Start Eclipse, if it’s not already running. 2.

48 Part I: The Nuts and Bolts of Android Table 2-1 Folders in the Android SDK SDK Folder Description usb_driver Contains the drivers for Android devices. If you connect your Android device to the computer, you need to install this driver so that you can view, debug, and push appli- cations to your phone via the ADT. The usb_driver folder won’t be visible until you install the USB driver. tools Contains various tools that are available for use during development — debugging tools, view-management tools, and build tools, to name a few. temp Provides a temporary swap for the SDK. At times, the SDK may need a temporary space to perform some work. This folder is where that work takes place. samples Contains a bunch of sample projects for you to play with. Full source code is included. platforms Contains the platforms that you target when you build Android applications, such as folders named android-8 which is Android 2.2, android-4 which is Android 1.6, and so on. docs Contains a local copy of the Android SDK documentation. add-ons Contains additional APIs that provide extra functionality. This folder is where the Google APIs reside; these APIs include mapping functionality. This folder remains empty until you install any of the Google Maps APIs. Targeting Android platforms Android platform is just a fancy way of saying Android version. At this writing, seven versions of Android are available, ranging from version 1.1 through version 2.2. You can target any platform that you choose. Keep in mind that several versions of Android are still widely used on phones. If you want to reach the largest number of users, I suggest targeting an earlier version. If your app requires functionality that older platforms can’t support, however, by all means target the new platform. It wouldn’t make any sense to write a Bluetooth toggle widget targeting any platform earlier than 2.0 because earlier platforms can’t use Bluetooth. Figure 2-24 shows the percentage of each platform in use as of July 1, 2010. To view the current platform statistics, visit http:developer.android. comresourcesdashboardplatform-versions.html.