Hashtable vs Hashmap
Hashtable and the hashmaps are the data structures in great use these days for most of the web-based applications and many other applications as well. These data structures help to sort the particular data according to its identifiers and the associated values. Basically these data structures help the developers to easily and efficiently sort most of the identifiers, also known as the keys, according to their values. This whole data structuring process is completed with the help of hash functions.
Hashtable Data Structure
In the field of computer science, the hashtable can be defined as the data structure, which has the ability to store the large data containing certain values, also named as keys. During the storing of these keys, they have to be paired with another list, known as the array. This entire pairing of keys with arrays is completed by using the hash functions.
The main purpose of these hash functions is to connect each of the assigned keys to its corresponding and matching value in the array. This process is known as hashing. And this is usually done after properly and completely formatting the hashtable, so that no irregular problems might come out during its working.
The complete and efficient working of the hashtable depends upon the efficiently designed and formatted hash functions. Usually an efficient hash function provides the complete check up on the keys and on the distribution in the list of array. Sometimes during the working of hash functions, hash collision might occur. The reason for this collision is the occurrence of two difference keys corresponding to the same value present in the array.
To solve this collision problem, the hash functions usually re-execute the complete data structure to find some different corresponding values for the same keys. Although the hashtable keys are fixed in number, but still the duplicate keys could also become the reason of such hash collisions.
Hashmap Data Structures
Although the hashtable and the hashmap are names given to the same data structure because their purpose of structuring is the same, but still there is a minute difference from which these can be easily classified. When talking about the hash functions and the hash collisions, then the hashmap also observes the similar things as that of the hashtable. Similarly, the values and keys present in the data structure are not serialized like that of the hashtable, where these values are serialized.
Difference between Hashtable and Hashmap:
The minute differences that exist between the hashtable and the hashmap data structures are given below:
• Hashmap allows the null values to be both of its keys and the values, while the hashtable do not allow the null values in data structuring.
• The hashmap cannot have the duplicate keys in it that is why there keys must only be mapped with only the single value. But the hashtable allows the duplicate keys in it.
• The hashmap contains an iterator which is basically fail-safe but the hashtable contains an enumerator, which is not fail-safe.
• The access to hashtable is synchronized on the table while the access to the hashmap is not synchronized.