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

You can do some quite funky things with AOP, although genuine modification of classes at runtime is a pretty hairy technique that needs a lot of classloading magic and sleight of hand.

What is easier is using AOP techniques to generate a subclass of your target class and to introduce new methods into this instead, what AOP called a "mixin" or "introduction". See here to read how Spring AOP does it, although this may be quite lame compared to what you're actually trying to achieve.