Creating zip archive in Java

Question

I have one file created by 7zip program. I used deflate method to compress it. Now I want to create the same archive (with the same MD5sum) in java. When I create zip file, I used the algorithm that I found on the Internet for example http://www.kodejava.org/examples/119.html but when I created zip file with this method the compressed size is higher than size of the uncompressed file so what is going on? This isn't a very useful compression. So how I can create zip file that is exactly same as zip file that I created with 7zip program ? If it helps I have all information about zip file that I created in 7zip program.

Answer 1

// simplified code for zip creation in java  import java.io.*; import java.util.zip.*;  public class ZipCreateExample {      public static void main(String[] args) throws Exception {          // input file          FileInputStream in = new FileInputStream("F:/sometxt.txt");          // out put file          ZipOutputStream out = new ZipOutputStream(new FileOutputStream("F:/tmp.zip"));          // name the file inside the zip  file          out.putNextEntry(new ZipEntry("zippedjava.txt"));           // buffer size         byte[] b = new byte[1024];         int count;          while ((count = in.read(b)) > 0) {             out.write(b, 0, count);         }         out.close();         in.close();     } }