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53 строки
1.5 KiB
Plaintext
53 строки
1.5 KiB
Plaintext
http://stackoverflow.com/questions/32859038/java-8-list-to-map-with-stream
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IntStreams:
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http://www.deadcoderising.com/2015-05-19-java-8-replace-traditional-for-loops-with-intstreams/
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Characteristics:
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SIZED
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SUBSIZED
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SORTED
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ORDERED
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DISTINCT
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NONNULL
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IMMUTABLE
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CONCURRENT
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characterized by Spliterator
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.trySplit()
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.boxed()
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???
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.sorted()
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full-barier operation (downstream ops can't start until this one ends)
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.skip() and .limit()
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does not preserve the stream size :(
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.sublis() - is more effective
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.parallell() stream really utilize Spliterator and do a HUGE perf-boost
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.distinct()
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.parallell().unordered() - can speed-up according to doc-n, but 10x slower than parallell and 3x to seq-l
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.parallell.ordered and .parallell.unordered a just 2 distinct algos
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.concat()
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??? temporary or terminal
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preserves SIZED if parts are SIZED
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.flatMap()
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like concat but better with ORDERED streams than .concat()
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disadvantages (vs concat) are:
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- no more speedup more than 2x using parallel
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- don't preserves SIZED
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- uses more memory
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- short-circuiting (find result earlier than finishing consuming all the input)
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- .flatMap...spliterator().tryAdvance() - throws OOM because of the buffering
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.orElseThrow(IllegalStateException::new)
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Java9 stuff:
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.ofNullable(System.getProperty("bla-bla"))
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.takeWhile(predicate)
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stops once a failed-to-match element found
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.dropWhile(predicate)
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-//- inverse
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.iterate(3, x -> x < 100, x -> x + 3)
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java9 adds a middle/second bound-parameter
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