How to speed up unzipping time in Java / Android?

Thanks for the solution Robert. I modified my unzip method and now it takes only a few seconds instead of 2 minutes. Maybe someone's interested in my solution. So here you go:

public void unzip() {

    try {
        FileInputStream inputStream = new FileInputStream(filePath);
        ZipInputStream zipStream = new ZipInputStream(inputStream);
        ZipEntry zEntry = null;
        while ((zEntry = zipStream.getNextEntry()) != null) {
            Log.d("Unzip", "Unzipping " + zEntry.getName() + " at "
                    + destination);

            if (zEntry.isDirectory()) {
                hanldeDirectory(zEntry.getName());
            } else {
                FileOutputStream fout = new FileOutputStream(
                        this.destination + "/" + zEntry.getName());
                BufferedOutputStream bufout = new BufferedOutputStream(fout);
                byte[] buffer = new byte[1024];
                int read = 0;
                while ((read = zipStream.read(buffer)) != -1) {
                    bufout.write(buffer, 0, read);
                }

                zipStream.closeEntry();
                bufout.close();
                fout.close();
            }
        }
        zipStream.close();
        Log.d("Unzip", "Unzipping complete. path :  " + destination);
    } catch (Exception e) {
        Log.d("Unzip", "Unzipping failed");
        e.printStackTrace();
    }

}

public void hanldeDirectory(String dir) {
        File f = new File(this.destination + dir);
        if (!f.isDirectory()) {
            f.mkdirs();
        }
}

I don't know if unzipping on Android is slow, but copying byte for byte in a loop is surely slowing it down even more. Try using BufferedInputStream and BufferedOutputStream - it might be a bit more complicated, but in my experience it is worth it in the end.

BufferedInputStream in = new BufferedInputStream(zin);
BufferedOutputStream out = new BufferedOutputStream(fout);

And then you can write with something like that:

byte b[] = new byte[1024];
int n;
while ((n = in.read(b,0,1024)) >= 0) {
  out.write(b,0,n);
}