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Date: Wed, 02 Aug 2006 14:43:38 +0800
From: Spark Shen <smallsmallorgan@gmail.com>
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To: harmony-dev@incubator.apache.org
Subject: [classlib][luni] Is fully comply with Comparator.compare(T,
 T) necessary
 (Re JIRA harmony 1026)
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I constructed a MockComparator as below:
public static class MockComparator<T> implements Comparator<T> {
        public int compare(T o1, T o2) {
            if(null == o1) return -1;
            if(o1.equals(o2)) {
                return 0;
            }
            return 1;
        }
}

This comparator regards null as the smallest object and TreeMap uses 
this Comparator as a null-tolerable comparator.
And this comparator is used to test the behavior of TreeMap.headMap() 
when the input is null.

Since null is recognized as smallest, the expected length of the 
returned SortedMap of TreeMap.headMap(null) will be zero.

My point here is that, under this situation, the MockComparator does not 
care about the order of non-null objects, it just know
null is always smaller. So, is it acceptable that - in this comparator, 
compare method does not judge the order of all the non-null objects?
(does not comply with doc of comparator.compare)

Best regards

-- 
Spark Shen
China Software Development Lab, IBM


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