Benefit from computing String Hash at compile time?

Ulf Zibis Ulf.Zibis at
Wed Jan 6 11:05:15 PST 2010

Am 06.01.2010 10:19, Fredrik Öhrström schrieb:
> Thus the generated string switch bytecode should 
> be as easy to detect and rip out as possible. (Which was the reason for 
> my previous gripe where I wanted a simpler pattern, but I forgot about 
> the low end JVMs.) Computing the hash at runtime would make the pattern 
> worse and gain nothing since the hash is indeed specified in the 
> specification.

The computation of the hashes should only be done once on the first run
through a string switch statement, even on low end JVMs. After each
String object caches its own hash, so could be used for n more runs.
Additionally all String constants provide natively computed hashes
automatically, as they are always interned, and the equals method could
benefit from Bug Id: 6912520 
<>, not only 
for the string switch construct.


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