🚀 go-pugleaf

"Ihug" <sammuel@ihug.com.au> wrote in message
news:966728868.782876@ns2.1earth.net...

> when I declare an instance of an object in Java
>
> public static void main(String []arguments)
> {
>     obj x = new obj();
> }

> now is the new operator explicitly asking for memory ?

Yes.

>..... and is x a pointer of my type obj ?....

Yes, but you are not supposed to think about it that way.

> If so then what is the difference if I have
> obj x;
>  // or
> obj y = new obj();

If you insist, obj x is a pointer, initialised to null.

What you can't do in java is declare an object "inline" in another object,
or on stack. You only ever have control of pointers to objects, not the
objects themselves.

This ** IN C **
struct x { int xx; }

void foo() {
    struct x xxx;

    xxx.xx = 3;
}

Which assigns a two (or four) byte chunk of stack to be used by a struct x,
has no equivalent in Java. In Java, you don't control memory *at all*,
except to ask for storage via the new() operator. And what you get back are
not pointers, but references - you can't do arithmetic on them, you can't
decompose them into memory adresses. A java reference is more like a windows
"handle". Maybe it helps to think of it that way. Java does not use '->' or
'*' to dereference, because a java programmer never dereferences anything -
only the underlying engine does. In effect, the C element selection oprator
'.' is not implemented in java, so java uses a dot for the job for which C
uses the arrow.

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