The idea behind a Map is to be able to find an object faster than a linear search. Using hashed keys to locate objects is a two-step process. Internally the Map stores objects as an array of arrays. The index for the first array is the hashcode() value of the key. This locates the second array which is searched linearly by using equals() to determine if the object is found.
HashSet: add(element), contains(element), iterator(), remove(element)
HashMap: put(key, val), get(key), keySet(), remove(key)