Re: string case clauses

From:

Lew <lewbloch@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 11 Sep 2011 20:54:22 -0700 (PDT)

Message-ID:

<48c0da0e-cdad-438b-8137-5c734b42ad3c@glegroupsg2000goo.googlegroups.com>

Arne Vajh=F8j wrote:

Roedy Green wrote:

Joshua Cranmer wrote, quoted or indirectly quoted someone who said :

1. Switch on the hashcode.
2. Verify string equalities using a linear switch for all strings that
have the same hashcode.

ouch. That amounts to a linear search comparing hashcodes. So it is
not a good idea to replace HashMap lookups with String switches.

So? How long is your switch statement? Your advice doesn't make sense.

I thought switches worked by compiled-in jumps to a case label. Was I mist=
aken? So the only linear search would be on the very rare hash collision, =
and typically no more than two deep.

Even if I'm mistaken, a linear search through a handful of cases is not goi=
ng to take significantly longer than a HashMap lookup, and will avoid the o=
verhead of creating all those objects and concomitant GC pressure. So calm=
down your panic, big boy.

Is anything different from int in pre-1.7?

Not really. If your switch is so long that a linear search is a performanc=
e problem, you have deeper problems anyway.

--
Lew