Collection of strings - two different ways

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Peppy - 24 May 2007 11:32 GMT

Hi,

I was looking at creating a collection of strings and I've seen two
different means of doing this

List <String> list = new ArrayList <String> ( );
ArrayList <String> list = new ArrayList <String> ( );

which one should I use?

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Hendrik Maryns - 24 May 2007 11:43 GMT

Peppy schreef:

> Hi,
>
[quoted text clipped - 5 lines]
>
> which one should I use?

The first. Google for ‘prefer interface over implementation’ or some
rule in that line.

H.
- --
Hendrik Maryns
http://tcl.sfs.uni-tuebingen.de/~hendrik/
==================
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Robert Klemme - 24 May 2007 12:14 GMT

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> The first. Google for ‘prefer interface over implementation’ or some
> rule in that line.

Exception: you need some methods specific to the class (for example
LinkedLists's removeFirst()).

robert

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Lew - 24 May 2007 13:16 GMT

Peppy schreef:

>>> List <String> list = new ArrayList <String> ( );
>>> ArrayList <String> list = new ArrayList <String> ( );

>> The first. Google for ‘prefer interface over implementation’ or some
>> rule in that line.

"Use the most general type appropriate to your algorithm."

If List is too general, use the second, otherwise prefer the first as Robert said.

One advantage of the first is that you can very easily refactor the
declaration, e.g.,
List <String> stuff = new TreeList <String> ();

Side note: "list" is a terrible name for a variable, especially if its type is
not "List", as in the second case. Either way it says little to nothing about
the interpretation of the variable.

Signature

Lew

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Hendrik Maryns - 24 May 2007 17:23 GMT

Robert Klemme schreef:

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[quoted text clipped - 15 lines]
> Exception: you need some methods specific to the class (for example
> LinkedLists's removeFirst()).

Well, no, then you probably want to declare the variable of the type
Deque. LinkedList implements a lot of interfaces. I have used it as a
Queue as well.

H.
- --
Hendrik Maryns
http://tcl.sfs.uni-tuebingen.de/~hendrik/
==================
http://aouw.org
Ask smart questions, get good answers:
http://www.catb.org/~esr/faqs/smart-questions.html

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Collection of strings - two different ways

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