Re: Inserting In a List
On 4/2/2013 6:52 PM, Martin Gregorie wrote:
On Tue, 02 Apr 2013 18:22:55 -0400, Eric Sosman wrote:
On 4/2/2013 5:06 PM, Martin Gregorie wrote:
[...]
Its also not clear to me whether the OP is expecting some form of
sorted list of filenames. If he is expecting that, it would be best to
use a TreeMap<String> rather than an ArrayList<String> to store the
filenames.
Is there a reason to prefer TreeMap (or other SortedMap) over
accumulate-disordered-and-sort-afterward?
I think so, yes, because none of File's list() and listFiles() methods
guarantee the order of the returned files. By using TreeMap or equivalent
the OP gets the sort for free, should it be required.
"For free" seems to have swept a few coins under the rug.
The sort is by no means "free," since computational effort is
expended in producing it. My question is why one should prefer
keep-it-always-sorted-even-during-the-accumulation-phase over
just-let-the-chips-fall-and-sort-them-later. It seems to me the
latter is likely to be cheaper in both time and memory, and that
the one extra line of code ("Collections.sort(list)") is not an
overwhelming burden on the programmer.
I use it a lot, both for that and because accessing stored objects by key
from a TreeMap is almost certainly faster than scanning an ArrayMap
unless it contains very few objects indeed.
Sorry: "ArrayMap"?
--
Eric Sosman
esosman@comcast-dot-net.invalid