Know the runtime class

["Chakravarthy, Srikanth" <Ch...@Misys.com>]

Hi,
I am creating a cross reference of classes.
If the classes have direct relations then I get all the related classes.
If there is an object of an interface that will be assigned the value of
the implementing class then I am not able to get that class as one of
the references.

For example: class B implements Interface A.
In another class C, I have an object of A. Using reflection, I have
created the object of B and assigned to object of A. 

Now, when I run my program to check the cross references for class C, I
do not get class B in the list as it is not directly involved with class
C.

Is there any way to know the instance of the object of A in the class C?
Which API method should I use for this?

Any help is deeply appreciated.

Thanks
Srikanth

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Re: Know the runtime class

[Andrew Huntwork <as...@huntwork.net>]

I'm pretty sure that you're describing the pointer aliasing problem, 
which is in general undecidable.  There are a lot of heuristic and 
approximation algorithms that compiler folks use, like Type-Based alias 
analysis, which I think comes in 2 flavors, flow sensitive and 
flow-insensitive.

basically, don't expect to discover that the concrete type of the field 
of type A in C is B.  Expect to discover that the concrete type of A is 
in a set S which happens to contain B.

hopefully, i'm misinterpreting your question and you're really asking 
about something that's solvable.  good luck :)

Chakravarthy, Srikanth wrote:
> Hi,
> I am creating a cross reference of classes.
> If the classes have direct relations then I get all the related classes.
> If there is an object of an interface that will be assigned the value of
> the implementing class then I am not able to get that class as one of
> the references.
> 
> For example: class B implements Interface A.
> In another class C, I have an object of A. Using reflection, I have
> created the object of B and assigned to object of A. 
> 
> Now, when I run my program to check the cross references for class C, I
> do not get class B in the list as it is not directly involved with class
> C.
> 
> Is there any way to know the instance of the object of A in the class C?
> Which API method should I use for this?
> 
> Any help is deeply appreciated.
> 
> Thanks
> Srikanth
> 
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> To unsubscribe, e-mail: bcel-user-unsubscribe@jakarta.apache.org
> For additional commands, e-mail: bcel-user-help@jakarta.apache.org
> 

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Re: Know the runtime class

[Dick Eimers <dw...@cs.uu.nl>]

> Is there any way to know the instance of the object of A in the class C?
> Which API method should I use for this?

Don't whether I understand you question, but java.lang.Object.getClass
takes no arguments and returns the class descriptor, i.e. an object
belonging to java.lang.Class, associated with the object on which this
method is invoked.

A side-note; Have you thought of the problems you are about to run into
considering local variables.. I mean fields can be accessed easily and
utilizing the java.lang.reflection and getClass can be used to find out
the runtime class of a value, but object references that are somewhere
on the operand stack; dynamic checks that (un)wind the stack? Problems
assure that you don't generate checks that operate on unitialized
objects..  

Have fun.. 


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