Android applications are simply Java applications running inside an Android virtual machine called Dalvik. You will encounter this name when compiling and running the application. The final compiled code is not fully compatible with the Oracle Java Virtual Machine, but for the purpose of this book, you are only expected to know basic Java programming.
You will need the following software and hardware:
Windows XP, Vista, 7, or 8; Linux (Ubuntu is recommended); or Mac OS 10.5.8 or a later operating system
Java SDK
Android SDK with the ADT bundle
An Android device
You should already know how to install the Java SDK (JDK) and keep it up to date. The Android SDK requires at least JDK 6. You can use higher versions if available. Always use the latest update for security and compatibility reasons.
Note
It is important to use JDK and not just the Java Runtime Environment (JRE) for development. It is also a requirement of Android SDK. Make sure the JAVA_HOME environment variable is set to the correct folder.
Android SDK contains the Eclipse Integrated Development Environment (IDE) with preinstalled plugins and Android platform tools. Using the latest version of Android SDK is recommended.
Tip
If you have used Eclipse before, you can use your own existing Eclipse installation as well, but then you are required to install the plugins manually on your own.
We are going to download and install Android SDK with the Android Development Tools (ADT) bundle in the next section. ADT allows you to install the application to your device and also connect to it in order to get important information such as the LogCat console output (text output from installed applications that is not visible to users) and other interesting statistics about running apps.
Your device should be running at least Android 2.2, but using a more recent version is recommended. If you don't own an Android device, you can use an Android emulator for development. However, consider getting a physical device because the behavior of the emulator is different from that of a real phone or tablet. The game might run slower or have problems. Emulators are known to have issues especially with hardware-accelerated graphics. Nothing can replace testing on a real device, and in fact for serious game development, it's a necessity to test on multiple devices.