Hashtable in Java

Hashtable in Java

Hashtable in Java

  • Java Hashtable class implements a Map Interface and extends Dictionary class
  • It is dual value pair collection in Java which stores <key,Value> pair in collection

The important points about Java Hashtable class are:

  • A Hashtable is an array of list. Each list is known as a bucket. The position of bucket is identified by calling the hashcode() method.
  • A Hashtable contains values based on the key.
  • It contains only unique elements.
  • Value and key should not be NULL.
  • It is synchronized. (Thread safe, can be used in multi threading environment).

Syntax

  Hashtable<Integer,String> hm=new Hashtable<Integer,String>();  

Example

package Mypkg;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class MAPex {
            /**
             * @param args
             */
            public static void main(String[] args) {
                        // TODO Auto-generated method stub
                System.out.println("***********************************");
                Hashtable<Integer,String> hm=new Hashtable<Integer,String>(); 
                hm.put(100,"Besant"); 
                hm.put(600,"Chennai"); 
                hm.put(200,"Technology"); 
                hm.put(103,"Bangalore"); 
                            for(Map.Entry m:hm.entrySet()){ 
                 System.out.println(m.getKey()+"-> "+m.getValue()); 
                } 
                System.out.println("***********************************");
}
}

Output

*********************************

600-> Chennai

103-> Bangalore

200-> Technology

100-> Besant

***********************************

Methods of Hashtable

Method nameDescription
void clear()Removes all the key-value pairs.
boolean containsKey(Object key)Returns true, if the Hashtable contains a value for the specified key.
boolean containsValue(Object value)Returns true, if the Hashtable maps a value for the specified key.
Enumeration<V> elements()Iterates  the values in the Hashtable.
Object get(Object key)Returns the value to which the specified key is mapped, or null if the map contains no mapping for the key.
Set entrySet()Returns a Sets which contains the key-value pairs of the map.
int hashCode()Returns the hash code value for the Hashtable
boolean isEmpty()Tests if this Hashtable maps no key value pairs.
Enumeration<K> keys()Returns the keys mapped in the Hashtable with the type Enumeration.
Set<K> keySet()Returns the keys mapped in the Hashtable as the type Set.
Value put(K key, V value)Maps the specified key with the specified value in the Hashtable.
void rehash()Increases the size of the Hashtable and re-maps the key values according to the new size.
V replace(K key, V value)Replaces the value of the specified key with the value specified.
int size()Returns the number of key-value pairs in the map.
Value remove(Object key)Removes the key value pair for the specified key from the map if it is present.

Besant Technologies – Chennai & Bangalore Branch Locations

Besant Technologies - Velachery Branch
Plot No. 119, No.8, 11th Main road, Vijaya nagar,
Velachery, Chennai - 600 042
Tamil Nadu, India
Landmark - Reliance Digital Opposite Street
+91-996 252 8294 / 996 252 8293

Besant Technologies - Tambaram Branch
No.2A, 1st Floor, Duraisami Reddy Street,
West Tambaram, Chennai - 600 045
Tamil Nadu, India
Landmark - Near By Passport Seva
+91-996 250 4283

Besant Technologies - OMR Branch
No. 5/318, 2nd Floor, Sri Sowdeswari Nagar,
OMR, Okkiyam Thoraipakkam, Chennai - 600 097
Tamil Nadu, India
Landmark - Behind Okkiyampet Bus Stop,
+91-887 038 4333

Besant Technologies - Porur Branch
No. 180/84, 1st Floor, Karnataka Bank Building
Trunk Road, Porur,
Chennai - 600 116
Tamilnadu, India
Land Mark: Opposite to Gopalakrishna Theatre
+91-755 022 6990

Besant Technologies - Anna Nagar Branch
Plot No:1371, 28th street kambar colony,
I Block, Anna Nagar ,
Chennai - 600 040
Tamil Nadu, India
Landmark - Behind Reliance Fresh
+91-938 404 0493

Besant Technologies - T.Nagar Branch
Old No:146/2- New No: 48,
Habibullah Road,T.Nagar,
Chennai - 600 017
Tamil Nadu, India
Landmark - Opposite to SGS Sabha
+91-984 025 8377

Besant Technologies - Thiruvanmiyur Branch
22/67, 1st Floor,
North mada street, Kamaraj Nagar
Thiruvanmiyur, Chennai 600041
Tamil Nadu, India
Landmark - Above Thiruvanmiyur ICICI Bank
+91-938 404 0493

Besant Technologies - Siruseri Branch
No. 4/76, Ambedkar Street,
OMR Road, Egatoor, Navallur,
Siruseri, Chennai 600130
Tamil Nadu, India
Landmark - Near Navallur Toll Gate, Next to Yamaha Showroom
+91-7338 810 550

Besant Technologies - Maraimalai Nagar Branch
No.37, Ground Floor,
Thiruvalluvar Salai,
Maraimalai Nagar,Chennai 603209
Tamil Nadu, India
Landmark - Near to Maraimalai Nagar Arch
+91-979 123 7373

Besant Technologies - BTM Layout Branch
No 2, Ground floor,
29th Main Road, Kuvempu Nagar,BTM Layout 2nd Coming from Silkboard, take left at AXA company signal,
Stage, Bangalore - 560 076
Karnataka, India
Landmark - Next to OI Play School
+91-762 494 1772 / 74

Besant Technologies - Marathahalli Branch
No. 43/2, 2nd Floor, VMR Arcade,
Varthur Main Road, Silver Springs Layout,
Munnekollal, Marathahalli, Bengaluru - 560037
Karnataka, India
Landmark - Near Kundalahalli Gate Signal
+91-910 812 6341

Besant Technologies - Rajaji Nagar Branch
No. 309/43, JRS Ecstasy, First Floor,
59th Cross, 3rd Block, Bashyam Circle,
Rajaji Nagar, Bangalore - 560 010
Karnataka, India
Landmark - Near Bashyam Circle
+91- 734 916 0004

Besant Technologies - Jaya Nagar Branch
No. 2nd Floor,1575,11th Main Road,
4th T-Block, Pattabhirama Nagar, Jaya Nagar,
Bangalore-560041
karnataka, India
Land Mark: Opposite to Shanthi Nursing Home
+91-733 783 7626

Besant Technologies - Kalyan Nagar Branch
No.513, 4th Cross Rd
2nd Block, HRBR Layout, Kalyan Nagar,
Bangalore-560043
karnataka, India
Land Mark: Opposite to kalayan nagar Axis Bank
+91-938 404 0495

Besant Technologies - Electronic City Branch
No. 7, 3rd Floor, Ganga Enclave,
Neeladri Road, Karuna Nagar, Doddathoguru Village,
Electronics City Phase 1, Electronic City,
Bangalore - 560100, karnataka, India
Land Mark: Adjacent to HDFC Bank and State Bank Of India
+91-782 392 2180

Besant Technologies - Indira Nagar Branch
No.54, 1st Floor,
5th Main kodihalli,
Bengaluru, Karnataka 560008, India
Landmark: Behind Leela Palace Hotel,
+91-910 812 6339

Besant Technologies - HSR Layout Branch
Plot No. 2799 & 2800, 27th Main,
1st Sector, HSR Layout,
Bengaluru, Karnataka 560102, India
+91-733 783 7626