Should you create an interface when there is (currently) a single class that implements it?

Should you always create an interface if there's a possibility that there might be something else that could use it, or wait until there's an actual need for it then refactor to use an interface?

Programming to an interface generally seems like sound advice, but then there's YAGNI...

I guess maybe it depends on the situation. Right now I have an object representing a folder that can contain recipes or other folders. Instead of using Folder directly, should I worry about implementing something like IContainer? In case in the future I want to have a recipe that refers to other sub recipes (say an apple pie recipe that is also a container for a pie crust recipe)

It always depends on the situation. If you KNOW there is going to be another class using the interface, then yes, create the interface class to save time later. However, if you are not sure (and most of the time you aren't) then wait till you need it.

Now that doesn't mean to ignore the possibility of the interface - think about the object's public methods and such with an eye toward making an interface later, but don't clutter your codebase with anything that you don't actually NEED.

Why should I use an interface when there is only one implementation class?

I'm new at programming and I'm learning Java. I was just wondering why I should use an interface when there is only one implementation class?You do this to prevent others from accessing your implementing type. For example, you could hide your impleme

How to create a list of instances derived from a base class that implements the interface?

Consider the following interface and class declarations. public interface IMessage { string Body { get; set; } } public abstract class MessageBase : IMessage { public string Body { get; set; } } public class MessageA : MessageBase { } public class Me

When should you create an interface for the request or response for messaging in the application

I want to know if there is any need to create interface for request/response objects. I know ServletRequest is an interface. I see request/response as simple pojo, where having some members to hold data and getter/setters would suffice. The processin

Is there a relationship between the class that implements the interface and this interface?

Consider this class hierarchy: Book extends Goods Book implements Taxable As we know, there is a relationship between a subclass and its superclass (is-a). Q: Is there any relationship like "is-a" between Book and Taxable? GOOD Answers, but you

Is there an Eclipse command listing classes that implement an X interface?

A shortcut that does that will be helpful. I am both new to Eclipse and navigating a large code base, which makes going back and forth between implementations and interfaces a little bit cumbersome.You can get that by selecting the interface and hitt

Is it a good design to have an interface and an ObjectFactory class that implements it

I'm wondering about the following class design. I have one interface which is called ObjectFactory and one class that implements it which is called ObjectFactoryImpl. The class ObjectFactoryImpl has all methods for creating objects from package and t

How do you connect the & ldquo; delegate & rdquo; outputting a UITextView to a class that implements the UITextViewDelegate protocol?

How do you connect the "delegate" outlet of a UITextView to a class that implements UITextViewDelegate protocol? I can't seem to find an example in the docs The weird thing is the UITextView's "delegate" outlet has that drag 'n drop in

What should you name your controller in MVC? When should you create another one?

I have a question that really applies to any MVC framework, I'm using the Zend Framework MVC. When exactly should you create a new controller? What exactly should the Controller layer define? I've created several apps with the MVC, progressively beco

Should you create variables for an if statement?

I was wondering, what technically would be the most efficient way. What would be smarter to code with: if (args[0].toLowerCase().toString().equals("server")) { System.out.println("SERVER"); } Or: String host = args[0].toLowerCase(); if

Can you create an object when deconstructing function arguments?

Basically I'm trying to see if I can do this: var state = { lastMessage: { owner: 'lastMessageOwnerID' }, owner: 'currentMessageOwnerID' } function isSameMessageOwner ({ lastMessage, owner: currentMessage: { owner } }) { return lastMessage.owner ===

Should interfaces work in the same namespace as the concrete classes that implement them?

Is there a standard for how solutions/projects are organized in regards to interfaces and the classes that implement them? I'm working on a an MVP, DDD application and would love to hear feedback as to how others layout their projects and why they do

Creating an instance of a class that implements a generic interface

Ok I have a generic interface public IConfigurationValidator<T> { void Validate(); } a class that implements it: public class SMTPServerValidator : IConfigurationValidator<string> { public void Validate(string value) { if (string.IsNullOrEmpty

How to make this interface as type of this parameter not throw & ldquo; incompatible types & rdquo; when it is assigned to an object that implements the interface?

Without irrelevant pieces, I have: public interface A { // contents } public class B implements A { // contents } I'd like to follow the dependency interjection pattern by instantiating the object of class B in my main method then passing it into cla

In Java polymorphism, can all classes that implement an interface be created as a type interface?

As I proceed through my online tutorial, I came across this lesson. I have an interface and two classes that implements that interface. public interface Payable { double getPaymentAmount(); } and class Invoice that implements the above interface Paya

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