什么是比较合同? [英] What is the compare contract?

问题描述

我的Java代码引发了以下异常:

My java code threw the following exception:

java.lang.IllegalArgumentException: Comparison method violates its general contract!

我研究了StackOverflow上的消息，发现了几个问题，这些问题张贴了他们写得不好的比较方法，但是我想知道合同写在哪里，以及关于比较方法必须做什么的确切说明.

I researched the message on StackOverflow and found several questions that posted their poorly written compare methods, but I was wondering where the contract is written and what exactly does it state regarding what the compare method must do.

推荐答案

类似

实现者必须确保sgn(compare(x，y))==-sgn(compare(y，x))表示所有x和y.(这意味着，当且仅当compare(y，x)抛出一个异常时，compare(x，y)必须抛出一个异常.例外.)

The implementor must ensure that sgn(compare(x, y)) == -sgn(compare(y, x)) for all x and y. (This implies that compare(x, y) must throw an exception if and only if compare(y, x) throws an exception.)

实现者还必须确保该关系是可传递的:(((compare(x，y)> 0)&&(compare(y，z)> 0))表示compare(x，z)> 0.

The implementor must also ensure that the relation is transitive: ((compare(x, y)>0) && (compare(y, z)>0)) implies compare(x, z)>0.

最后，实现者必须确保compare(x，y)== 0意味着所有z的sgn(compare(x，z))== sgn(compare(y，z)).

Finally, the implementor must ensure that compare(x, y)==0 implies that sgn(compare(x, z))==sgn(compare(y, z)) for all z.

通常是这种情况，但不是严格要求(compare(x，y)== 0)==(x.equals(y)).一般来说，任何比较器违反此条件应清楚地表明这一事实.这推荐的语言是注意:此比较器强加了以下命令:与等式不一致."

It is generally the case, but not strictly required that (compare(x, y)==0) == (x.equals(y)). Generally speaking, any comparator that violates this condition should clearly indicate this fact. The recommended language is "Note: this comparator imposes orderings that are inconsistent with equals."

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