CODEWITHSUNDEEP
javaandroid
Zwiebel
Zwiebel

Reputation: 1615

What's meant by the "this" context?

I have looked at a lot of android tutorials over the internet. In these tutorials they use the this context for the context everywhere. I know what this keyword means in Java, but I can't make equal this, with the this keyword in Android programming. For example, at AlertDialog.Builder, on the developer.android.com site, there is only one reference at the parameters to the Context, but I can't learn what this this means here.

Upvotes: 3

Views: 10809

Answers (6)

Fender
Fender

Reputation: 3055

if you have an Activity you can use this because:

  • this is the current instance of a class
  • an Activity is inherits from the class "Context"

so you can use your current Activity as a Context.

Look here for the Acitivty doc

and here for an explanation of this

Upvotes: 12

Sunil Kumar Sahoo
Sunil Kumar Sahoo

Reputation: 53657

this is a reference to the current object

You can use this to refer to any current instance and any instance of its super class.

If your class extends Activity. It is a case of inheritance. your class is subclass and Activity class is parent class. then you can use this keyword to get instance of Activity beacause Activity class is super class of your class. This is implicit casting

also Activity class Context as superclass. so you can refer the instance of that class using this keyword.

Thanks

Upvotes: 0

Zack Marrapese
Zack Marrapese

Reputation: 12090

The keyword this is simply a reference -- within an instance of a class -- to itself.

There are two common uses of "this" in Android. These aren't particular to Android, but are valid in Java in general.

  1. this.getResources() says to call the getResources() method on this instance. The this portion of it is usually unnecessary and used implicitly.

  2. Foo.this.getResources() could be called from an inner class. This could be handy if the inner class defines getResources() also, but you want the version defined in the other class.

Upvotes: 0

Andreas Dolk
Andreas Dolk

Reputation: 114777

Here is another question where they explain Context. As activities and services extend Context, the this context is a reference to this activity or service.

Upvotes: 0

DynamicMind
DynamicMind

Reputation: 4258

Context of current class is called This in Android.

Upvotes: 0

ngesh
ngesh

Reputation: 13501

If you know "this" variable.. then u may also know that it holds reference for the current object.. so if some method asks for a Context object you can pass this variable only when it extends classes like Context or Activity.. Because Activity implements context so obeviously its a Context

Upvotes: 0

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