java.io help

[Pojahn_M]

I am looking for classes in java.io that can read a line(and store that line in a string) from a binary file(example a avi video, png image or exectuable file), and then write this line to a file, without loosing the binary format.
So if I did like this:

		//Objects

		String s = in.readLine ();
		while (s != null)
		{
			out.write (s);
			out.newLine ();
			s = in.readLine ();
		}
		in.close ();
		out.close ();

If the input file was, example somemovie.avi, the output file would be an exact copy, and playable in media players like the orginal was.
I tried myself some stuff:

		File fil = new File ("C:\\img.png");
		FileInputStream fis = new FileInputStream (fil);
		InputStreamReader fin = new InputStreamReader (fis);
		BufferedReader in = new BufferedReader (fin);

		File fol = new File ("C:\\imgout.png");
		FileOutputStream fo = new FileOutputStream (fol);
		DataOutputStream out = new DataOutputStream (fo);

these did not work. The binary format was lost, and my test image was corrupted.

What classes should I use?

[JosAH]

Don't use Readers for that; they are character based streams and they convert bytes to characters according to an decoding scheme; that's why your output isn't the same as your input. Use InputStreams instead; they simply read bytes and don't play tricks on them. For binary files 'lines' don't have any meaning; you have to read 'blocks' of bytes and process them (such as writing them with OutputStream objects).

kind regards,

Jos

[Pojahn_M]

InputStream and OutputStream are abstract classes, so which ones if its sub classes should I use?
FileInputStream may work for reading, and FileOutputStream for output?

[JosAH]

InputStream and OutputStream are abstract classes, so which ones if its sub classes should I use?
FileInputStream may work for reading, and FileOutputStream for output?

Learn how to read the API documentation; it mentions in one of its headers near the top 'Direct Known Subclasses'; that section lists the subclasses of the InputStream class (for your particular example). Those are links; you can click on them and see their API page. And yes, a FileInputStream and FileOutputStream are what you need. You can even wrap them in buffered streams if you want.

kind regards,

Jos