Java 8供应商&消费者对外行的解释 [英] Java 8 Supplier & Consumer explanation for the layperson

问题描述

作为一名学习Java的非Java程序员，我正在阅读 Supplier 和 Consumer 接口。我无法围绕他们的用法和意义。您何时以及为何使用这些界面？有人可以给我一个简单的非专业人士的例子......我发现Doc的例子不够简洁，无法理解。

As a non-Java programmer learning Java, I am reading about Supplier and Consumer interfaces at the moment. And I can't wrap my head around their usage and meaning. When and why you would use these interfaces? Can someone give me a simple layperson example of this… I'm finding the Doc examples not succinct enough for my understanding.

推荐答案

这是供应商：

public Integer getInteger() {
    return new Random().nextInt();
}

这是消费者：

public void sum(Integer a, Integer b) {
    System.out.println(a + b);
}

因此，在外行条款中，供应商是一种返回某些价值的方法（如在它的回报值）。然而，消费者是一种消耗某些价值的方法（如在方法参数中），并对它们进行一些操作。

So in layman terms, a supplier is a method that returns some value (as in it's return value). Whereas, a consumer is a method that consumes some value (as in method argument), and does some operations on them.

那些将转变为类似的东西：

Those will transform to something like these:

// new operator itself is a supplier, of the reference to the newly created object
Supplier<List<String>> listSupplier = ArrayList::new;
Consumer<String> printConsumer = a1 -> System.out.println(a1);
BiConsumer<Integer, Integer> sumConsumer = (a1, a2) -> System.out.println(a1 + a2);

至于用法，最基本的例子是： Stream＃forEach（消费者） 方法。它需要一个Consumer，它消耗你正在迭代的流中的元素，并对它们中的每一个执行一些操作。可能会打印出来。

As for usage, the very basic example would be: Stream#forEach(Consumer) method. It takes a Consumer, which consumes the element from the stream you're iterating upon, and performs some action on each of them. Probably print them.

Consumer<String> stringConsumer = (s) -> System.out.println(s.length());
Arrays.asList("ab", "abc", "a", "abcd").stream().forEach(stringConsumer);

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