Introduction to Android

What is Android?

Android is an operating system based on the Linux kernel with a user interface based on direct manipulation.

•  Android is an open source software platform created by Google and the open handset Alliance.
•  It is primarily used to power mobile phones. 
•  Android consist of a complete set of software components for mobile devices including:
•  An operating system
•  A middle-ware, and
•  Embedded key mobile application
•  A large market

What is open handset alliance?

• “… Open Handset Alliance™, a group of 47 technology  an d mobile companies  have come together to accelerate  innovation in mobile and offer consumers a richer, less  ex pensive, and better mobile experience.   
• Together we have developed Android™, the first  complete open and free mobile platform complete, open, and free mobile platform.
• We are committed to commercially deploy handsets and  services using the Android Platform.

The Android Platform

• Android is a software environment built for mobile  devices. 
• It is not a hardware platform.
• Android includes:
• Linux-kernel based OS 
• A rich UI 
• Telephone functionality,  
• End‐user applications, 
• Application frameworks,

Android Components (Stack) 

• The Android stack includes a large array of features for mobile applications. 
• It would be easy to confuse Android with a  general purpose computing environment. 
• All of the major components of a computing platform are included. 

Applications Life Cycle

• An unusual and fundamental feature of android is that an application process’s life time is not directly controlled by the application itself. Instead, it is determined by the system through a combination of 

1. the parts of the application that the system knows are running, 
2. how important these things are to the user, and 
3. How much overall memory is available in the system. 

Activity Stack 

• Activities in the system are managed as an activity stack. 

•  When a new activity is started, it is placed on the top of the  stack and becomes the running activity ‐‐the previous  activity always remains below it in the stack, and will not  come to the foreground a gain until the new activity exits.

•  If the user presses the Back Button the next activity on the  stack moves up and becomes active.