Thread: Blackberry Api: Writing an array of bytes to a file

I am trying to read and write metadata to/from an mp3 file. I can read the data, but I cannot figure out how to write it.

I use the following code to get file access:

    FileConnection file = (FileConnection) Connector.open("file:///store/home/user/music/song.mp3");
    if(file.exists())
             java.io.InputStream inputStream = file.openInputStream();

Later, I read the data using the following code:

    buffer = new byte[length]; // length is predetermined earlier
    if (inputStream.read(buffer, 0, length) == length)
             String info = new String((buffer));

How do I write data (bytes) to the a designated location in the file? I am unsure of both the IO declarations and the specific code required to output my bytes.

Thank you in advance,

Julia

PS: I'm really new to this, I would really appreciate detailed answers. Thank you!

What classes and packages do you have for writing to files?
Are they similiar to the Java API classes and packages?

The two classes that I know of are OutputStream and InputStream.

I found this website that contains code to write data (bytes) to a new file. But I need to stick my data in the middle of a file, or at least at the very beginning/end. Is this possible?

Thank you!

need to stick my data in the middle of a file, or at least at the very beginning/end.

Think of a file as a string of words typed on a piece of paper. To add words at the beginning, means that all the words that were at the beginning have to be moved over to the right. The same when inserting in the middle.

Bottom line - everything from your insert point to the end of the file must be rewritten.

To insert in beginning/middle:
If I understand you correctly, I will need to create a separate class that will read in the data and then re-write everything past the point where I inserted data? And there is no internal class that does that already.

To insert at the end:
Is there an easy way to append byte data to the end of a file?

Thanks again!

append byte data to the end of a file

Some class constructors take a boolean flag to specify that data is to be appended.

I will need to create a separate class that will read in the data and then re-write everything past the point

Something like that. Some code some where has to read and rewrite the data that is being overwritten by the insert.