Answer / sivaprasad

1)In Array We Can Add any datatype value,Every item in
arraylist is treated as object.
2)Hashtable is collection of key,value pairs
i)Key Can be any datatype
ii)Key Cannot be null refrrence
iii)but value can be null referrence

Retrieving by key in Hashtable is faster than retrieving in
Arraylist,
Example of Arraylist:
Arraylist ar = new Arraylist();
ar.add("X");
ar.add(1);
ar.add(2);
Now if we Retrieve from Arraylist like
foreach(string str in ar)
{

}
It will Compile but it will give Runtime
Error,because '1' and '2' in Arraylist are integers.

Example Hashtable:
Hashtable ht = new Hashtable();
ht.add(1,"sample");
ht.add("2","Test");
ht.add(3,4);
foreach(Dictionaryentry dr in ht.keys.values)
{
Console.Writeline(dr.keys + "=" + dr.values);
}

The Above Code wont give any runtime Error Because We
are iterating through DictionaryEntries(Hashtable
implements IDictionary) it is Collection of Key/Value Pairs

Answer / devendra kumar

in array list we can only add items to the list but in hash
list we can add data with the key .

Answer / digvijay

Hi,

Arraylist is a item collection of different datatypes.
Hashtable is a collection key value pair.

Array list is a list
In this we can add items to the list
Here we can add any datatype value, every item in arraylist
is treated as object

Hash table is a map
Here we can add data with the key
Retriving data in hash is faster then in array list.

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