ActivityCreator
activityCreator (.bat or .pn) is a simple command-line tool that is used to set up a basic development environment. When run from the command line, activityCreator will set up the shell files needed to create a basic Android application. Having these shell files is especially useful if you are not using Eclipse. The Android plugin for Eclipse sets up these shell files for you by calling the activityCreator when you create a new project.
Depending on what type of environment you are running, you will see the activityCreator represented by a different type of script file. If you are in a Windows environment, this will be a .bat file; otherwise it will be a python (.pn) script. You simply execute the script, which in turn calls the actual activityCreator process with the correct parameters.
APIs
The API, or application programming interface, is the core of the Android SDK. An API is a collection of functions, methods, properties, classes, and libraries that is used by application developers to create programs that work on specific platforms. The Android API contains all the specific information that you need to create applications that can work on and interact with an Android-based application. The Android SDK also contains two supplementary sets of APIs—the Google APIs and the Optional APIs. Subsequent chapters will focus much more on these APIs as you begin writing applications that utilize them. For now, take a quick look at what they include so that you are familiar with their uses.
Google APIs
The Google APIs are included in the Android SDK and contain the programming references that allow you to tie your applications into existing Google services. If you are writing an Android application and want to allow your user to access Google services through your application, you need to include the Google API. Located in the android.jar file, the Google API is contained within the com.google.* package. There are quite a few packages that are included with the Google API. Some of the packages that are shipped in the Google API include those for graphics, portability, contacts, and calendar utilities. However, the packages devoted to Google Maps will be the primary focus of us.
Using the com.google.android.maps package, which contains information for Google Maps, you can create applications that interact seamlessly with the already familiar interface of Google Maps. This one set of packages opens a whole world of useful applications just waiting to be created.
The Google API also contains a useful set of packages that allows you to take advantage of the newer Extensible Messaging and Presence Protocol (XMPP) developed by the Jabber open source community. Using XMPP, applications can quickly become aware of other clients’ presence and availability for the purpose of messaging and communications. The API packages dealing with XMPP are very useful if you want to create a “chat”-style program that utilizes the phone messaging capabilities.
Optional APIs
The Android SDK includes a number of Optional APIs that cover functionality not covered by the standard Android APIs. These Optional APIs are considered optional because they deal with functionality that may or may not be present on a given handset device. That is, some devices created for the Android platform may include upgrades and features that others do not; the Optional APIs cover your programming options when trying to utilize these features in your Android applications.
One of these optional features is a cell-phone-based GPS. The Android LBS (Location-Based Services) API deals with the functionality needed to receive and utilize information from a device’s GPS unit. (Combine the information in the Android LBS API with that in the Google Maps API, and you might have a very useful application that can automatically display a map of where you are located at any given point in time.) Other Optional APIs include those for utilizing Bluetooth, Wi-Fi, playing MP3s, and accessing 3-D—OpenGL-enable hardware.
