InputStream
InputStream is an abstract class from which all
byte-oriented input streams are derived.
Its descendant classes are used for general-purpose input
(non-character input).
These streams are aimed at
delivering data to a program in groups of 8-bit bytes.
The bytes can be grouped into the size necessary for
the type of data.
For example,
if a disk file contains 32-bit int data,
data can be delivered to the program in 4-byte groups
in the same format as Java primitive type int.
We will be mostly concerned with DataInputStream
and FileInputStream.
