Add MoreCollectors.to*WithExpectedSize helpers #173
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Curious for thoughts on these additions given some recent places these could be used |
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schlosna
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Oct 1, 2024
| * This collector has similar semantics to {@link ImmutableList#toImmutableList()}; however, | ||
| * the builder will be presized with the expected size to avoid resizing while collecting. | ||
| */ | ||
| public static <T> Collector<T, ?, ImmutableList<T>> toImmutableListWithExpectedSize(int expectedSize) { |
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probably want to steer folks toward Stream#toList() in JDK 17+
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WIP Draft for comments
Some questions came up about providing
Streamcollectors that avoid some of the growth & reallocation overhead of JDK standard collectors such asCollectors.toList()and where libraries are targeting JDK 11 so cannot useStream::toList()added in JDK 16.This typically only matters in more allocation sensitive code in which case use of Guava
Collections2.transform,Lists.transform,Maps.transformValuesmay be better solutions to avoid the intermediate collection copy; however, there are some cases where one must make a copy (e.g. if the elements being transformed are only valid inside a transaction), so providing these mechanisms may be beneficial.Questions:
filter, these likely over-allocate in what one might assume are performance/allocation sensitive paths.Streamimplementation?MoreCollectorsas that conflicts with simple type name forcom.google.common.collect.MoreCollectors?