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# NavigableSet, NavigableMap LHCF Methods

Ranch Hand
Posts: 163
I have some confusions on this tutorial about NavigableSetand NavigableMap.

Actually it's just the floor and the ceiling that's confusing me. They always seem to produce the parameter as the result.

NavigableSet:
Any
George
Hydro
Martin
Wallace

ceiling(Hydro) == Hydro.
floor(Hydro) == Hydro.

If we're talking about Strings in the Set, does ceiling and floor will always produce the same result as the parameter passed? I would like to know when will the results be different.

NavigableMap:
{5.64, Wallace}
{7.25, George}
{8.09, Hydro}
{9.00, Any}
{10.00, Martin}

ceilingKey(9.00) == 9.0
floorKey(9.00) == 9.0

Do you know any other resources with other examples for these particular methods? Thank you in advance!

Ranch Hand
Posts: 162

floor

E floor(E e)

Returns the greatest element in this set less than or equal to the given element, or null if there is no such element.

Parameters:
e - the value to match
Returns:
the greatest element less than or equal to e, or null if there is no such element

ceiling

E ceiling(E e)

Returns the least element in this set greater than or equal to the given element, or null if there is no such element.

Parameters:
e - the value to match
Returns:
the least element greater than or equal to e, or null if there is no such element

source:http://java.sun.com/javase/6/docs/api/java/util/NavigableSet.html

hope this helps