🚀 go-pugleaf

Hi all,

I have data as follows in a file

 10000     Ams3vh45  02/01/1980 00:20    78-D-175677    Matthew             Murray              Ranelagh                      0
 10010     Onm6io99  05/01/1980 05:57    76-D-712944    Oonagh              Moran               Ballymon                      0
 10020     Nny5ev37  08/01/1980 11:35    76-D-837556    Claire              Leinster            Ranelagh                      0


127 (+ carriage return) = 128 characters wide.


Now, what I want to do is to change the zero at the end of (say) the
second line into a 1.

So I tried this 


  public static void deleteRecordAtLine(int theLineNumber (= 2 in this case)) throws IOException
  {

    System.out.println("\nThe record being deleted is line number " + theLineNumber);

    File myMainDataFile = new File("mainfile.dat");

    RandomAccessFile mainDataFile = new RandomAccessFile(myMainDataFile, "rw");

    mainDataFile.seek(theLineNumber * 128);
    String recordToBeMarkedDeleted = mainDataFile.readLine();

    StringBuffer strBuffer = new StringBuffer(recordToBeMarkedDeleted);

    strBuffer.insert(125,'1');

    recordToBeMarkedDeleted = strBuffer.toString();

    mainDataFile.seek(theLineNumber * 128);

    mainDataFile.writeChars(recordToBeMarkedDeleted);

    mainDataFile.close();

  }


But this just makes that line and the one beneath it into gibberish.

I am new to all this stuff about Strings, StringBuffers, arrays of
bytes, characters &c.

Anybody know any good references on this kind of thing and also could
anyone point out the flaw(s) in my code?

BTW, this is not the only thing I have tried.


Paul...