Java Hashtable class

• 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 implements the Map interface and extends Dictionary class.
• It contains only unique elements.
• It may have not have any null key or value.
• It is synchronized.

Example of Hashtable:

1. import java.util.*;  
2. class TestCollection16{  
3.  public static void main(String args[]){  
4.    
5.   Hashtable<Integer,String> hm=new Hashtable<Integer,String>();  
6.   
7.   hm.put(100,"Amit");  
8.   hm.put(102,"Ravi");  
9.   hm.put(101,"Vijay");  
10.   hm.put(103,"Rahul");  
11.   
12.   for(Map.Entry m:hm.entrySet()){  
13.    System.out.println(m.getKey()+" "+m.getValue());  
14.   }  
15.  }  
16. }  

Output:103 Rahul
       102 Ravi
       101 Vijay
       100 Amit