Hello @kartik,
This is my unzip method, which I use:
private boolean unpackZip(String path, String zipname)
{       
     InputStream is;
     ZipInputStream zis;
     try 
     {
         is = new FileInputStream(path + zipname);
         zis = new ZipInputStream(new BufferedInputStream(is));          
         ZipEntry ze;
         while((ze = zis.getNextEntry()) != null) 
         {
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             byte[] buffer = new byte[1024];
             int count;
             String filename = ze.getName();
             FileOutputStream fout = new FileOutputStream(path + filename);
             // reading and writing
             while((count = zis.read(buffer)) != -1) 
             {
                 baos.write(buffer, 0, count);
                 byte[] bytes = baos.toByteArray();
                 fout.write(bytes);             
                 baos.reset();
             }
             fout.close();               
             zis.closeEntry();
         }
         zis.close();
     } 
     catch(IOException e)
     {
         e.printStackTrace();
       return false;
     }
    return true;
}
Hope this work!!