About Programming

Why Is Computer Programming Important:

The Early Days of Programming

During the early 1980s, Chris worked for a computer software firm. The firm wrote code for word processing machines. (At the time, if you wanted to compose documents without a typewriter, you bought a “computer” that did nothing but word processing.) Chris complained about being asked to write the same old code over and over again. “First, I write a search-and-replace program. Then I write a spell checker. Then I write another search-and-replace program. Then, a different kind of spell checker. And then, a better search-and-replace.”

How did Chris manage to stay interested in his work? And how did Chris’s employer manage to stay in business? Every few months, Chris had to reinvent the wheel. Toss out the old search-and-replace program, and write a new program from scratch. That’s inefficient. What’s worse, it’s boring.

For years, computer professionals were seeking the Holy Grail — a way to write software so that it’s easy to reuse. Don’t write and rewrite your search-and replace code. Just break the task into tiny pieces. One piece searches for a single character, another piece looks for blank spaces, a third piece substitutes one letter for another. When you have all the pieces, just assemble these pieces to form a search-and-replace program. Later on, when you think of a new feature for your word processing software, you reassemble the pieces in a slightly different way. It’s sensible, it’s cost efficient, and it’s much more fun.

The late 1980s saw several advances in software development, and by the early 1990s, many large programming projects were being written from prefab components. Java came along in 1995, so it was natural for the language’s founders to create a library of reusable code. The library included about 250 programs, including code for dealing with disk files, code for creating windows, and code for passing information over the Internet. Since 1995, this library has grown to include more than 3,000 programs. This library is called the API — the Application Programming Interface.

Every Java program, even the simplest one, calls on code in the Java API.  This Java API is both useful and formidable. It’s useful because of all the things you can do with the API’s programs. It’s formidable because the API is so extensive. No one memorizes all the features made available by the Java API. Programmers remember the features that they use often, and look up the features that they need in a pinch. They look up these features in an online document called the API Specification (known affectionately to most Java programmers as the API documentation, or the Javadocs).

The API documentation describes the thousands of features in the Java API.  As a Java programmer, you consult this API documentation on a daily basis. You can bookmark the documentation at the Sun Microsystems Web site and revisit the site whenever you need to look up something. But in the long run (and in the not-so-long run), you can save time by downloading your own copy of the API docs.