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Samuel Fernandes
Samuel Fernandes

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Posted on    May-20-2015 12:14 AM

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In Android programming, what exactly is a Context class and what is it used for? I read about it on the developer site, but I am unable to understand it clearly.


Mayank Tripathi
Mayank Tripathi

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Posted on    May-20-2015 7:06 AM

Concept:
  • It's like access of android-activity to app's resource

  • It's similar to a when you visit a hotel, you want breakfast, lunch & dinner in suitable timings right ?

  • There are many other things you like during the time of stay. How you get these things?

  • You ask the room-service person to bring the things for you

  • Here room-service person is the context considering you are the single activity and the hotel to be your app, finally the breakfast, lunch & dinner to be the resources

As the name suggests, its the context of current state of the application/object. It lets newly created objects understand what has been going on. Typically you call it to get information regarding another part of your program (activity, package/application)

You can get the context by invoking getApplicationContext(), getContext(), getBaseContext() or this (when in the activity class).

Typical uses of context:

Creating New objects: Creating new views, adapters, listeners:
TextView tv = new TextView(getContext());
ListAdapter adapter = new SimpleCursorAdapter(getApplicationContext(), ...);
Accessing Standard Common Resources: Services like LAYOUT_INFLATER_SERVICE, SharedPreferences:
context.getSystemService(LAYOUT_INFLATER_SERVICE)   
getApplicationContext().getSharedPreferences(*name*, *mode*);
Accessing Components Implicitly: Regarding content providers, broadcasts, intent
getApplicationContext().getContentResolver().query(uri, ...);

Modified On May-20-2015 07:18:23 AM

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