Brigadier Brigadier - 5 months ago 15
Android Question

What is 'Context' on Android?

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.

Answer

Putting it simply:

As the name suggests, it's 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 and 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, ...);
    
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