Please help with reading fixed-length file

Question

I am reading a fixed-length file from a batch program and I need to read through each line, parsing out records in each, and replacing the first character in each line after I finish processing. I am using a RandomAccessFile, but I am not sure if this is best for my needs.
Here is essentially the code that I am using:
RandomAccessFile raf = new RandomAccessFile(File, "rw");
int pointer = 0;
int recordLength = 65;
int counter = 0;
string test = "X";
pointer = raf.getFilePointer();
while ((line = raf.readLine()) != null) {
//set file pointer
seek(counter * recordLength);
counter ++;
if (line.substring(0, 1).equals(test)) {
continue;
var1 = line.substring(7, 22);
var2 = line.substring(23, 41);
var3 = line.substring(42, 52);
var4 = line.substring(53, 53);
//PROCESSING
raf.writeChar(test);

Answer 1

Thanks for the suggestion. I think that the
BufferedReader is the way that I will go. Do you
happen to know the best way to update the 1st Char of
each line as I'm reading each line using Buffered
Writer?Hi,
To update the first char of each line, you could read each line of the file into a StringBuffer, modify the value, and then write the value back out to the file.
I had to do something similar.
eg.
StringBuffer buf = new StringBuffer();
BufferedReader in = new BufferedReader(
    // data file source
new FileReader(db_location));
String s;
// while there are still items to read
while ((s = in.readLine()) != null)
    System.out.println("reading file");
    // split into component parts so we can modify
    StringTokenizer t = new StringTokenizer(s,",");
    int id = Integer.parseInt(t.nextToken());
    String code = t.nextToken();
    int quantity = Integer.parseInt(t.nextToken());
    // copy component parts into StringBuffer
    buf.append(id+",");
    buf.append(code+",");
    buf.append("\n");
     // use StringBuffer methods here to isolate first character
     // use StringBuffer methods to replace first value of input in buffer
     // eg.
          buf.replace(index,length,","+ new_code);
// print out the StringBuffer to rewrite updated file
PrintWriter output = new PrintWriter(
    new BufferedWriter(
    new FileWriter(db_location, false)));
output.println(buf.toString());
output.close();As always, there is more than one way to skin a cat. But this is my way.
I think that JDK 1.4 has some new methods, but not 100% sure of that.
//Daniel.