Question about var initialization... 2006-10-18 - By Mike New
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> Hi list, my question isn't J2EE related...
>
> I'm wondering if the vars initialization (class and instance vars) is for
> consistency (I know Java has initialization rules when var creation take
> place) or just a type-style; for example, I've analyzed code from some
> sites
> (Oracle samples, IBM, Apache, TheServerSide.com) and they initializes the
> vars in some classes and in others not...it's just a "make sure"
> question...
>
> Example 1:
> // imports ommited
> class Some {
> private List list = new ArrayList();
>
> Some() {
> }
> }
>
> Example 2:
> // imports ommited
> class Some {
> private List list;
>
> Some() {
> list = new ArrayList();
> }
> }
>
> One initializes on declaration, the other inside constructor, I don't know
> the difference; I must say I prefer the first one. Thanks in advance...
>
One difference is if you have multiple constructors, the first one will be
run for all of them. If you include the initialization in the constructor
you have a finer level of control.
The previous answer to this pointed out something I hadn't thought of. In
any case, for a new ArrayList I don't mind having it created in every
case, but in his example of a database connection (or anything remote,
potentially expensive, or complicated) I would feel more comfortable
putting it in the constructor or in an initialize method which might be in
the contstructor or might be called only when needed (lazy
initialization).
Mike
>
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