在Java 8流中没有索引的原因是什么？ [英] What are the reasons for not having an index in Java 8 streams?

问题描述

我想知道Java 8流（ Stream< E> ），它们有以下方法：

I was wondering about the Java 8 streams (Stream<E>), they have the following methods:

• forEach（Consumer<？super E> action）


• forEachOrdered （消费者<？超级E>行动）

• forEach(Consumer<? super E> action)
• forEachOrdered(Consumer<? super E> action)

反对不提供以下签名的理由是什么？

What were the arguments against not supplying the following signature?

• forEachOrdered（BiConsumer< Integer，？super E> action）
  
  
  
  • 然后返回流中项目的索引和项目本身。
  
  

  有了这个重载，如果订购了流，就可以实际使用索引。

  With this overload it would be possible to actually use the index in case the stream was ordered.

  我真的好奇，看看有什么反对意见。

  I am really curious to see what the arguments are against it.

  编辑，实际上同样适用于 Iterator< E> with forEachRemaining ，可能还有更多的类。
  
  如果没有类提供这样的opti on，然后我怀疑它已被考虑用于Java 8并被拒绝。

  Edit, the same actually holds for Iterator<E> with forEachRemaining, and possibly more classes.
  If none of the classes provide such option, then I suspect it has been considered for Java 8 and denied.

  推荐答案

  索引每个元素需要按顺序分配索引。这会破坏并行操作的重点，因为每个操作都必须同步才能获得其索引。

  indexing every element requires a sequential assignment of the indexes. this would defeat the point of parallel operations, since each operation would have to synchronize to get its index.

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