java 8中.stream（）的默认实现是什么？ [英] What is the default implementation of .stream() in java 8?

问题描述

它只是说：

返回以此集合为源的顺序Stream。

Returns a sequential Stream with this collection as its source.

当spliterator（）方法不能
返回一个IMMUTABLE，CONCURRENT或后期绑定的spliterator时，应该重写此方法。
（有关详细信息，请参阅spliterator（）。）

This method should be overridden when the spliterator() method cannot return a spliterator that is IMMUTABLE, CONCURRENT, or late-binding. (See spliterator() for details.)

但我找不到任何显示其创建和返回方式的代码新流。

But I can't find any code showing how it creates and returns the new Stream.

double average = roster
.stream()
.filter(p -> p.getGender() == Person.Sex.MALE)
.mapToInt(Person::getAge)`enter code here`
.average()
.getAsDouble();

• 名册是一个列表< Person> 实例> ArrayList< Person>


• 人是一个代表一个人的简单类


• roster is a List<Person> instance of ArrayList<Person>
• Person is a simple class that represents a person

推荐答案

基本上整个流实现都是私有的，所以你不会在docs.oracle.com上看到任何东西。

Basically the whole stream implementation is package private so you won't get anything showing up at docs.oracle.com.

但是看一看这里的源代码： http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/java/util/stream

But take a look a look at the source code here: http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/java/util/stream

您可以从StreamSupport开始，大多数类都使用它来创建各种流。

You can start with StreamSupport which most classes uses to create the various streams.

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