Stream.toList()和Collectors.toList()的性能比较 |
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Stream.toList()和Collectors.toList()的性能比较
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昨天给大家介绍了Java 16中的Stream增强，可以直接通过toList()来转换成List。 主要涉及下面这几种转换方式： list.stream().toList(); list.stream().collect(Collectors.toList()); list.stream().collect(Collectors.toUnmodifiableList());然后，看到有网友评论问：Stream.toList()和Collectors.toList()的区别是什么？哪个性能好？ 处理结果的区别，其实上一篇文章和视频里都有说： Stream.toList()返回的List是不可变List，不能增删改 Collectors.toList()返回的是个普通的List，可以增删改 Collectors.toUnmodifiableList()返回的List是不可变List，不能增删改而至于性能的话，今天我们就来测试一下，看看哪个性能更好。 @BenchmarkMode(Mode.All) @Fork(1) @State(Scope.Thread) @Warmup(iterations = 20, time = 1, batchSize = 10000) @Measurement(iterations = 20, time = 1, batchSize = 10000) public class BenchmarkStreamToList { @Benchmark public List streamToList() { return IntStream.range(1, 1000).boxed().toList(); } @Benchmark public List collectorsToList() { return IntStream.range(1, 1000).boxed().collect(Collectors.toList()); } @Benchmark public List streamToList() { return IntStream.range(1, 1000).boxed().toList(); } }结果报告： Benchmark Mode Cnt Score Error Units BenchmarkStreamToList.collectorsToList thrpt 20 24.422 ± 0.268 ops/s BenchmarkStreamToList.collectorsToUnmodifiableList thrpt 20 22.784 ± 0.599 ops/s BenchmarkStreamToList.streamToList thrpt 20 31.779 ± 1.732 ops/s BenchmarkStreamToList.collectorsToList avgt 20 0.045 ± 0.006 s/op BenchmarkStreamToList.collectorsToUnmodifiableList avgt 20 0.062 ± 0.035 s/op BenchmarkStreamToList.streamToList avgt 20 0.040 ± 0.028 s/op BenchmarkStreamToList.collectorsToList sample 445 0.046 ± 0.002 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.00 sample 0.039 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.50 sample 0.041 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.90 sample 0.057 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.95 sample 0.073 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.99 sample 0.102 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.999 sample 0.150 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.9999 sample 0.150 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p1.00 sample 0.150 s/op BenchmarkStreamToList.collectorsToUnmodifiableList sample 460 0.044 ± 0.001 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.00 sample 0.042 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.50 sample 0.044 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.90 sample 0.046 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.95 sample 0.047 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.99 sample 0.051 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.999 sample 0.057 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.9999 sample 0.057 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p1.00 sample 0.057 s/op BenchmarkStreamToList.streamToList sample 655 0.031 ± 0.001 s/op BenchmarkStreamToList.streamToList:streamToList·p0.00 sample 0.030 s/op BenchmarkStreamToList.streamToList:streamToList·p0.50 sample 0.031 s/op BenchmarkStreamToList.streamToList:streamToList·p0.90 sample 0.032 s/op BenchmarkStreamToList.streamToList:streamToList·p0.95 sample 0.033 s/op BenchmarkStreamToList.streamToList:streamToList·p0.99 sample 0.035 s/op BenchmarkStreamToList.streamToList:streamToList·p0.999 sample 0.037 s/op BenchmarkStreamToList.streamToList:streamToList·p0.9999 sample 0.037 s/op BenchmarkStreamToList.streamToList:streamToList·p1.00 sample 0.037 s/op BenchmarkStreamToList.collectorsToList ss 20 0.043 ± 0.001 s/op BenchmarkStreamToList.collectorsToUnmodifiableList ss 20 0.045 ± 0.004 s/op BenchmarkStreamToList.streamToList ss 20 0.031 ± 0.001 s/op从报告中我们可以看到： 吞吐量：streamToList > collectorsToList > collectorsToUnmodifiableList 平均耗时：streamToList > collectorsToList > collectorsToUnmodifiableList p0.9999耗时：streamToList > collectorsToUnmodifiableList > collectorsToList 冷启动耗时：streamToList > collectorsToList > collectorsToUnmodifiableList所以，Stream.toList()的性能要各方面都要好于Collectors.toList()和Collectors.toUnmodifiableList()。 