please add support for newArrayList(int initialCapacity) and co

[GoogleCodeExporter]

Please consider adding additional static helper methods for constructing 
ArrayLists of a known 
initial capacity. Would also be good to have the same for HashSet and HashMap. 
I absolutely love 
the static creator methods... makes for so much more concise code!

Original issue reported on code.google.com by Sam.Hall...@gmail.com on 3 Jul 2008 at 9:16

[GoogleCodeExporter]

Indeed, for the very most common collections (ArrayList, HashSet and HashMap 
only) we
do have newFooWithExpectedSize() methods.

Note that the concept of "expected size" is not exactly the same as "initial
capacity", but it's more often what you're *really* trying to express, so we 
think
it's what's most useful.

Original comment by kevin...@gmail.com on 3 Jul 2008 at 9:48

• Changed state: Invalid

[GoogleCodeExporter]

Thanks, I am clearly blind!

Must admit though... those methods are a bit of a mouthful! I suppose the 
decision was made as people would expect the 
integer parameter to be 'initial' rather than expected.

I would still request the parameters for 'initial' sizes... in many of my use 
cases, I know exactly how big the list (or hashmap) 
will be and therefore do not mean 'expected'. Your point about the difference 
is well noted, however!

Original comment by Sam.Hall...@gmail.com on 3 Jul 2008 at 10:17

[GoogleCodeExporter]

I agree they're a mouthful. I'd consider maybe removing "expected" from them and
relying on the parameter names and javadoc to convey the exact meaning behind 
"size".

Now in the case that you want to choose an initial capacity of 100 for your 
hash set,
is there really any benefit of

  Set<Thingy> thingies = Sets.newHashSetWithCapacity(100);

over

  Set<Thingy> thingies = new HashSet<Thingy>(100);

?   We think there isn't really, and you'd be better off using the latter.

It might be different if we had the ability to name the method just 
"newHashSet", but
we can't because of overload conflicts, so it has to be something else like
"newHashSetWithCapacity" which erases any possible gains.

As well, with all that said, we only feel that the static factory methods need 
to
address 95% of use cases, because having to fall back on the old-fashioned way 
for
the other 5% isn't really *that* painful.  It's when it pervades your entire 
codebase
that it's painful.

Original comment by kevin...@gmail.com on 3 Jul 2008 at 10:26

[GoogleCodeExporter]

I was hoping that you'd use the overloaded approach... if that's not possible 
then I'd consider this closed.

Good point about the overloading. I hadn't thought of it, but of course if the 
left side generic is <Integer> then 
the compiler is going to allow the integer as an entry!

Original comment by Sam.Hall...@gmail.com on 3 Jul 2008 at 10:34