Re: [Ikvm-developers] The type of a boxed primitive

[Stephen S. <ste...@ho...>]

> When a .NET boxed int (i.e. not a java.lang.Integer) is encountered by
> Java code and it calls getClass() on the object, the Class that is
> returned is Integer.TYPE (the Class corresponding to the Java primitive
> int).

For concreteness, I'm thinking of the following Java code:

void foo(Object obj) {
  if (obj instanceof Integer) {
    Integer i = (Integer) obj;
    ...
  }
}

If this method is called with a .NET boxed int parameter, will the
instanceof method return true? In other words, is Integer.TYPE a supertype
of the java.lang.Integer class?

Stephen

----- Original Message ----- 
From: "Jeroen Frijters" <je...@su...>
To: <ikv...@li...>
Sent: Wednesday, June 09, 2004 7:50 AM
Subject: [Ikvm-developers] The type of a boxed primitive


Hello everyone,

When a .NET boxed int (i.e. not a java.lang.Integer) is encountered by
Java code and it calls getClass() on the object, the Class that is
returned is Integer.TYPE (the Class corresponding to the Java primitive
int).

This makes sense, but I didn't consciously design it like this. It's
just a natural consequence of how primitive types are handled in
reflection. I only recently discovered this issue and now I'm wondering
whether I should keep the current behaviour, or change it.

Pro current behaviour:
- It already works.
- It makes sense.

Cons:
- If Java will ever support real boxing, this approach forces Java boxes
to use .NET boxes (this would probably be desirable anyway, but not if
it is too expensive [in terms of performance]).
- Potentially confuses Java code, that never expects to see instances of
Integer.TYPE (and friends).
- It could cause complications if .NET is ever going to support strongly
typed references to boxes.

I'm leaning towards keeping the current behaviour, mostly because the
cons all seem pretty unlikely.

Any thoughts on this issue?

Regards,
Jeroen


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