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When we put key-value pair in HashMap this could happen the hashcode of two keys could be same then how in this condition storing and retrieval of key-value will be handled.
Update
What I understand so far is that if two object key has same hash code then both key objects will be stored in same bucket and when I will say get(key) then out of two objects with matching hashcode which element to fetch is decided by object.equals().
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The only way to avoid (or rather minimize) collisions is to create a hash function that creates the best possible distribution of values throughout the HashMap. Depending on the density of your HashMap and the quality of your hash code , collisions are almost inevitable, hence the need to override the two methods.
Following are the collision resolution techniques used: Open Hashing (Separate chaining) Closed Hashing (Open Addressing) Liner Probing. Quadratic probing.
Hash collision is resolved by open addressing with linear probing. Since CodeMonk and Hashing are hashed to the same index i.e. 2, store Hashing at 3 as the interval between successive probes is 1. There are no more than 20 elements in the data set. Hash function will return an integer from 0 to 19.
One method for resolving collisions looks into the hash table and tries to find another open slot to hold the item that caused the collision. A simple way to do this is to start at the original hash value position and then move in a sequential manner through the slots until we encounter the first slot that is empty.
When you want to retrieve some object from hashmap and there exists several objects with the same hashcode, java will call equals() to determine the right object.
That is why it is so important to override equals() when overriding hashCode().
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Each bucket is represented by a linked list, so there is no limit, other than heap space, on the number of entries in a bucket. There are fewer buckets than possible hashCode results, so multiple hash codes are mapped to the same bucket, not just keys with the same hashCode.
A hashCode() with many collisions, or a HashMap with too few buckets, can make some linked lists long. Good performance depends on short linked lists, because the final stage in a look up is a linear scan of one of the linked lists.
I agree with the previous answer that a match depends on both equals() and hashCode().
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