ANSWER: methods can be invoked in any order and calling method should be in same class as worker method
Methods can be invoked in any order. Methods do not need to be completed in the order in which they are listed in the class where they are declared. The way you invoke a worker class is different based on whether they are present in same class or different class there is no limit in number of method calls that a calling method can make. The calling method and worker can be in same class or different class. There are privately defined methods and so cannot be called by method in any other class.