具有空值的比较器 [英] comparator with null values

问题描述

我们有一些代码根据坐标之间的距离对地址列表进行排序。这是通过collections.sort和自定义比较器完成的。

We have some code wich sorts a list of addresses based on the distance between their coordinates. this is done through collections.sort with a custom comparator.

但是，有时会在列表中出现没有坐标的地址，从而导致出现NullPointerException。我最初的想法是让比较器返回0作为地址的距离，其中至少有一个坐标为空。我担心这可能会导致列表中'有效'元素的顺序损坏。

However from time to time an adress without coordinates is in the list causing a NullPointerException. My initial idea to fix this was to have the comparator return 0 as dististance for addresses where at least one of the coordinates is null. I fear this might lead to corruption of the order the 'valid' elements in the list.

所以在比较器ok中返回空数据的'0'值，或者有更清洁的方法来解决这个问题。

so is returning a '0' values for null data in a comparator ok, or is there a cleaner way to resolve this.

推荐答案

处理它像 null 意味着无限远。因此：

Handle it like null means infinitely far away. Thus:

• comp（1234，null）== -1


• comp（null，null）== 0


• comp（null ，1234）== 1

• comp(1234, null) == -1
• comp(null, null) == 0
• comp(null, 1234) == 1

通过这种方式，您可获得一致的订购。

With this, you get a consistent ordering.

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