Cannot change Java Method even after class changed

I am using a java library and I have changed a method (changed name similar code) the library compiles correctly. I have a place where I used to call the old method name and I have changed it to the new method name, but the method did not exist. So I got a collection of all methods for the class and the old method is still displayed as available and the new one was not. I have changed the class name and the new class name is loaded, but the old methods are still available and so is the new method. Now some code that I did not change is givng me a Parameter mismatch even though the signatures are the same [“addContact”, “([Ljava/lang/String;)V”, 1]

What is the deal? IS there any good reference for this LS2J stuff?