What's the optimum buffer size?

Question

Hi everyone,
I'm having trouble with my unzipping method. The thing is when I unzip a smaller file, like something 200 kb, it unzips fine. But when it comes to large files, like something 10000 kb large, it doesn't unzip at all!
I'm guessing it has something to do with buffer size... or does it? Could someone please explain what is wrong?
Here's my code:
import java.io.*;
import java.util.zip.*;
  * Utility class with methods to zip/unzip and gzip/gunzip files.
public class ZipGzipper {
  public static final int BUF_SIZE = 8192;
  public static final int STATUS_OK          = 0;
  public static final int STATUS_OUT_FAIL    = 1; // No output stream.
  public static final int STATUS_ZIP_FAIL    = 2; // No zipped file
  public static final int STATUS_GZIP_FAIL   = 3; // No gzipped file
  public static final int STATUS_IN_FAIL     = 4; // No input stream.
  public static final int STATUS_UNZIP_FAIL  = 5; // No decompressed zip file
  public static final int STATUS_GUNZIP_FAIL = 6; // No decompressed gzip file
  private static String fMessages [] = {
    "Operation succeeded",
    "Failed to create output stream",
    "Failed to create zipped file",
    "Failed to create gzipped file",
    "Failed to open input stream",
    "Failed to decompress zip file",
    "Failed to decompress gzip file"
    *  Unzip the files from a zip archive into the given output directory.
    *  It is assumed the archive file ends in ".zip".
  public static int unzipFile (File file_input, File dir_output) {
    // Create a buffered zip stream to the archive file input.
    ZipInputStream zip_in_stream;
    try {
      FileInputStream in = new FileInputStream (file_input);
      BufferedInputStream source = new BufferedInputStream (in);
      zip_in_stream = new ZipInputStream (source);
    catch (IOException e) {
      return STATUS_IN_FAIL;
    // Need a buffer for reading from the input file.
    byte[] input_buffer = new byte[BUF_SIZE];
    int len = 0;
    // Loop through the entries in the ZIP archive and read
    // each compressed file.
    do {
      try {
        // Need to read the ZipEntry for each file in the archive
        ZipEntry zip_entry = zip_in_stream.getNextEntry ();
        if (zip_entry == null) break;
        // Use the ZipEntry name as that of the compressed file.
        File output_file = new File (dir_output, zip_entry.getName ());
        // Create a buffered output stream.
        FileOutputStream out = new FileOutputStream (output_file);
        BufferedOutputStream destination =
          new BufferedOutputStream (out, BUF_SIZE);
        // Reading from the zip input stream will decompress the data
        // which is then written to the output file.
        while ((len = zip_in_stream.read (input_buffer, 0, BUF_SIZE)) != -1)
          destination.write (input_buffer, 0, len);
        destination.flush (); // Insure all the data  is output
        out.close ();
      catch (IOException e) {
        return STATUS_GUNZIP_FAIL;
    } while (true);// Continue reading files from the archive
    try {
      zip_in_stream.close ();
    catch (IOException e) {}
    return STATUS_OK;
  } // unzipFile
} // ZipGzipperThanks!!!!

Answer 1

Any more hints on how to fix it? I've been fiddling
around with it for an hour..... and throwing more
exceptions. But I'm still no closer to debugging it!
ThanksDid you add:
e.printStackTrace();
to your catch blocks?
Didn't you in that case get an exception which says something similar to:
java.io.FileNotFoundException: C:\TEMP\test\com\blah\icon.gif (The system cannot find the path specified)
     at java.io.FileOutputStream.open(Native Method)
     at java.io.FileOutputStream.<init>(FileOutputStream.java:179)
     at java.io.FileOutputStream.<init>(FileOutputStream.java:131)
     at Test.unzipFile(Test.java:68)
     at Test.main(Test.java:10)Which says that the error is thrown here:
     // Create a buffered output stream.
     FileOutputStream out = new FileOutputStream(output_file);Kaj