Getting Down to Business
At this point in your travels, you might be getting the impression that Java is primarily of use to science fiction buffs and people who have body parts to show the world. Although those two subject areas are enough to keep many of us entertained for days, the next stop on our trip shows an example of Java getting down to business.
Direct your web browser to http://www.alphatrade.com/partners-freetools.php.
This example shows several financial tools presented as Java programs: a scrolling ticker for current prices on up to 20 stocks, a U.S. and Canadian index chart that can be customized, and a "snap quote" price report. Figure 3.5 shows these three programs running.
Figure 3.5 Java programs from AlphaTrade.com that are used to analyze stock market prices and overall indices.
Unlike other stock analysis programs that require the installation of software on the computers of each employee who needs access, the use of Java enables AlphaTrade.com to make the programs available to anyone with a web browser—all the employees would have to do is access the company’s website.
A program such as AlphaTrade.com’s stock ticker applet can be thought of in several different ways. One way is to think of a program as an object—something that exists in the world, takes up space, and has certain things it can do. Java, like the C++ language, uses object-oriented programming, as you will see during Hour 10, "Creating Your First Object." Object-oriented programming (OOP) is a way of thinking about computer programs. A program is thought of as a group of objects. Each object handles a specific task and knows how to speak to other objects. For example, a word processing program could be set up as the following group of objects:
A document object, which is the area where you type in text
A spell-checking object, which can look over the document object to find any possible spelling errors
A printer object, which handles the printing of the document
A menu object, a mouse object, and many others
The word processing software is a collection of all the objects necessary to get work done.
OOP is a powerful way to create programs, and it makes the programs you write more useful. Consider the word processing software. If the programmer wants to use the spell-checking capabilities of that program with some other software, the spell-checking object is ready for use with the new program. No changes need to be made.