Intercepting method calls

Question

I have this code

Foo foo = new Foo();
foo.callTheMethod();

Is there any way I can intercept the Foo.callTheMethod() call without subclassing or modifying Foo class, and without having a Foo factory?

EDIT: sorry forgot to mention this is on Android platform.

Answer 1

Use Java's Proxy class. It creates dynamic implementations of interfaces and intercepts methods, all reflectively.

Here's a tutorial.

Answer 2

Have you considered aspect-oriented-programming and perhaps AspectJ ? See here and here for AspectJ/Android info.