如果您学习过程中如遇困难？可以加入我们超高质量的技术交流群，参与交流与讨论，更好的学习与进步！ 本文收录在了我正在连载的《Java新特性专栏》，该系列该用电子书的方式编写，如果想要沉浸式阅读学习的话，可以访问Web版本：www.didispace.com/java-featur… 再放大一些数据量，试试： @Benchmark public List streamToList() { return IntStream.range(1, 10000).boxed().toList(); } @Benchmark public List collectorsToList() { return IntStream.range(1, 10000).boxed().collect(Collectors.toList()); } @Benchmark public List streamToList() { return IntStream.range(1, 10000).boxed().toList(); }结果报告： Benchmark Mode Cnt Score Error Units BenchmarkStreamToList.collectorsToList thrpt 20 2.186 ± 0.162 ops/s BenchmarkStreamToList.collectorsToUnmodifiableList thrpt 20 2.184 ± 0.042 ops/s BenchmarkStreamToList.streamToList thrpt 20 3.538 ± 0.058 ops/s BenchmarkStreamToList.collectorsToList avgt 20 0.426 ± 0.004 s/op BenchmarkStreamToList.collectorsToUnmodifiableList avgt 20 0.469 ± 0.016 s/op BenchmarkStreamToList.streamToList avgt 20 0.293 ± 0.008 s/op BenchmarkStreamToList.collectorsToList sample 58 0.448 ± 0.049 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.00 sample 0.414 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.50 sample 0.422 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.90 sample 0.458 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.95 sample 0.560 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.99 sample 1.160 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.999 sample 1.160 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p0.9999 sample 1.160 s/op BenchmarkStreamToList.collectorsToList:collectorsToList·p1.00 sample 1.160 s/op BenchmarkStreamToList.collectorsToUnmodifiableList sample 60 0.458 ± 0.004 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.00 sample 0.447 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.50 sample 0.455 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.90 sample 0.471 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.95 sample 0.482 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.99 sample 0.492 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.999 sample 0.492 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p0.9999 sample 0.492 s/op BenchmarkStreamToList.collectorsToUnmodifiableList:collectorsToUnmodifiableList·p1.00 sample 0.492 s/op BenchmarkStreamToList.streamToList sample 78 0.293 ± 0.012 s/op BenchmarkStreamToList.streamToList:streamToList·p0.00 sample 0.277 s/op BenchmarkStreamToList.streamToList:streamToList·p0.50 sample 0.284 s/op BenchmarkStreamToList.streamToList:streamToList·p0.90 sample 0.309 s/op BenchmarkStreamToList.streamToList:streamToList·p0.95 sample 0.377 s/op BenchmarkStreamToList.streamToList:streamToList·p0.99 sample 0.459 s/op BenchmarkStreamToList.streamToList:streamToList·p0.999 sample 0.459 s/op BenchmarkStreamToList.streamToList:streamToList·p0.9999 sample 0.459 s/op BenchmarkStreamToList.streamToList:streamToList·p1.00 sample 0.459 s/op BenchmarkStreamToList.collectorsToList ss 20 0.474 ± 0.133 s/op BenchmarkStreamToList.collectorsToUnmodifiableList ss 20 0.493 ± 0.099 s/op BenchmarkStreamToList.streamToList ss 20 0.325 ± 0.056 s/op从报告中我们可以看到 吞吐量：streamToList > collectorsToList > collectorsToUnmodifiableList 平均耗时：streamToList > collectorsToList > collectorsToUnmodifiableList p0.9999耗时：streamToList > collectorsToUnmodifiableList > collectorsToList 冷启动耗时：streamToList > collectorsToList > collectorsToUnmodifiableList所以，即使集合内的元素增大，Stream.toList()的性能在各方面依然都要好于Collectors下的方法。 好了，今天的分享就到这里，你学会了吗？ 本期视频：www.bilibili.com/video/BV16Y… 欢迎关注我的公众号：程序猿DD。第一时间了解前沿行业消息、分享深度技术干货、获取优质学习资源 |
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