When using Java’s Map implementations, it is sometimes common to invoke the Map ‘s get (Object) method and to react differently based on whether the value returned is null or not.

This tutorial explains how a Java HashMap works internally and explores the challenges of implementing it, including buckets, collisions and hash codes.

HashMap vs. Hashtable similarities Both the Hashtable and HashMap implement the Map interface and both share the same set of methods used to add, remove and manipulate elements of a key-value, ...