Data Structures and Algorithms in Java[1].pdf - Fulvio Frisone

an empty list-based map, we can easily use the separate chaining rule to perform
the fundamental map operations, as shown in Code Fragment 9.2.
Code Fragment 9.2: The fundamental methods of
the map ADT, implemented with a hash table that uses
separate chaining to resolve collisions among its n
entries.
For each fundamental map operation, involving a key k, the separate-chaining
approach delegates the handling of this operation to the miniature list-based map
stored at A [h(k)]. So, put(k, v) will scan this list looking for an entry with key
equal to k; if it finds one, it replaces its value with v, otherwise, it puts (k, v) at
the end of this list. Likewise, get(k) will search through this list until it reaches
the end or finds an entry with key equal to k. And remove(k) will perform a
similar search but additionally remove an entry after it is found. We can "get
away" with this simple list-based approach, because the spreading properties of
the hash function help keep each bucket's list small. Indeed, a good hash function
will try to minimize collisions as much as possible, which will imply that most of
our buckets are either empty or store just a single entry. This observation allows
us to make a slight change to our implementation so that, if a bucket A[i] is
empty, it stores null, and if A[i] stores just a single entry (k,v), we can simply
have A[i] point directly to the entry (k, v) rather than to a list-based map holding
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