Skip to main content

HashMap_Implementation

How to implement your own HashMap?
*********************************

   Hash Map is a implementaion of Map Interface.
   HashMap works on the principal of hashing.
-> Map.Entry interface - This interface gives a map entry (key-value pair).
   HashMap in Java stores both key and value object, in bucket, 
   as an object of Entry class which implements this nested interface Map.Entry.
-> hashCode() -HashMap provides put(key, value) for storing and get(key) method
   for retrieving Values from HashMap. When put() method is used to store (Key, Value) pair, 
   HashMap implementation calls hashcode on Key object to calculate a hash 
   that is used to find a bucket where Entry object will be stored. 
   When get() method is used to retrieve value, again key object is used to calculate a hash 
   which is used then to find a bucket where that particular key is stored.
-> equals() - equals() method is used to compare objects for equality.
   In case of HashMap key object is used for comparison, also using equals() method 
   Map knows how to handle hashing collision (hashing collision means more than 
   one key having the same hash value, thus assigned to the same bucket.
   In that case objects are stored in a linked list, 
   Where hashCode method helps in finding the bucket where that key is stored,
   equals method helps in finding the right key as there may be more than one key-value pair 
   stored in a single bucket.
** Bucket term used here is actually an index of array, that array is called table in HashMap 
   implementation. Thus table[0] is referred as bucket0, table[1] as bucket1 and so on.

So it is implementaion of HashMap

Comments

Post a Comment

Popular posts from this blog

Mockito interview Questions

1.       Question 1. What Is Mockito? Answer : Mockito allows creation of mock object for the purpose of Test Driven Development and Behavior Driven development. Unlike creating actual object, Mockito allows creation of fake object (external dependencies) which allows it to give consistent results to a given invocation. 2.       Question 2. Why Do We Need Mockito? What Are The Advantages? Answer : Mockito differentiates itself from the other testing framework by removing the expectation beforehand. So, by doing this, it reduces the coupling. Most of the testing framework works on the "expect-run-verify". Mockito allows it to make it "run-verify" framework. Mockito also provides annotation which allows to reduce the boilerplate code. 3.       Question 3. Can You Explain A Mockito Framework? Answer : In Mockito, you always check a particular class. The dependency in that class is injected using m...
2 comments
Read more

REST Methods

GET ============================================= HTTP GET method is used to **read** (or retrieve) a representation of a resource. According to the design of the HTTP specification, GET requests are used only to read data and not change it. Therefore, when used this way, they are considered safe. That is, they can be called without risk of data modification or corruption. Means calling it once has the same effect as calling it 10 times. Additionally, GET is idempotent which means that making multiple identical requests ends up having the same result as a single request. Donot expose unsafe operations via GET. It should never modify any resources on the server. Example: ------------    GET http://www.example.com/customers/12345/orders POST =================================== -> The POST verb is most-often utilized to **create** new resources. In particular, it's used to create subordinate resources. -> That is, subordinate to some other (e.g. parent) reso...
Post a Comment
Read more