Hash Tables

In this lab exercise you will complete the definition of a HashTable class. Specifically, you will:

Implement hash functions for integer and string keys
Implement a hash table search operation
Implement a hash table remove operation

Note that the HashTable class used in this exercise is not to be confused with the java.util.Hashtable class available in the Java Standard Library.

Before you begin, be sure you thoroughly understand the material presented on hash tables in lecture. The hash table Lecture Notes are available as a menu item to the left. In particular, see:

Hash Function Performance for hashing integers and strings
Hash Table Operations for implementing search and remove

Download this zipped NetBeans project folder — CS_2511_HashTable.zip — and unzip it in a suitable location.
Open the CS_2511_HashTable project in NetBeans.
Under Source Packages open the hashtest package and run the TestFrame.java class

Note that the integer and string keys always hash to zero — you will fix this

Under Test Packages open the hashtable package and run the HashTableTest.java class

Note that the testSearch and testRemove methods fail — you will fix this

You need to complete the following methods in the hashtable.HashTable class:

integerHash and stringHash: to exhibit good hashing performance for integer and string keys
search: to find and return the hash table element for a given key
remove: to remove a hash table element once it is found

After you have implemented integerHash and stringHash, test them by running the TestFrame.java class.

You should be able to insert random integers, random strings, and permuted strings with good hash function performance.

Good hash function performance would generally (but perhaps not always) show 1.0 or less for a standard deviation from the mean chain length after eleven inserts.