Collecting Objects - Beginning Java 7 - page 515

Table 5-11 ' s methods describe the NavigableMap equivalents of the Navig-
ableSet methodspresentedin Table5-4 ,andevenreturn NavigableSet instances
in two instances.
Listing 5-25 demonstrates a navigable map based on a tree map.
Listing 5-25. Navigating a map of (bird, count within a small acreage) entries
import java.util.Iterator;
import java.util.NavigableMap;
import java.util.NavigableSet;