Question

I ran into a weird problem, and i was wondering if anyone has an idea what could be the cause. I’m reading in a file ( a small exe of 472 KB ) with FileInputStream, i plan to send the file torugh RMI connection, and i had an idea, where i could show the upload’s % based on how much have i already sent trough compared to the overall length of the file.

First i tried it out locally and i couldn’t get it work. Here is an example, what i was doing.

FileInputStream fileData = new FileInputStream(file);
reads = new ArrayList<Integer>();
buffers = new ArrayList<byte[]>();
int i = 0;
while ( (read = fileData.read(buffer)) > 0) {
      System.out.println("Run : " + (i + 1));
      outstreamA.write(buffer, 0, read);
      reads.add(read);
      buffers.add(buffer);
      outstreamB.write(this.buffers.get(i), 0, this.reads.get(i));
      i = i + 1;
}

This two FileOutputStream creates two files ( same ones just with different name ), works fine. However, when i’m not using fileData.read() but any other for / while, it just dosen’t work. It creates the exact same file ( length is exactly the same ) but my Window cannot run the exe, i get an error message :
“The version of this file is not compatible with the version of Windows you’re running…”.

This is how i tried:

//for (int i = 0; i < buffers.size(); ++i) {
  i = 0;
//while ( (read = fileData2.read(buffer)) > 0) {
  while ( i < size) {
      System.out.println("Run#2 : " + (i + 1));
      outstreamC.write(this.buffers.get(i), 0, this.reads.get(i));
      i = i + 1;
  }

fileData2 is the same as fileData. If i work with fileData2.read(buffer), outstreamC creates a working file aswell.

It dosen’t matter if i run with for till the list’s size, or till “size” which equals the time i entered the first while. There is something missing, and i cannot figure it out.

The weird thing is, outstreamB creates a working file, yet outstreamC cannot, but they working with the exact same items.

Originally i was planning to pass the “read” and “buffer” each time i entered the first while trough RMI connection, and put everything together on the other side, after all the parts arrived, but now my plan is kinda dead. Anyone has maybe an idea, how could i solve this, or achieve something similar to be able to send files trough RMI?

Best regards,
Mihaly

Answer 1

Your code can never work. You are reading into the same buffer repeatedly and adding the same buffer to a list. So the list contains several copies of the final data you read. You would need to allocate a new buffer every time around the loop.