Java Collections Part 6: Hashtable

Hashtable:

• A Hashtable is an array of list. Each list is known as a bucket. A Hashtable contains values based on the key.
• It contains only unique elements.
• It may have not have any null key or value.
• It is synchronized.

Code:

1. import java.util.*;  
2. public class HashTableDemo {  
3.   
4.     public static void main(String[] args) {  
5.         // TODO Auto-generated method stub  
6.           
7.         Hashtable<Integer, String>htable=new Hashtable<>();  
8.         htable.put(100, "Sujan");  
9.         htable.put(103, "Shakil");  
10.         htable.put(102, "Shimul");  
11.         htable.put(104, "Badhon");  
12.         print(htable);  
13.           
14.         htable.remove(104);  
15.         System.out.println("\nAfter removing:");  
16.         print(htable);  
17.           
18.         htable.replace(100, "Hasan Sujan");  
19.         htable.replace(102, "Hossain Shimul");  
20.         System.out.println("\nAfter replacing:");  
21.         print(htable);  
22.           
23.   
24.     }  
25.     public static void print(Hashtable<Integer, String>hashtable) {  
26.         for(Map.Entry m:hashtable.entrySet()){  
27.             System.out.println(m.getKey()+" "+m.getValue());  
28.         }  
29.     }  
30.   
31. }