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Re: Can I put a filter into a lambda?

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On Monday, December 4, 2017 at 9:29:33 AM UTC-5, Eric Sosman wrote:
>      If you'd rather clear and repopulate the same List (as opposed
> to making a new one each time), you could use forEach():
> 
> 	rowModelIndex.clear();
> 	IntStream.range(0, modelRowCount)
>              .filter((value) -> include(value))
> 	    .forEach((value) -> rowModelIndex.add(value);
> 
> or
> 
> 	rowModelIndex.clear();
> 	IntStream.range(0, modelRowCount)
> 	    .forEach((value) ->
> 	        if (include(value)) rowModelIndex.add(value));
> 
> I don't know which of these might be faster, or whether either
> might be faster than a plain old `for' loop.  (Research project.)
> 

Thanks!  I'll check it out.

>      FWIW, Brian Goetz (who knows far more about JVM performance
> issues than I ever will) indicates that object allocation and
> collection is cheaper than commonly thought, so there's little
> if any advantage to re-using the same List object:
> 
> https://www.ibm.com/developerworks/java/library/j-jtp09275/index.html
> 
> ... which means even more research may be indicated.  (The cited
> article is twelve years old, and we may expect that JVM's have
> continued to improve meanwhile).
> 

I'd have to take another look at their code for clear() and addAll(), I would guess generating a new variable might be cheaper, but the functional difference is more important.  I'd have to check if I have something else grabbing a reference to this variable just expecting it to get updated values rather than needing to get the reference to a new variable.  I believe I did that, though offhand can't recall why.

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Thread

Can I put a filter into a lambda? Eric Douglas <e.d.programmer@gmail.com> - 2017-12-01 12:52 -0800
  Re: Can I put a filter into a lambda? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-12-01 16:28 -0500
    Re: Can I put a filter into a lambda? Eric Douglas <e.d.programmer@gmail.com> - 2017-12-04 05:03 -0800
      Re: Can I put a filter into a lambda? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-12-04 08:20 -0500
        Re: Can I put a filter into a lambda? Eric Douglas <e.d.programmer@gmail.com> - 2017-12-04 05:32 -0800
          Re: Can I put a filter into a lambda? Eric Sosman <esosman@comcast-dot-net.invalid> - 2017-12-04 09:29 -0500
            Re: Can I put a filter into a lambda? Eric Douglas <e.d.programmer@gmail.com> - 2017-12-04 07:14 -0800
            Re: Can I put a filter into a lambda? Sebastian <nowhere@nirvana.org> - 2017-12-08 15:00 +0100

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