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public static interface ReadOnlySpliterator { | |
int characteristics(); | |
long estimateSize(); | |
long getExactSizeIfKnown(); | |
boolean hasCharacteristics(int characteristics); | |
} | |
public static <T> Collector<T, ?, List<T>> toList(ReadOnlySpliterator spliterator) { | |
Supplier<List<T>> supplier; | |
if (!spliterator.hasCharacteristics(Spliterator.CONCURRENT) && | |
spliterator.hasCharacteristics(Spliterator.SIZED)) { | |
int size = (int) spliterator.getExactSizeIfKnown(); | |
supplier = () -> new ArrayList<>(size); | |
} else { | |
supplier = ArrayList::new; | |
} | |
return Collector.of(supplier, List::add, | |
(left, right) -> { left.addAll(right); return left; }); | |
} |
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