CODEWITHSUNDEEP
javaandroidoop
Blaze Tama
Blaze Tama

Reputation: 10948

Initialize an object

Contiuned from : This is my question

So now i can use this code :

Window a = getWindow();
    a.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

Instead of this code :

getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

And some of my Senior's said that because of getWindow(); method is returning a Window Object we can use both of the code above. My question is : why we need to get a returned Window object from this code : Window a = getWindow();

I think when i do this i already have a Window Object

Window a;

But why is it not working?

And my 2nd question is why can't i do like this :

Window a = new Window();

I think it's create a Window object too.

Why must I use the getWindow(); method?

Thanks all

PS: English is not my native language, so sorry if I made some mistakes

Upvotes: 0

Views: 128

Answers (3)

OrhanC1
OrhanC1

Reputation: 1410

Think of it like this. You're doing Object oriented programming, right? You can have multiple instances of an object but they're not all the same thing.

When you use getWindow(), you're getting a specific window. When you just do 

Window a; //This will return null since the reference for some window object is created but currently points to null

or

Window a = new Window(ctx); //A window object reference is created which points to some new Window object in memory.

You're referencing a window but not the window you're intending on using.

I hope this clears things up. Please as if you have further questions.

Upvotes: 1

amit
amit

Reputation: 178521

I'm assuming java here:

Window a;

does not create a new Window object, it only creates a variable, which can hold an object of type Window. To create the object itself - you need to invoke its constructor, in your case - I assume that what getWindow() does.

Also, new Window is a syntax error - constructors in java are invoked similar to methods [with () and relevant arguments, if there are any].

Upvotes: 4

shift66
shift66

Reputation: 11958

You can create an object using it's constructor. Constructor is a method.
Window a = new Window; is syntaxical mistake in Java. And you cant use a after Window a; because in java you have to initialize a variable before using it.
Can you write with a pen just imagining about it? you have to buy that pen at first, don't you?
Window a = new Window();
this will work normally if you write it instead of Window a = new Window;

Upvotes: 2

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