Re: [android-developers] Re: Can this variable become null?

Generalizing  is bad, which is why i didnt agree with the "Singletons are bad, m'kay" mentality here :)

But yeah, i agree with all your points. In some cases lazy loading makes sense, in some it doesn't.

Though i'm not sure how concurrency is an issue, Pill Pugh's implementation is probably the easiest implementation there is, not sure why some people here recommended the error-prone "instance == null" methods. 

On Sunday, March 17, 2013 9:08:34 PM UTC+2, Lew wrote:

> Lew wrote:

>> The biggest problem I have with singletons is that everyone for some god-awful reason

>> insists on lazily instantiating them. Why?

>> 

>> Lazy instantiation is lazy. What's wrong with non-lazy instantiation? Then you can use 

>> a 'final' reference to the singleton instance that exists without effort or overhead.

-- 

Lew

Piren wrote:

If your application has a singleton that takes 200MB of memory and takes a minute to load (dont ask why :-) ), but is only needed if you use a specific part of the app, why load it on the app load?

I couldn't agree more. 

But that is far more likely to be a local variable to that specific part of the app than a singleton. 

Unless, of course, you are absolutely certain to hit that "specific part of the app", 

and app-load is a time when people expect delay, and the time they hit that 

"specific part of the app" is not such a time, in which case you are far better off taking the 

performance hit at app load and not during the "specific part of the app".

Then I disagree.

However, if it truly is a singleton, or whatever, then yeah, sure, lazy load, if the 

circumstances are right, like not in that counter-scenario I just outlined, but then 

you have extra work to do it right, at least of concurrency is involved.

But that isn't a general policy of insisting on using a singleton and insisting on 

using lazy load, which is that against which I rail against.

Never generalize.

-- 

Lew

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