A sorted map sorts the map entries on keys based on either natural sort order or a custom sort order.
If the keys do not implement the Comparable interface, you must use a Comparator object to sort the entries.
Comparator object takes precedence over Comparable interface implemented on keys.
SortedMap interface inherited from the Map interface represented a sorted map.
TreeMap class implements the SortedMap interface.
The following code demonstrates how to use a SortedMap.
import java.util.SortedMap; import java.util.TreeMap; public class Main { public static void main(String[] args) { SortedMap<String, String> sMap = new TreeMap<>(); sMap.put("XML", "(342)113-1234"); sMap.put("Javascript", "(245)890-2345"); sMap.put("Json", "(205)678-3456"); sMap.put("Java", "(205)678-3456"); System.out.println("Sorted Map: " + sMap); // Get a sub map from Json (inclusive) to Java(exclusive) SortedMap<String, String> subMap = sMap.subMap("Json", "Java"); System.out.println("Sorted Submap from Json to Java(exclusive): " + subMap); // Get the first and last keys String firstKey = sMap.firstKey(); String lastKey = sMap.lastKey(); System.out.println("First Key: " + firstKey); System.out.println("Last key: " + lastKey); }/*from w ww . jav a2 s .co m*/ }