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From: markspace <markspace@nospam.nospam>
Newsgroups: comp.lang.java.programmer
Subject: Re: are lambdas a way to bring functional programming to java?
Date: Tue, 01 Jul 2014 14:34:02 -0700
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On 6/28/2014 5:43 AM, Wanja Gayk wrote:
 >
 > static final Comparator<String> COMPARE_BY_LENGTH
 >                = (s1,s2) -> s1.length() - s2.length()
 >
 > Collections.sort(lst, COMPARE_BY_LENGTH);

In that video you just posted featuring Brian Goetz talking about 
lambdas, Mr. Goetz says this is a bad idea.  This costs a static field 
and the time it takes to initialize the field during startup.  And you 
may never use that field, so you just spent time initializing unnecessarily.

> In article <53ae0af4$0$302$14726298@news.sunsite.dk>, Arne Vajhøj

 >> Java 8 code:
 >>
 >> Collections.sort(lst, (s1,s2) -> s1.length() - s2.length());
 >>

Whereas this code above seems to be "better" because the runtime 
compiler can hoist the lambda out of the method call and cache it, just 
like you did manually, but the compiler can do it lazily at runtime, and 
won't do it at all if it's never needed.

If you must have a named variable, I think this might be as good as the 
single line technique.

{
   ...
   final Comparator<String> byLength = (s1,s2) -> s1.length()
     - s2.length();
   Collections.sort( lst, byLength );
}

(Not compiled or tested.)

100% speculation by me, but a bit informed by just having watched Mr. 
Goetz on video.