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Message:

Dynamically Typecasting or Narrowing on an object at Runtime

Posted by Michael Walters on September 18, 2000 at 12:14 PM

Suppose you have:

Base class: A
Classes derived from A: B, C, and D

You have a factory class (Factory.create(String className) ) that will return an instance of a B, C, or D if it is passed the class name.

Usually if you want to narrow on the object coming back, you'd do a typecast:
B b = (B)Factory.create("B"); , but this done only at compile time.

However, I'd like to narrow on the object at runtime instead of comile time.

Do you know how that might be done?

What I'd like is a way where I could specify in a string, the type of object I'm expecting back and still maintain the subclassed reference when it does get returned.

To recap, I could create a dynamic reference variable that
would hold the dynamically typecast'd object being returned
from the factory method.

Unless I'm mistaken, this appears to be the only thing missing in the Reflection API.

Thanks,
Mike

• dynamic typecasting alternative rabiraj June 13, 2001 at 6:07 AM (1)
  • Factory object Enrique December 12, 2001 at 8:08 PM (0)
• I agree with you... Kishori Sharan September 18, 2000 at 1:31 PM (0)