What exactly is context in Android and why is it needed?

I am new to Android development and Software development too. I keep seein开发者_如何学运维g this term called - 'context' in Android code. I know that it's a class in android.content package, but I don't understand what exactly is it and why is it needed in so many places, especially in the constructors.

Can someone please explain this term to me.

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 use 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,...);

Its copy from here