🚀 go-pugleaf

Howard Weiner wrote:
> 
> Hi,
> 
> Hope someone can answer this....
> 
> The definition for System.in is
> 
>                public static final InputStream in = new InputStream();
> 
> But, class InputStream is abstract. In fact, it is the intended superclass
> of all derived input stream subclasses. Shouldn't the definition for
> System.in be:
> 
>                public static final FileInputStream in = new
> FileInputStream(0);
> 
> What am I missing here?
> 
> TIA.
> 
> HDW

Hello Howard, 

   Well, I went and looked arround on sun's site, and there seems to be 
no mention of the strangeness that System.in is defined to be the
abstract class InputStream.  Just from looking at the api, and reading
about System, my guess would be that System actually defines a special
imput stream that deals with whichever system it is running on, and
since you cannot instantiate System, they just left it defined to be
InputStream, so that you can reassign it to be whatever stream extending
InputStream that you want to assign it.  It's like a reference to an
input stream, if you will.  It refers to your keyboard by default, but
can be reassigned to whatever InputStream decendat yuo wish.  

hope that shines a little light in. I'll post if I find out more,
Clint Brewer