Goals:

• Understand how to organize code into a package.
• Understand more about the Relation and Set ADTs from CS 101
• Understand how to use Java collection objects imported from java.util.*
• Understand the basics of a hash table and the relevance of Java's hashCode() method.
• Understand basic String processing
• Know how to write console output using System.out instead of Transcript.
• Appreciate the value of the Iterator pattern and understand its usage in Java.

Before starting:

• Read over the entire lab. We really mean it this time.
• Run the sample solution
• Review the Relation and Set ADTs from CS101.
• Browse the documentation , to gain an understaning of the objects' interrelation as well as their methods.

Helpful resources:

• The myriad methods that can be called on a String object. These might be useful for getting rid of punctuation in Strings, converting Strings to lower case, etc.
• Lecture notes and references on package stuff:
  • Language Spec
  • Tutorial
  
  
• Lecture notes and references on collection objects:
  • Collections Tutorial
  • java.util overview
  • Interfaces and Implementations
  • HashMap ( JavaDoc )
  • Examples from IEEE workshop paper on real-time hashing
  
  
• StringTokenizer API (for breaking a Phrase into Words)
• Set interface tutorial and the HashSet implementation
• Why did Java move from Enumeration to Iterator ?
• Useful Swing components to start examining for part b:
  • JTextField ( JavaDoc )
  • JScrollPane ( JavaDoc )

Overview:

In CS101 you studied the Relation and Set ADTs. Relation implements a function or a map, and a Set is a duplicate-free collection of objects. In this lab you will use both of those ADTs but in the form of implementations already available in java.util.

Specifically, you will implement a KWIC (KeyWord In Context) object and to place it and its supporting objects in a package called kwic.

Supose you wanted to search a document for all phrases that include a given word, say "swordfish". There are two approaches that could be used in this endeavor:

1. Once "swordfish" is supplied, a computer could search the document and return each phrase that contains that word. Every time a word is supplied, the entire document is scanned to find matching phrases.
2. The document could be preprocessed offline , in anticipation of the need for search. When "swordfish" is supplied, the result is already computed and simply returned.

• How stable is the document? Do phrases come and go or is the document relatively constant?
• How often is the same word supplied for a search? Would "swordfish" be supplied many times or just once?

We shall assume that offline preprocessing pays off, and that it would be expensive to search the document each time a word is supplied. As an analogy, consider a search using Google . Imagine how slow it would be for Google to search the entire WWW each time you ask it to find a word. (Note: It takes about a month for Google to crawl the web currently!)

As an example for this lab, consider the following phrases:

• Swordfish goes well with pasta; the pasta should not be overcooked.
• The password for entry to the castle is: "swordfish".
• All's well that ends well.

Suggested implementation:

1. Make a directory for your Lab 2a stuff.
2. Save the Demo.java file there.
3. Make a kwic directory into which your classes will go.
4. Save the WordCanonical.java file there.
5. Type in stubs for the other classes found in the documentation
6. Complete and test the DefaultWordFilter class. You can just return the input string for now.
7. Complete and test the Word class.
   • Note the two constructors
   • Note the use of a DefaultWordFilter.
8. Complete and test the Phrase class.
9. Complete and test the KWIC class.

What To Turn In:

For every CS102 lab you turn in, you should fill in a cover sheet and staple it on the front of your lab. Attach a paper printout of the following:

1. All classes written for this lab.
2. Output from the class test Demo2a.java .

If you need help printing, ask a TA or refer to the help homepage, which has detailed instructions for how to print from the labs.