hmm.. think you missed the point there peter. "two " + "three" ==
"two three" regardless of what comes before it. But I think i might
know why the optimizer picks up
"one " + "two " + "three"
but not
getOne() + "two " + "three"
it probably sees this..
(("one " + "two ") + "three")
==
(("one two ") + "three")
==
("one two three")
It can collapse one two, then the third because they are all constant.
((getOne() + "two ") + "three")
the first collapse produces something unpredictable.
On Aug 27, 7:43 am, Peter Becker <[email protected]> wrote:
> Alexey Zinger wrote:
> > There are quite a few optimizations with strings, for sure. Such as
> > replacing concatenation using "+" operator with StringBuilder and
> > concatenation of literals with a single literal (*).
>
> > There's an interesting exception to that rule. The following will
> > work as expected:
> > "one " + "two " + "three"
> > gets turned into
> > "one two three"
>
> > However, in the context of this: public String getOne() { return "one "; }
> > this: getOne() + "two " + "three"
> > will not get turned into
> > getOne() + "two three"
>
> If I am not mistaken the compiler can not replace that without
> potentially breaking the code. You method is public and non-final, which
> means it can be overwritten, so you need the dynamic dispatch, inlining
> is not ok.
>
> The JIT might do a different thing since it knows the state of the
> running system. If it should optimize that call it will need to be able
> to revert it if a baseclass of the class you describe is loaded.
>
> If the method getOne() would be either final or private, then the
> compiler should theoretically be able to inline it. No idea if it would.
>
> Peter
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