Reading a field in a Binary file

[Denise Advincula]

Can we get a field in a binary file without reading the whole line..? For example, I have a binary file, and one "line" or record have 10 integers on it..

In my code I use this:

          
            FileInputStream file_in = new FileInputStream (myfile);
            DataInputStream in    = new DataInputStream (file_in);

            int [] line = new int[10]; // one "line" would have 0-9 as indices

            while (true) {
              try {
                  int data = in.readInt();
                  // assign the data read to line[dataindex%10]
                  // use % operation to make sure that the index will always be from 0-9
                  line[dataindex%10] = data;                   
                  if (((dataindex)%10) == 0) { // determines that this is the end of one "line" or record
                     // do processing stuffs here..
                  }

              }
              // break if end of binary file reached
              catch (EOFException eof) {
                 break;
              }
              dataindex++; // just add one to proceed to next index
            } // end while

This probably is not a good implementation of reading lines/records from a binary file. Because I only want the data in line[2] to be processed but I am still reading the other data... Is there a way to get the line[2] (data in index 2) directly without reading the whole binary file line/record?

I think these methods from the api are the answer but I'm not sure (and I don't want to create more arrays hopefully):

int read(byte[] b)
Reads some number of bytes from the contained input stream and stores them into the buffer array b.
int read(byte[] b, int off, int len)
Reads up to len bytes of data from the contained input stream into an array of bytes.

Hope you can shed me some light here. Thanks!!!

[Ulf Dittmer]

No, those methods don't allow you to skip over data.

If you can calculate exactly the byte location within the file, then you can use the RandomAccessFile class.

[Denise Advincula]

Ulf Dittmer wrote:No, those methods don't allow you to skip over data.

If you can calculate exactly the byte location within the file, then you can use the RandomAccessFile class.

Thanks! I used RandomAccessFile now, but I encountered some problems here. I hope you can help me again... Thank you!

[Rob Spoor]

Replied to that thread with the correct answer.