Types of Streams

A stream object may be:

• An input stream or an output stream,
• a processing stream or an ordinary stream,
• a character-oriented stream or a byte-oriented stream,
• and may be connected to a variety of sources or destinations.

There are many types of streams. For example, a stream might be an "input, character-oriented, processing stream". Another stream might be an "byte-oriented output stream". Not only are there many types of streams, there are many ways to connect them together. The IO aspects of a program may take as much work as all the rest of the program!

This situation is common to all production (industrial strength) programming languages. IO is a big topic because of the wide variety of IO devices and the wide variety of data formats. A production language must be able to read data from sources written by any language running on any type of computer. For example, a program might need to read data from magnetic tapes written 30 years ago by a COBOL program running on an IBM mainframe. (You would likely use byte-oriented streams for this).

The good news is that the data formats that Java uses are the same for all computers. If a Java program running on a Macintosh writes a text file, that file can easily be read by a Java program running on a PC or on any other computer.

This is not true of most other languages. A "C" program running on one type of computer is unlikely to create a file that can easily be read by a "C" program running on another type of computer. Worse than that, two different "C" compilers for the same computer are free to use different data formats!