Displaying Updated Stock Quotes

This paper describes how to extract stock quote data and display it with a dynamic update (using free, but delayed data streams). As a part of the architecture of the program, we make use of the observer, mediator and command design patterns. We also make use of the JTable and JTableModel. Finally we show how a multi-threaded update can be performed, using the web as a data source. The methodology for converting the web data source into internal data structures is based on using HTML as input. This type of screen scraping has become a popular means of inputting data into programs. Simple string manipulation techniques are shown to be adequit for these types of well-formed data streams. Stock price data is generally available on the web (using a browser to format the HTML data). Given an HTML data source, we would like to find a way to create an underlying data structure that is type-safe and well formulated. We are motivated to study these problems for a variety of reasons. Firstly, for the purpose of conducting empirical studies, entering the data into the computer by hand is both error-prone and tedious. We seek a means to obtain this data, using free data feeds, so that we can build dynamically-updated displays and perform data mining functions. Secondly, we find that easy to parse data enables us to teach our students the basic concepts of data mining using a simple first example. This example is used in a first course on network programming. Finding the data, on-line, and free, is a necessary first step toward this type of data mining. Quotes have been available for years, from Yahoo. We can obtain the quotes, using comma-separated values (CSV) by constructing a URL and entering it into a browser. For example: