Question

We shouldn’t use byte Stream as Sun Doc says –

actually it represents a kind of low-level I/O that you should avoid.

What is actually low-level I/O and what is exact problem using byte stream.

Answer 1

So the Java docs say:

CopyBytes seems like a normal program, but it actually represents a
kind of low-level I/O that you should avoid. Since xanadu.txt contains
character data, the best approach is to use character streams, as
discussed in the next section. There are also streams for more
complicated data types. Byte streams should only be used for the most
primitive I/O.

The byte streams give you access to the file as it is. Just the bytes. No interpration of any kind. That means no character set conversion, no handling of ints or floats in binary or ascii representation, no dealing with byte orders, or any of that. The higher level streams provide some of these.

Of course a program that copies a file is actually a pretty good example of something that needs a raw byte stream, because it doesn’t need or want to do any kind of intepretation of the data; it just wants to copy it verbatim.

So what the really mean is, use byte streams if you think you need them, but be sure you know what you are doing 🙂