Input Stream Classes

They provide byte-by-byte data.
Their names usually tell you what they do.
The most important methods are:
- abstract int read(): reads a single byte, an array, or a subarray of bytes. It returns the bytes read, the number of bytes read, or -1 if end-of-file has been reached.
- read(): takes the byte array, reads an array or a subarray of bytes and returns a -1 if the end-of-file has been reached.
- skip(): takes long, skips a specified number of bytes of input and returns the number of bytes actually skipped.
- available(): returns the number of bytes that can be read without blocking. Both the input and output can block threads until the byte is read or written.
- close(): closes the input stream to free up system resources.