import java.io.*;
class Hashtable
{
public static void main (String args[])
{
Hashtable h=new hahtable();
h.add("dil");
h.add("ppp");
h.add("kkk");
System.out.println("the value of h is "+h);
System.out.println("the value of size is"+h.size());
}
}
import java.io.*;
class Hashmap
{
public static void main(String args[])
{
h.put("1","kkk");
h.put("2","ppp");
System.out.println("the value of h is"+h);
}
}
suppose if we use the haahtable  then the we have to use 
Enumeration concept and suppose if we use the HashMap then 
we have to use Iterator concept.

** HASH MAP **
import java.util.*;
class myhashmap
{
public static void main(strings args[])
{
HashMap map=new HashMap();
map.put("fname","abc");
map.put("email","abc@yahoo.com");
map.put("age",21);
map.put("","");
System.out.println(map.get("fname"));
System.out.println(map.get("age"));
}
}

** Hash Table **

import java.util.*;
class testhashtable
{
public static void main(string args[])
{
Hashtable<String,Integer> num=new Hashtable<String.Integer>
();
num.put("one",new Integer(1));
num.put("two",new.Integer(2));
Integer n=(Integer) num.get("two");
if(n!=null)
{
System.out.println("two="+n);
}
}
}


Difference b/w two is...Hash Map allows NULL values whereas 
Hash table not.