Thursday, November 7, 2013

Android: Some Basic Keywords


1. Android platform:  provides API’s for mobile application development on android platform.


2. Linux kernel: android OS functionality relies on linux kernel 2.6.

3. Dalvik virtual machine: dalvik virtual machine is a register based virtual machine optimized for embedded devices.

4. .apk (Android package): All resource files and java compiled (.dex) files bundled by aapt tool into android package (.apk) file. This file used for distribution of android application.

5. .dex(dalvik executable): This is the executables file for dalvik virtual machine transformed from java compiled code by dx tool.

6. Android emulator: The Android SDK includes a mobile device emulator — a virtual mobile device that runs on your computer. The emulator lets you prototype, develop, and test Android applications without using a physical device.

7. Activities: An activity presents a visual user interface for one focused endeavor the user can undertake. A view hierarchy is placed within an activity’s window by the Activity.setContentView() method.

8. Services: A service doesn’t have a visual user interface, but rather runs in the background for an indefinite period of time.

9. Broadcast receivers: A broadcast receiver is a component that does nothing but receives and reacts to broadcast announcements.

10. Content providers: A content provider makes a specific set of the application’s data available to other applications.

11. Intents: Content providers are activated when they’re targeted by a request from a ContentResolver. The other three components — activities, services, and broadcast receivers — are activated by asynchronous messages called intents. Intent is an Intent object that holds the content of the message.

12. Context: A Context is a handle to the system. it provides services like resolving resources, obtaining access to databases and preferences, and so on. The Activity class inherits from Context. You usually have two kinds of Context, Activity and Application.

13. AndroidManifest.xml file: Before Android can start an application component, it must learn that the component exists. Therefore, applications declare their components in a manifest file that’s bundled into the Android package, the .apk file that also holds the application’s code, files, and resources. 

14. View: A View is a drawable object used as an element in your UI layout, such as a button, image, or a text label.

15. R.java file: R.java file is an index into all the resources defined in the file. You use this class in your source code as a sort of short-hand way to refer to resources you’ve included in your project.

16. Remote procedure call: Android has a lightweight mechanism for remote procedure calls (RPCs) — where a method is called locally, but executed remotely (in another process), with any result returned back to the caller.

17. Preferences: Preferences is a lightweight mechanism to store and retrieve key-value pairs of primitive data types.

18. SQLite databases: The Android API contains support for creating and using SQLite databases. Each database is private to the application that creates it.

19. Handler: A Handler allows you to send and process Message and Runnable objects associated with a thread’s MessageQueue.

20. AIDL (Android Interface Definition Language): is an IDL language used to generate code that enables two processes on an Android-powered device to talk using interprocess communication (IPC).

21. ROM: This is much similar to OS in PCs. You can transform across xp,vista,7,8,ubuntu etc.But here it's across diiferent versions of Android.

22. Stock ROM: Given by manufacturer. For e.g.,stock ROM of Xperia Tipo is Android 4.0.1 or ICS.

23. Custom ROM: ROM(OS) developed by experts (not by manufacturer) for a particular device.

24. Kernel: What kernel does in PCs, the same here.

25. Custom kernel: Associated with custom ROMs to tweak the performance of processor.

26. RAM: You know well about that in PCs. Measured in MBs(256,512,768,1024...).

27. Processor speed: Also referred as clock speed. Measured in Hz. Here, in smartphones the clock speed can be tweaked using custom kernels provided with its ROM.

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