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) -> Doublepare(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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按降序对基本类型的数组进行排序
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