CODEWITHSUNDEEP
javaoopdesign-patterns
posdef
posdef

Reputation: 6532

OOP design - creation strategies/patterns

For OOP practice I am working on a hobby project, a quiz program which reads a table from txt file and asks questions about entries in the table. The idea is to have this facilitate learning of the material given for a course in our dept.

So far I wrote the I/O bit, put together a pretty modest GUI and the classes to represent the different types of entities in the datatable. I am not sure about how to proceed with the core of the program though, I mean question generation and validation.

My first idea was to have a class AbstractQuestion which pretty much defines what a question is and what fields it has (a string representation, an answer and a difficulty level). Then I thought I could write classes for different types of questions, for instance one class for simple value inquiries (like giving the name of an entity and asking for a particular property), another class for more complicated questions (for instance inquiring about interactions of entities etc).

I am not sure if this is the best way to go however. Can't really express why but I have a feeling that this is not the neatest way to go about it. Would it make sense to work on a Factory class? Essentially I need to:

I could start simple and implement only one type of question, get it to work and add new features in time but I think it's good practice to improve my understanding of OOP, and besides I'm afraid if it works and I start giving it out for people to test it out, I'll eventually end up working on something else. I'd like to be able to conceptualize my project better, and I think this could be a good opportunity to improve that.

PS: In case it wasn't obvious, I am not a programmer by educational background :)

Upvotes: 0

Views: 232

Answers (3)

Anton
Anton

Reputation: 6041

I've got simple quiz application running on production =) There are different type of questions, with different behaviours (they should be asked, answered and tipped in different fashion). Questions have different complexity etc.

In my situation, the most appropriate solution, was creation Question superclass with some abstract methods (it could be an interface as well) and different implementation. And there were QuestionGenerator (works as a factory), factory, based on some input return different implementation.

Think, about your interface (common part) of your question and use factory pattern. There could be more complicated scenario, where you can find some advantages of using AbstractFactory or Builder patter.

In my simple case, extracting interface was enought

Upvotes: 1

djna
djna

Reputation: 55897

Think in terms of two things:

  1. What objects use Question objects? What do they need Questions to do? That is we talk about the Interface(s) of the Question.
  2. How do Questions do those things? The Behaviour of the Question.

Initially, think only about the Interfaces. I'm not clear what we need the question to do. Seems to me that a question whose answer is free-form text and a question which offers a "Pick one of A to D" and a question which asks "Pick one or more of A to D" might well loom very different in a UI. So are you thinking in terms of "Question: please display yourself, get your answer and tell me the user's score" or "Question: what is your text? Question: what kind of answer do you take? Question : what are your four options? Question: the user entered 'a' what did they score?"

Once you've got the idea of the question's responsibilities clear, then you can consider the appropriate number of different Question interfaces and classes, and hence decide whether you need a creational pattern such as Factory. Factory works well when you have a number of different classes all implementing the same interface.

Factory: go make me a question. Question: go and ask the user.

Upvotes: 2

Cratylus
Cratylus

Reputation: 54074

You could use an Abstract Factory to create factories that know how to create questions based on specific parameters.
As for the notification you could use Observer Pattern. Study them and see examples in the language of your preference

Upvotes: 2

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