Android Application Fundamentals

Application Fundamentals
  • Android applications are written in the Java programming language.
  • Android applications are packaged as .apk files, it contains compiled Java code, data and resource files.
  •  .apk file is the vehicle for distributing the application and installing it on mobile devices.
  • All the code in a single .apk file is considered to be one application.
Application  Process:
  •  Every application runs in its own Linux process.
  •  Android starts the process whenever it is required to execute its components, and shuts down the process when it's no longer needed and system resources are required by other applications.
  • Each process has its own virtual machine (VM), so application code runs in isolation from the code of all other applications.
  • By default, each application is assigned a unique Linux user ID.
  • Two applications can share the same user ID and in the same Linux process, sharing the same VM.
Application Components

  •  A central feature of Android is that one application can make use of elements of other applications, subject to other application permission.
  •  Android applications don't have a single entry point for everything in the application (no main() function, for example).
  • They have essential components that the system can instantiate and run as needed. There are four types of components:    a)  Activities  b) Services c) Broadcast receivers d) Content providers
Manifest File

  • Each Android application is associated with a AndroidManifest.xml file. Its is used to define the application.
  • Specify the application name and the components of the application the activities, services, broadcast receivers, and content providers.
  • Processes hosting the application components 
  • Permissions required by the application to access protected parts of the API and interact with other applications.
  • Minimum API level required to access the application.
  • Lists of libraries that the application must be linked






























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