如何使一个“与equals不一致”的TreeSet(How to have a TreeSet which is “inconsistent with equals”)

 我已经阅读了很多关于TreeSet，Comparable / Comparator Interfaces，equals，compareTo，compare方法的帖子，我知道API说你必须让你的命令“与equals一致”或者可能发生奇怪的事情。 
 
 但在我的情况下，我认为这是一个相当普遍的情况，我确实需要一个“与equals不一致”的TreeSet排序。 
 
 假设我们正在进行某种启发式搜索，并且我们正在从根（初始）状态开始扩展（或生成）新状态。 我们将新的（扩展/生成）状态放入TreeSet中，我们通常称之为打开列表。 我们想使用TreeSet容器，因为我们不希望在打开的列表中有重复的状态。 
 
 生成/扩展的每个状态都由成本函数评估，并给出显示状态质量的启发式值。 我们想要按此值排序的TreeSet（打开列表）。 我们希望在TreeSet的顶部具有最佳状态（具有最佳成本值）。 
 
 现在问题来了。 为了适应成本值的排序，我们需要为TreeSet提供一个比较成本值的比较器。 但是，两个不同的状态可以具有相同的成本/启发式值。 我希望在我的公开名单上有这两种状态，因为它们并不“平等”。 但比较器需要从比较方法返回0，因为它们具有相同的成本值。 因此，具有相同成本值的不同状态将不会插入到列表中。 
 
 我想举一个简单的例子来说明这一点更容易理解。 假设我们的状态是显示二进制数据的字符串，而cost函数计算字符串中“1”的数量。 
 
 让我们说这些是生成的状态和它们各自的成本值。 
 
  No  State       Cost 
  1   01001001     3
  2   01101001     4
  3   10001001     3
  4   01001111     5
 
 正如您所看到的，这4个州都不同。 他们“不平等”。 但即使state-1和state-3不同，它们也具有相同的成本值“3”。 因此，当我们按成本订购TreeSet时，state-3将不会添加到TreeSet中，因为已经存在具有相同成本值的元素。 但是我们需要将该状态添加到列表中，因为它是完全有效的，不同的新状态。 
 
 我怎样才能克服这个问题？ 
 
 谢谢。 

I have read numerous posts about TreeSets, Comparable/Comparator Interfaces, equals, compareTo, compare methods and I know that API says you have to make your ordering "consistent with equals" or weird things might happen.
 
But in my case and I think this is a fairly general case, I really do need a TreeSet ordering which is "inconsistent with equals". 
 
Lets say we are doing some kind of heuristic search and we are expanding (or generating) new states starting from a root(initial) state. And we put new (expanded/generated) states into a TreeSet which we usually call open list. We would like to use the TreeSet container because we dont want duplicate states in our open list.
 
Every state generated/expanded is evaluated by a cost function and given a heuristic value which shows the quality of the state. We want the TreeSet (open list) ordered by this value. We want to have the best states (which has the best cost value) at the top of the TreeSet. 
 
Now here comes the problem. To accommodate the ordering by cost value we need to give the TreeSet a comparator which compares the cost values. But, two different states can have the same cost/heuristic value. I want to have both of these states on my open list because they are not "equal". But comparator needs to return 0 from the compare method because they have the same cost value. And because this, different states with the same cost value will not be inserted into the list. 
 
I want to give a simple example to make this more understandable. Lets say our states are strings showing binary data and the cost function counts the number of "1"s in the string.
 
Lets say these are the generated states and their respective cost values.
 
  No  State       Cost 
  1   01001001     3
  2   01101001     4
  3   10001001     3
  4   01001111     5
 
As you can see all these 4 states are different. They are "not equal". But even though state-1 and state-3 are different, they have the same cost value "3". So when we order our TreeSet by cost, state-3 will not be added to the TreeSet because there is already an element with the same cost value. But we need that state to be added to the list because it is perfectly valid, different, new state.
 
How can I overcome this problem?
 
Thanks.

原文：https://stackoverflow.com/questions/26019123