Easy learning with example program codes

SortedMap interface in java

SortedMap interface:

SortedMap interface extends Map interface. It maintains its entries in ascending key order.

Commonly used methods of SortedMap interface:

1. comparator(): Returns comparator for this sorted map. It returns null if the natural ordering is used for this map.

Syntax: public Comparator comparator().

2. firstKey(): Returns the first key in this map.

Syntax: public Object firstKey ( ).

3. headMap(Object end): Returns a SortedMap containing those elements less than end that are contained in this sorted map.

Syntax: public SortedMap headMap(Object end).

4. lastKey(): Returns the last key in this sorted map.

Syntax: public Object lastKey().

5. subMap(Object start, Object end): Returns a SortedMap containing those elements between start and end -1.

Syntax: public SortedMap subMap(Object start, Object end).

6. tailMap(Object start): Returns a map containing those entries with keys that are greater than or equal to start.

Syntax: public SortedMap tailMap(Object start)

 A simple example of TreeMap class to explain few methods of SortedMap interface.

import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
 * This class is used to show the TreeMap functionality.
 * @author codesjava
public class TreeMapTest {
	public static void main(String args[]){
		//Create TreeMap object.
		Map treeMap = new TreeMap();
		//Add objects to the TreeMap.
		treeMap.put(4, "Roxy");
		treeMap.put(2, "Sunil");
		treeMap.put(5, "Sandy");
		treeMap.put(1, "Munish");
		treeMap.put(3, "Pardeep");
		//Print the TreeMap object.
		System.out.println("TreeMap elements:");
		//Get iterator
		Set set=treeMap.entrySet();  
		Iterator iterator=set.iterator();  
		//Print the TreeMap elements using iterator.
		System.out.println("TreeMap elements using iterator:");
		   Map.Entry mapEntry=(Map.Entry);  
		   System.out.println("Key: " + mapEntry.getKey() + ", " +
		   		"Value: " + mapEntry.getValue());  


TreeMap elements:
{1=Munish, 2=Sunil, 3=Pardeep, 4=Roxy, 5=Sandy}
TreeMap elements using iterator:
Key: 1, Value: Munish
Key: 2, Value: Sunil
Key: 3, Value: Pardeep
Key: 4, Value: Roxy
Key: 5, Value: Sandy

Download this example.
Next Topic: Queue interface in java with example.
Previous Topic: Daemon thread in java in java with example.

Industrial Training

We offers Placement Oriented Training on Java, Spring, JSF, Hibernate, PHP, AngularJS, Angular 4, PLSQL, Oracle BI Publisher etc. We also provides Online training, please mail us at


We also provides the Development services for Website Development , Java Development, PHP Development, Android App Development etc. You can contact us on

Copyright © 2019 CodesJava Protection Status SiteMap Reference: Java Wiki