What is the best way to avoid duplicating code?

[Kerr]

Hi all.

I have several times encountered this problem, but now I want to get to the bottom of it. Basically, if you have two methods that looks almost completely the same, aside from maybe one line, what is the best way to refactor it into one method? I know that you can use OOP, which is what I tend to do. Let me explain with an example of my problem.

In my current project I encountered a situation where it would just feel like overkill. I had a method that I needed to change one line in while still having the option to use the old code. But since I hate to duplicate code. So instead of creating two almost identical methods I used an interface. The method would then take a parameter with an object that implemented that interface. That object would then be used on the line to do the part I needed to change yet keep. It looks like this:

    private String getResult(Indexer i) {
        String result = data;
        int index = i.find(data); // THIS IS THE INTERESTING LINE
        if (index > -1) {
            result = data.substring(0, index);
            data = data.substring(index);
            hasMore = !data.isEmpty();
        }
        else {
            hasMore = false;
        }
        return result.trim();
    }

The line with the comment is the one I am talking about. Anyway, the thing is that this method is only used by one other method. And the interface is only used by this method. So it feels a bit overkill to use this solution, but I didnt know what the best way to solve this would be. Is this the proper way to do it? Or is there a better one?

What is the best way to avoid duplicating code in cases like this?

Take care,
Kerr

[Norm]

Could you pass index vs Indexer to the method. i appears to only be used in the one statement setting the value of index.

[Kerr]

Do´h. Now why didnt I think of that, lol?!?!

Anyway, it was more or less meant as an example. Have had this issue before. The issue with duplicate code, that is. Like when you have two or more methods that are almost exactly the same. What is the best way to deal with those situations?

[Tjstretch]

Possibly you could add a boolean parameter, if true use new code if false use old code for that line?

[Mr.777]

Try to use modular approach to avoid duplicating the code. Divide your problem into as many sub modules as you can. Modular approach gives you the reusability of the code.

[Kerr]

Yeah, its just that I have no experience with writing modular code.

[Mr.777]

Didn't you ever write functions(modules)?

[Kerr]

Are you talking about methods when you say functions? Sorry, sometimes I get stuck on words .

[Mr.777]

Are you talking about methods when you say functions? Sorry, sometimes I get stuck on words .

Yes, i mean methods!!!!!

[Kerr]

Ok . I use methods, of course. Trying to use them whenever a peace of code is used in more then one place. It is just hard to figure out how to do it (organizing the code and all, like should this method belong in this or that class, should it be static or not, how should I pass data to it, and so on) and I have never really thought of it as dividing the code into modules.