1. A method for reloading classes in an application, the method comprising: a class loader loading a class in the application, wherein the class loader is one of a hierarchal stack of class loaders each configured to load one or more classes in the application; detecting the class has been changed; replacing the class loader in the hierarchy of class loaders with a new class loader for the detected changed class; and the new class loader reloading the changed class in the application; wherein said detecting the class has been changed, said replacing the class loader and said reloading the changed class are performed while the application is executing.