Android Glossary

The following terms are used in these documents.

.apk extension
The extension for an Android package file, which typically contains all of the files related to a single Android application. The file itself is a compressed collection of an AndroidManifest.xml file, application code (.dex files), resource files, and other files. A project is compiled into a single .apk file.
.dex extension
Android programs are compiled into .dex (Dalvik Executable) files, which are in turn zipped into a single .apk file on the device. .dex files can be created by automatically translating compiled applications written in the Java programming language.
A description of something that an Intent sender wants done. An action is a string value assigned to an Intent. Action strings can be defined by Android or by a third-party developer. For example, android.intent.action.VIEW for a Web URL, or com.example.rumbler.SHAKE_PHONE for a custom application to vibrate the phone.
A single screen in an application, with supporting Java code, derived from the Activity class.
Android Debug Bridge, a command-line debugging application shipped with the SDK. It provides tools to browse the device, copy tools on the device, and forward ports for debugging. See Listening for and broadcasting global messages.
Layout resource
An XML file that describes the layout of an Activity screen.
An XML file associated with each Application that describes the various activies, intent filters, services, and other items that it exposes. See Nine-Patch Stretchable Image for more information.
Query String
A type of URI. See the URI entry.
A user-supplied XML, bitmap, or other file, entered into an application build process, which can later be loaded from code. Android can accept resources of many types; see Resources for a full description. Application-defined resources should be stored in the res/ subfolders.
A class that runs in the background to perform various persistent actions, such as playing music or monitoring network activity.
A set of properties (text size, background color, and so on) bundled together to define various default display settings. Android provides a few standard themes, listed in (starting with "Theme_").
Android uses URI strings both for requesting data (e.g., a list of contacts) and for requesting actions (e.g., opening a Web page in a browser). Both are valid URI strings, but have different values. All requests for data must start with the string "content://". Action strings are valid URIs that can be handled appropriately by applications on the device; for example, a URI starting with "http://" will be handled by the browser.