Inject New Methods and Properties into Classes During Runtime

Question

Is there any way we can inject new methods and properties into classes during run-time.

http://nurkiewicz.blogspot.com/2009/09/injecting-methods-at-runtime-to-java.h

Answer 1

Is it possible by just doing using Java?

Quite so, the "only" thing you have to do is define an instrumentation agent which supplies an appropriate ClassFileTransformer, and you'll have to use reflection to invoke the added methods. Odds are this isn't what you want to do, though, but it's doable and there's a well-defined interface for it. If you want to modify existing methods you may be interested in something like AspectJ.