Thread: modularity and interfaces:

I am studying OSGI and it seems that it always wants me to create a interface, then my code and put the whole thing in one package. In C++ this sort of thing in forced with the .h file besides the fact if you forgot to program a method it will still compile. Is it good programming practice to always create a interface? Before this I have just threw everything into one package and used inheritance.

Having interfaces for your classes can be very useful. It allows you to switch implementations half-way through your project without affecting any other parts of your application. It also gives you the flexibility of choosing an implementation best suited for the current situation. If your interfaces are only ever implemented by one lonely class, then it might seem redundant. But most of the time its hard to foresee the future and maybe at some point in time another implementation will become useful and you will thank god that you had the foresight to create an interface.

Its mostly personal preference and experience. I would advice you to use interfaces as often as possible because it encourages good coding practice and a clear documentation.

Thank you...

Do you use OSGI?

I have taken notice to Spring and it seems to have something for modularity already. I guess I am trying to wrap my head around this new concept. I understand it but all these frameworks can be overwhelming.

I have never worked with the OSGI model, but I thought your question was more about the idea behind it.

It was/is, I was just wondering if you worked with it so I could pick your brain a little more.

it is always preferable to use interface to increase the modularity of project follow lc-rp(loose coupling - runtime polymophism)

I am adopting this way of programming. What about packages? Is there a rule of thumb or good practice with modularity when creating packages? For example, take interface car, and make it its own package, then I'll have a differnt package with the implementation Class Ford, and I have several cars. Should each car be in its own package and import package with the interface, or mash them all together?

Am I on track on how this should work? Trying to develop good practices...