Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Differences between TreeMap, HashMap and LinkedHashMap in Java
Details about TreeMap, HashMap and LinkedHashMap that help to differentiate them are given as follows −
TreeMap in Java
A TreeMap in Java is implemented using a Red-Black trees. It has key-value pairs i.e. keys that are associated with the values and the keys are ordered. A TreeMap can only have unique elements and cannot have a null key but have null elements.
A program that demonstrates this is given as follows −
Example
import java.util.*;
import java.lang.*;
import java.io.*;
public class Demo {
public static void main (String[] args) {
TreeMap<Integer, String> tMap = new TreeMap<Integer, String>();
int[] arr = {1, 3, 5, 7, 9};
for (int i : arr) {
tMap.put(i, Integer.toString(i));
}
for (int j: tMap.keySet()) {
System.out.print(j + " ");
}
}
}The output of the above program is as follows −
Output
1 3 5 7 9
HashMap in Java
A HashMap in Java is implemented using an array of linked lists. It has key-value pairs i.e. keys that are associated with the values and the keys are in arbitrary order. A HashMap can only have unique elements and can have only one null key but multiple null elements.
A program that demonstrates this is given as follows −
Example
import java.util.*;
import java.lang.*;
import java.io.*;
public class Demo {
public static void main (String[] args) {
HashMap<Integer, String> hMap = new HashMap<Integer, String>();
int[] arr = {1, 3, 5, 7, 9};
for (int i : arr) {
hMap.put(i, Integer.toString(i));
}
for (int j: hMap.keySet()) {
System.out.print(j + " ");
}
}
}The output of the above program is as follows −
Output
1 3 5 7 9
LinkedHashMap in Java
A LinkedHashMap in Java is implemented using doubly linked buckets. It has key-value pairs i.e. keys that are associated with the values and the keys are ordered by their insertion order. A LinkedHashMap can only have unique elements and can have only one null key but multiple null elements.
A program that demonstrates this is given as follows −
Example
import java.util.*;
import java.lang.*;
import java.io.*;
public class Demo {
public static void main (String[] args) {
LinkedHashMap<Integer, String> lhMap = new LinkedHashMap<Integer, String>();
int[] arr = {1, 3, 5, 7, 9};
for (int i : arr) {
lhMap.put(i, Integer.toString(i));
}
for (int j: lhMap.keySet()) {
System.out.print(j + " ");
}
}
}The output of the above program is as follows −
Output
1 3 5 7 9
279 Views
