2. What will happen if hashcode only returns a constant? How will it affect the internal working of the HashMap?

Question

Accepted Answer

If hashcode returns a constant, all elements will be stored in the same bucket, resulting in poor performance.

All elements will be stored in the same bucket of the HashMap.
This will lead to poor performance as the HashMap will essentially become a linked list.
Retrieving elements will take longer as the HashMap will have to iterate through the linked list to find the desired element.

Accepted Answer

If the hashCode() method always returns a constant value, it means that all the objects of the class will have the same hash code. In this case, when the HashMap is used to store objects of that class, all objects will be hashed to the same bucket.

This will result in poor performance of the HashMap as it will degenerate into a linked list with all objects hashing to the same bucket. Retrieving an object from such a linked list will require iterating over all the objects in that list, leading to a linear time complexity instead of the expected constant time complexity of a HashMap. This can lead to poor performance and in some cases, even cause the HashMap to become unusable.

Therefore, it is important that the hashCode() method returns a unique value for each object so that the objects are evenly distributed across the hash buckets, resulting in better performance of the HashMap.

2. What will happen if hashcode only returns a constant? How will it affect the internal working of the HashMap?

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