Re: Using 'final' with local variables

From:
Lew <noone@lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 15 Sep 2009 10:04:37 -0400
Message-ID:
<h8o6tn$amv$1@news.albasani.net>
Patricia Shanahan wrote:

rossum wrote:

A question for the Java gurus. When coding in C or C++ I use
'register' to hint to the compiler that something might usefully be
kept in a place with easy/quick access:

...

Have you done before/after checks to see whether it is really helping?

In some of my C code back in the early 1990's, measurements showed it
was better to let the compiler make its own choices about what to put in
registers when. I suspect C compilers have, if anything, got better
since then.

That goes even further for a Java system, because much of the
optimization is done at run time by a JVM that can see what is really
going on.


The reason to use 'final' on a local variable is, as should always be the case
for all idioms, to document and enforce a design decision. Rumor has it that
'final' makes optimization easier for Hotspot, but come on, optimizing
assignment to a local variable?

Use 'final' on a local variable to enforce that it's /definitely assigned/
exactly once, or to make it usable in an inner class.

--
Lew

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