Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.java.programmer > #38524
| From | Eric Sosman <esosman@comcast-dot-net.invalid> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: Is there a better way to group and sort objects? |
| Date | 2018-08-07 14:36 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <pkcoql$q0m$1@dont-email.me> (permalink) |
| References | <8c045ff4-98c5-4253-9136-b26b34cf8f77@googlegroups.com> <pkc7nj$6du$1@dont-email.me> <fbdc6564-aa69-4db8-9e90-393ea9469f05@googlegroups.com> <pkcnmi$ioq$1@dont-email.me> |
On 8/7/2018 2:16 PM, Eric Sosman wrote:
> [...]
> Using the value returned by put() saves one map lookup in the case
> when the key is already present. (When I wrote "in half" I was being
> over-optimistic about the likelihood of duplicates.)
No, I was right, after all. What you wrote:
Value newValue = ...;
String key = ...;
if (map.containsKey(key)) {
Value oldValue = map.get(key);
... merge oldValue and newValue ...
} else {
map.put(key, newValue);
}
... always searches the map twice. My suggestion:
Value newValue = ...;
String key = ...;
Value oldValue = map.put(key, newValue);
if (oldValue != null) {
... merge oldValue and newValue ...
}
... searches it once, whether the key is present or absent. One
search instead of two is "in half."
--
esosman@comcast-dot-net.invalid
Eight hundred ninety-seven days to go.
Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-07 06:00 -0700
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-07 09:44 -0400
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-07 11:33 -0400
Re: Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-07 10:22 -0700
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-07 14:16 -0400
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-07 14:36 -0400
Re: Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-07 12:13 -0700
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-07 16:00 -0400
Re: Is there a better way to group and sort objects? Martin Gregorie <martin@mydomain.invalid> - 2018-08-08 08:20 +0000
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-08 06:57 -0400
Re: Is there a better way to group and sort objects? Martin Gregorie <martin@mydomain.invalid> - 2018-08-08 11:08 +0000
Re: Is there a better way to group and sort objects? Martin Gregorie <martin@mydomain.invalid> - 2018-08-08 11:22 +0000
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-08 07:45 -0400
Re: Is there a better way to group and sort objects? Martin Gregorie <martin@mydomain.invalid> - 2018-08-08 14:12 +0000
Re: Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-08 05:50 -0700
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-08 09:23 -0400
Re: Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-08 06:47 -0700
Re: Is there a better way to group and sort objects? Eric Sosman <esosman@comcast-dot-net.invalid> - 2018-08-08 10:31 -0400
Re: Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-08 08:24 -0700
Re: Is there a better way to group and sort objects? Robert Klemme <shortcutter@googlemail.com> - 2018-08-14 14:06 +0200
Re: Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-14 05:49 -0700
Re: Is there a better way to group and sort objects? Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2018-08-09 16:06 +0200
Re: Is there a better way to group and sort objects? Eric Douglas <e.d.programmer@gmail.com> - 2018-08-14 05:47 -0700
csiph-web