Store an object using a key in Hashtable

Question

Hi friends........

I am trying to store an object using a key in a Hashtable. And some other object already exists in that location, then what will happen? The existing object will be overwritten? Or the new object will be stored elsewhere?

Thanks..........

Vulpes · Answer

The keys in a Hashtable have to be unique. So if you try to 'put' a key/value pair to the Hashtable and the key already exists then the existing value for that key will be overwritten with the new value.

Vikas Mishra · Answer

Thanks Vulpes.....

Sam Hobbs · Answer

That is the way that hash tables typically work. If you do not want that then do not use a hash table. Hash tables were first used when computer memory and disk drive storage was expensive. They used to be exremely expensive compared to now. Typically when creating a hash table (adding items) you would first check to see if the hash currently exists and you have a way to store multiple items for a hash value. If the hash already exists with a different item then you would add the new item to the list of items for that hash value. When doing a lookup if there is more than one item for a hash then you would do a sequential search for the item. Using current technology it is usually more efficient for you and the computer to use a different collection type.

Satyapriya Nayak · Answer

Hi Vikas Agreed with @vulpes. The existing object will be overwritten and thus it will be lost. Thanks