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PMD suggested in my GWT project that I should change my switch to multiple ifs if it has fewer than 3 branches. I know that this is compiled to Javascript, but I wondered if it made any difference in GWT. Do you think the generated Javascript is more efficient with if's compared to switch? Does the current GWT compiler (2.4) do any optimisation on this?

jabal
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  • Do you have any performance problems here? If not, don't even think about such performance optimizing. About readability: I think `switch` is easier to read and expand - and less error prone when using `enum`s (plus you get tool support). So I would change the PMD settings, but it is a matter of taste. – Hauke Ingmar Schmidt Mar 09 '12 at 15:43
  • Unless you are a complete freak of performance and the switch is invoked millions of times, I think that you can discard without more investigation. – Guillaume Polet Mar 09 '12 at 15:44
  • I agree with you, however the PMD trend graphs are strict guys. – jabal Mar 09 '12 at 16:05
  • And that is a good thing, in general. But you don't have to agree with every assumptions they do: TooFewBranchesForASwitchStatement "Swith are designed complex branches, and allow branches to share treatement. Using a switch for only a few branches is ill advised, as switches are not as easy to understand as if. In this case, it's most likely is a good idea to use a if statement instead, at least to increase code readability." I, as stated, completely disagree, and would change that setting. – Hauke Ingmar Schmidt Mar 09 '12 at 16:27

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According to this site: http://oreilly.com/server-administration/excerpts/even-faster-websites/writing-efficient-javascript.html#the_switch_statement found via this answer: https://stackoverflow.com/a/2923007/66416 It does matter:

In JavaScript, if statements are generally faster than switch statements when there are just one or two conditions to be evaluated.

A quick scan of a compiled GWT 2.4 file found no replacements of 'small' switch statements into if statements. So it actually might be a useful suggestion of PMD.

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Hilbrand Bouwkamp
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