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Java / Map and its implementations

How Remove method works internally in Java HashMap?

HashMap remove method calls removeEntryForKey method internally, which calculate the final hashValue of the key object, and then use that hashValue in the indexFor(int,int) method to find the first entry object in the appropriate bucket.

Since bucket is a LinkedList we start traversing from the first entry object which we retrieved indexFor method in the bucket. For each entry object in the bucket we compare whether hashValue and the key is equal to the calculated hashValue in the first step and the key passed as a parameter in the remove(key) method.

If desired Entry object is found , then we remove that single entry object from the LinkedList. Removing a single Entry object from the LinkedList is implemented just like removing a single object from the LinkedList.

Entry object returned by the removeEntryForKey method is then stored in the local variable e of type Entry in the remove(key) method. Return the removed entry if it is not null else return null.

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