按降序对基本类型的数组进行排序 [英] Sort arrays of primitive types in descending order

问题描述

我有一大堆原始类型（双）。
如何按降序对元素进行排序？

I've got a large array of primitive types (double). How do I sort the elements in descending order?

不幸的是，Java API不支持对基本类型进行排序比较器。

Unfortunately the Java API doesn't support sorting of primitive types with a Comparator.

一种解决方法是排序然后反转：

One workaround would be to sort and then reverse:

double[] array = new double[1048576];
...
Arrays.sort(array);
// reverse the array
for (int i = 0; i < array.length / 2; i++) {
     // swap the elements
     double temp = array[i];
     array[i] = array[array.length - (i + 1)];
     array[array.length - (i + 1)] = temp;
}

这很慢 - 特别是如果数组已经排序得很好。

This is slow - particularly if the array is already sorted quite well.

什么是更好的选择？

推荐答案

Java Primitive 包括基于自定义比较器对原始数组进行排序的功能。使用它和Java 8，你的样本可以写成：

Java Primitive includes functionality for sorting primitive arrays based on a custom comparator. Using it, and Java 8, your sample could be written as:

double[] array = new double[1048576];
...
Primitive.sort(array, (d1, d2) -> Double.compare(d2, d1), false);

如果您使用的是Maven，可以将其包括在内：

If you're using Maven, you can include it with:

<dependency>
    <groupId>net.mintern</groupId>
    <artifactId>primitive</artifactId>
    <version>1.2.1</version>
</dependency>

当您传递 false 作为第三个参数时到 sort ，它使用不稳定的排序，简单编辑Java的内置双枢轴快速排序。这意味着速度应该接近内置排序的速度。

When you pass false as the third argument to sort, it uses an unstable sort, a simple edit of Java's built-in dual-pivot quicksort. This means that the speed should be close to that of built-in sorting.

完全披露：我编写了Java Primitive库。

Full disclosure: I wrote the Java Primitive library.

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