本文介绍了在Java 8中反转比较器的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

我有一个ArrayList,并希望按降序排序。我用它 java.util.stream.Stream.sorted(Comparator)方法。以下是根据Java API的说明:

I have an ArrayList and want sort it in descending order. I use for it java.util.stream.Stream.sorted(Comparator) method. Here is a description according Java API:

此方法返回一个升序排序。我应该更改哪个参数,只是为了降序?

this methods return me a sort with ascending order. Which parameter should I change, just to have the descending order?

推荐答案

您可以使用有一个比较器强制反转自然排序。

You can use Comparator.reverseOrder() to have a comparator that imposes the reverse of the natural ordering.

如果要反转现有比较器的顺序,可以使用。

If you want to reverse the ordering of an existing comparator, you can use Comparator.reversed().

示例代码:

Stream.of(1, 4, 2, 5)
    .sorted(Comparator.reverseOrder()); 
    // stream is now [5, 4, 2, 1]

Stream.of("foo", "test", "a")
    .sorted(Comparator.comparingInt(String::length).reversed()); 
    // stream is now [test, foo, a], sorted by descending length

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09-17 01:32