Java Reference
In-Depth Information
16. NavigableSet<Integer> subset = tree.subSet(new Integer(7), false,
new Integer(14), true);
17. for(Integer x : subset) {
18. System.out.print(x + “ “);
19. }
The previous statements break down as follows:
1.
Line 12 retrieves the
ceiling
of
10
, which is the smallest element greater than or
equal to
10
, which is
10
.
2.
Line 14 retrieves the
higher
of
10
, which is the smallest element greater than
10
,
which is
11
.
3.
Line 16 retrieves a subset of
tree
from
7
(noninclusive) and
14
(inclusive), which is
8
to
14
. The
for-each
loop on line 17 outputs this subset.
The output of the code is
ceiling of 10 = 10
floor of 10 = 11
8 9 10 11 12 13 14
The
TreeSet
class is the only class in the Collections Framework that implements the
NavigableSet
interface, and the exam requires basic knowledge of the methods listed
previously.
Now let's discuss the details of using the various types of maps in the Collections
Framework.
Maps
The
Map
interface is the parent interface of the various maps in the Collections Framework.
Maps are unique in that they do not implement the
Collection
interface like all the other
collections classes. The elements in a map are pairs of data: a value and a key that maps to
that value. Think of a map as an array, except instead of integer indexes to access elements,
you use a key that can be any data type. Maps do not allow duplicate keys, but there is no
restriction on duplicate values.
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