Navigable map is a sorted map that can be iterated over in descending order as well as ascending order. Navigable maps are described by the NavigableMap interface, whose generic type is NavigableMap, which extends SortedMap.
TreeMap is an example of a navigable map.
import java.util.Iterator;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.TreeMap;
public class Main {
public static void main(String[] args) {
NavigableMap navigableMap = new TreeMap();
String[] letters = { "a", "b", "c" };
int[] ints = { 3, 2, 1 };
for (int i = 0; i < letters.length; i++){
navigableMap.put(letters[i], ints[i]);
}
System.out.println("Map = " + navigableMap);
NavigableSet ns = navigableMap.navigableKeySet();
Iterator iter = ns.iterator();
while (iter.hasNext()){
System.out.print(iter.next() + " ");
}
System.out.println();
ns = navigableMap.descendingKeySet();
iter = ns.iterator();
while (iter.hasNext()){
System.out.print(iter.next() + " ");
}
System.out.println();
System.out.println("First entry = " + navigableMap.firstEntry());
System.out.println("Last entry = " + navigableMap.lastEntry());
System.out.println("Entry < a is " + navigableMap.lowerEntry("a"));
System.out.println("Entry > c is " + navigableMap.higherEntry("c"));
System.out.println("Poll first entry: " + navigableMap.pollFirstEntry());
System.out.println("Map = " + navigableMap);
System.out.println("Poll last entry: " + navigableMap.pollLastEntry());
System.out.println("Map = " + navigableMap);
}
}