The interface java.util.SortedMap  is a subtype of the interface java.util.Map  It ensures that the entries are sorted in ascending order.

By default, items are scanned in ascending order from the small value to the large value. But it is also possible to browse the elements in descending order with the method TreeMap.descendingKeySet().

The API Collections of java has only one implementation of the interface SortedMap which is the java.util.TreeMap.

Example:

import java.util.*; 

public class SortedMap {

 public static void main(String[] args) {
 // create a TreeMap with a generic type
 TreeMap tm = new TreeMap(); 
 // fill treemap
 tm.put(1, "one"); 
 tm.put(2, "two"); 
 tm.put(3, "three"); 
 tm.put(4, "four"); 
 tm.put(5, "five"); 
 
 // retrieve all keys
 Set set = tm.entrySet(); 
 // retrieve iterator
 Iterator it = set.iterator(); 
 // browse treemap to display elements
 while(it.hasNext()) {
 Map.Entry mapentry = (Map.Entry)it.next(); 
 System.out.print("["+mapentry.getKey() +", "); 
 System.out.println(mapentry.getValue()+"]"); 
 }
 }
}

Results:

[1, one]
[2, two]
[3, three]
[4, four]
[5, five]