SortedMap

SortedMap: interface extends Map. It ensures that the entries are maintained in ascending key order
Several methods throw a NoSuchElementException when no items are in the invoking map. A ClassCastException is thrown when an object is incompatible with the elements in a map. A NullPointerException is thrown if an attempt is made to use a null object when null is not allowed in the map.
The methods declared by SortedMap are summarized in the following table:

SN	Methods with Description
1	Comparator comparator( ) Returns the invoking sorted map's comparator. If the natural ordering is used for the invoking map, null is returned.
2	Object firstKey( ) Returns the first key in the invoking map.
3	SortedMap headMap(Object end) Returns a sorted map for those map entries with keys that are less than end.
4	Object lastKey( ) Returns the last key in the invoking map.
5	SortedMap subMap(Object start, Object end) Returns a map containing those entries with keys that are greater than or equal to start and less than end
6	SortedMap tailMap(Object start) Returns a map containing those entries with keys that are greater than or equal to start.

Example:

SortedMap have its implementation in various classes like TreeMap, Following is the example to explain SortedMap functionlaity:

import java.util.*; class TreeMapDemo { public static void main(String args[]) { // Create a hash map TreeMap tm = new TreeMap(); // Put elements to the map tm.put("Zara", new Double(3434.34)); tm.put("Mahnaz", new Double(123.22)); tm.put("Ayan", new Double(1378.00)); tm.put("Daisy", new Double(99.22)); tm.put("Qadir", new Double(-19.08)); // Get a set of the entries Set set = tm.entrySet(); // Get an iterator Iterator i = set.iterator(); // Display elements while(i.hasNext()) { Map.Entry me = (Map.Entry)i.next(); System.out.print(me.getKey() + ": "); System.out.println(me.getValue()); } System.out.println(); // Deposit 1000 into Zara's account double balance = ((Double)tm.get("Zara")).doubleValue(); tm.put("Zara", new Double(balance + 1000)); System.out.println("Zara's new balance: " + tm.get("Zara")); } }

This would produce following result:

Ayan: 1378.0 Daisy 99.22 Mahnaz: 123.22 Qadir: -19.08 Zara: 3434.34 Zara.s current balance: 4434.34