java.io package contains classes that perform input and output. In Java, I/O classes are differentiated according to
the type of data being read or written. Byte oriented and numeric data is written with output streams
and read with input streams. Character data, that is text, is written with
writers and read with readers. Readers and writers operate much like streams
but understand how to convert to and from various external character sets like Big-5 Chinese or MacRoman into Unicode. Whether you use streams or readers
and writers depends on the type of data you're dealing with. In Java 1.1
and later all text data, especially non-ASCII text, should be passed through a reader or writer.
The two main stream classes are java.io.InputStream and java.io.OutputStream. The two main reader and writer classes
are java.io.Reader and java.io.Writer
These are abstract base classes for many different subclasses with more specialized abilities.