Saturday, November 21, 2009

Application Fundamentals

Android applications are written in the Java programming language.
Android application archieve format is .apx
Each process has its own Java virtual machine (VM), so application code runs in isolation from the code of all other application
Android Application Components are Activites,Service,Broadcast receivers and Content providers

An application that has a visible UI is implemented with an activity. When a user selects an application from the home screen or application launcher, an activity is started.

A service should be used for any application that needs to persist for a long time, such as a network monitor or update-checking application.

Content providers
You can think of content providers as a database server. A content provider's job is to manage access to persisted data, such as a SQLite database. If your application is very simple, you might not necessarily create a content provider. If you're building a larger application, or one that makes data available to multiple activities or applications, a content provider is the means of accessing your data.

Broadcast receivers
An Android application may be launched to process a element of data or respond to an event, such as the receipt of a text message.

AndroidManifest.xml - Configuration
An Android application, along with a file called AndroidManifest.xml, is deployed to a device.
AndroidManifest.xml contains the necessary configuration information to properly install it to the device. It includes the required class names and types of events the application is able to process, and the required permissions the application needs to run.

Project Folder Structure ;
1. src - It contain the java code
2. Resource - It contain the all resource with different floder
    drawable - Icon
    raw - Sounds
    menu - Menu
    values - Project Properties
    layout - User interface Screens
3. gen - It contains the file. You could not edit manually. This have been generated automatically by understanding resource files etc.
4. AndroidManifest -It contains the Project properties
5. Android lib.

The next topic discusses the "Hello Android" Program and layout.

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