Reads characters into a portion of an array. This method will block until some input is available, an I/O error occurs, or the end of the stream is reached.

Parameters:

cbuf		Destination buffer
off		Offset at which to start storing characters
len		Maximum number of characters to read

Returns:  The number of characters read, or -1 if the end of the stream has been reached

Exceptions:

IOException

If an I/O error occurs