vhandit

If you heard about the term separation of concerns , you could agree this concept is very important for making a system "clean". One of the most important characteristics of a clean system is testable. Let me tell you my story about how I've just come acrosss the design pattern Proxy. Note: to get started, you can find a very simple example of the pattern Proxy  here .  Let's start! I have an interface as below: public interface DocumentGenerator { File generate(Document document) throws BusinessException; } The following is my first implementation for a concrete class of DocumentGenerator . public class DocumentGeneratorImpl implements DocumentGenerator { private Dossier dossier; private Locale locale; public DocumentGeneratorImpl(Dossier dossier, Locale locale) { validateNotNullParams(dossier, locale); this.dossier = dossier; this.locale = locale; } private void validateNotNullParams(LibertyDossier dossier, Locale locale) { if(Objec

I n the real world, in order to use a building (hotel, supermarket, etc) we need to construct it first. This concern should be applied for software development as well. Step by step, I would like to show you the issue about no separation of constructing and using it and then I'll give you some approaches to overcome this issue. | Note : you can find the  below  demonstrated code here    Take a Look the Following Simple Application Used tools and technologies: Eclipse (Mars), JDK 1.8 I had an App which uses Controller . Controller uses Service (an interface). Finally, Service has one concrete class is DefaultService . //package vn.nvanhuong.system.separationconstructing; public class App { public static void main(String[] args) { Controller controller = new Controller(); controller.doAction(); } } public class Controller { private Service service; public void doAction(){ System.out.println("doAction in Controller"); getService().execute();