Logical inconsistence between Set and SortedSet interfaces (original) (raw)

Andrej Hollmann andrej.hollmann at gmx.de
Sun Jan 27 10:30:05 UTC 2013

Hello,

I want to add few products to the SortedSet and sort them by price. I add four different elements to TreeSet: ["salt",0.5$], ["milk", 1$], ["bread", 1$], ["bananas", 2$]

But at the end my TreeSet contains only three elements: ["salt",0.5$], ["bread", 1$], ["bananas", 2$]

The "bread" replaced the "milk" because it has the same price. I think ordering and equity are different aspects and should be separated. A logically correct SortedSet implementation should contain all four elements in ordered style. In that way SortedSet would be downward compatible to inherited Set interface.

To test my thinks I wrote my own SortedSet, which is based on TreeList from apache-collection and achieved desired results.

PS: With new SortedSet I can sort products by date, or supplier, ... . I just need to implement my own comparator and can be sure that added products will be not replaced by others because elements are the same during comparison.

Best Regards Andrej

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