code: public static void decompress(File source, File target) throws IOException {
          ZipInputStream zipIn = new ZipInputStream(new BufferedInputStream(new FileInputStream(source), BUFFER));
          BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(target));
          zipIn.getNextEntry();
          byte data[] = new byte[BUFFER];
  
          int count = 0;
          while ((count = zipIn.read(data, 0, BUFFER)) != -1) {
              bos.write(data, 0, count);
          }
          bos.close();
          zipIn.close();
      }
docs: Decompresses a zip file (source) that has a single zip entry.
  
  @param source
  @param target
  @throws IOException