Enhancing a java object at runtime

Question

I am aware that using proxy capable libraries (javassist, JDK dynamic proxies, etc) that it is possible to enhance a class to implement an interface at runtime.

My question is: is it possible to enhance an instantiated object to implement an interface at runtime (and likewise provide appropriate method handlers).

Could you describe a use-case where doing this helps? My suggestion would be to re-consider your design if you have to do this. — Drupad Panchal
– Drupad Panchal, Commented Aug 30, 2011 at 17:46
Agreed - if, for example, you're trying to write an app that can be upgraded in-place (or something similar) without needing to be restarted, there are better ways to handle this. — jefflunt
– jefflunt, Commented Aug 30, 2011 at 17:54

Andreas Dolk · Accepted Answer · 2011-08-30 17:42:05Z

2

No, we can't change a class that has already been loaded. And we can't replace a loaded class (within a classloader).

There may be a chance if you

load a class with a custom classloader
unload the classloader (should unload the class aswell)
load the modified class again with a new classloader instance

But that is very, very black magic...

answered Aug 30, 2011 at 17:42

Andreas Dolk

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