fast performance.
Multicore processor support All aspects of a game can be speeded up by allocating different
routines to separate cores.
Customizable action bar Some games may find the bar at the top of the app useful for
providing updates or posting scores and points.
Notification and system bar Although this isn’t truly a game-oriented update, it can be
useful for letting users monitor any changes or updates in a
game.
Bluetooth connectivity changes Devices like joysticks and keyboards can now be readily
connected to tablets for a new user-input method.

Throughout the book, I give advice about how to make the most of the new Android tablet features.
If you’re looking to make games as a hobby by yourself, then watch for my notes about where to get
quality sounds and images royalty-free. The tools I use for making music and graphics for my games are
also explained in depth later in chapter 2.
I hope that after getting acquainted with Android, you’re ready to get started. Read the next section
carefully, though, to ensure that you have the proper skills and hardware to develop games for Android.
What You Need to Create Android Games
So what does it take to become an Android games developer? Let’s look at the skills you need to get the
most from this book and the system you need to work through its examples.
What You Need to Know
How hard is programming Android games? This really depends on how experienced you are with Java
and the Android operating system. If you have a solid knowledge of Java, then you’ll be perfectly at home
with this book. If you’ve written code for Android before, then you may not be challenged by any of the
code here and are free to enjoy the experience as you go. Read this section carefully before proceeding,
so you know exactly what you need.
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Generally, people interested in learning to create games for tablets in Android come from three
different backgrounds. Each background prepares you for the examples in this book, but they all require
a slightly different approach.
If you know both Java and Android, you’re ready to go. The code here resembles what you’ve seen
before, but it focuses on graphics, game loops, and rapid responses to user input that you may not have
dealt with. Regardless of what you’ve done, this book helps you master the creation of tablet games.
Maybe you’re comfortable with Java, but you’ve never worked with Android. This is fine. You won’t
have much difficulty working through the examples and code. Remember that with any new
environment and API, you should regularly look up the functions and classes that are presented.
Becoming familiar with Android takes time, but it’s well worth the effort.
You may never have coded so much as an if statement in Java, much less worked with Android. If
this is the case, you can still use this book, but you have to get a Java primer. I strongly recommend
Learn Java for Android Development by Jeff Friesen (Apress, 2010). When you have a reference for Java,
become familiar with how Java works, and then jump right into this text. You learn the language as you
go through it.
An understanding of XML is beneficial; however, XML is relatively simple to understand, and you
should have no problem dealing with this book’s relatively elementary use of it. With the qualifications
out of the way, it’s time to consider the environment used for game creation.
What You Need for a Platform
It's time to get your hands dirty and find out what you actually need for developing Android games.
Fortunately, you shouldn't have to buy any software! The only expense is a $25 registration fee when
you’re ready to put your games on the Android Market. First, check to make sure your computer will
support Android development:
• Windows XP (32-bit), Vista (32- or 64-bit), or Windows 7 (32- or 64-bit)
• Mac OS X 10.5.8 or later (x86 only)
• Linux (tested on Ubuntu Linux, Lucid Lynx)
This list was compiled from Android’s own system requirements. Check
http://developer.android.com/sdk/requirements.html for the most recent changes to minimum system
standards.
Although a system that meets the minimum requirements will let you create Android applications,
testing your programs may be rather slow. Generally, if you can play modern video games on your
computer, then you should be fine. However, if you have a slower machine, don’t despair; you’ll be
perfectly capable of writing Android games, but you should test them on an Android tablet rather than a
simulator on your computer.
You don’t need an Android tablet to complete any exercise or program in this book, but there is no
substitute for testing your creations on a real device. With a glut of tablets on the market, cheaper
models will set you back about $500 to $700. These are well worth the investment if you find game
programming as addicting as I do. Motorola and Samsung make some of the most popular tablets; look
for their offerings to see the top of the line in terms of Android tablets.
If you’re confident in your skills and have decided on which machine you want to plunge into game
development, you’re ready to acquire your tools and configure your development environment.
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CHAPTER 1  SETTING UP ANDROID 3.0 JAVA DEVELOPMENT
Setting Up Your Android Tablet Programming Environment
You’re nearly at the fun part, but first you must make sure your computer is properly set up. You must
download and install three packages for your work:
• Java Development Kit (JDK)
• Eclipse, which is the integrated development environment (IDE)
• Android Java SDK
If you’re a Java developer, then you likely have a recent version of the JDK and probably even have
Eclipse installed. In that case, skip to the Android SDK portion of the following instructions. Look over
the first two sections if you experience problems, though, because you may be using the wrong version
of the JDK or Eclipse.
In the following sections, you work through installing each of these packages. When you’re done,
you’ll be ready to create your first Android tablet program. This entire process shouldn’t take more than
20 minutes before you’re ready to go.
Installing the Java JDK
The first step is to download and install the latest version of the JDK for your machine. Here’s how:
1. To find the JDK you need for your system, go to
www.oracle.com/technetwork/java/javase/downloads/index.html. You need
the JDK to let you use the Java language on your computer. Look for the large
Java icon at upper left on the page, and select the JDK link, as labeled in Figure
1-1. This link takes you to the JDK SE downloads page.
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CHAPTER 1  SETTING UP ANDROID 3.0 JAVA DEVELOPMENT

Figure 1-1. Java download options page
2. On the Downloads tab of the Java SE Downloads page, shown in Figure 1-2,
accept the license agreement, choose the package that fits your operating
system, and click the link to download it.
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CHAPTER 1  SETTING UP ANDROID 3.0 JAVA DEVELOPMENT

Figure 1-2. License agreement and Java version selection
3. When the file downloads, run the installer. On some computers, the installer
starts automatically. If this doesn’t happen, locate the folder where the files
were downloaded, and sort the folder by the Date Modified. The last file is this
installer. Double-click it, and you’re ready to go.
4. When the welcome dialog page for Installation for Java wizard appears, as
shown in Figure 1-3, click the Next button and follow the instructions provided
by the wizard to finish the installation.
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