Download the multiple files/documents from Internet to android device storage

//here we are checking the directory already exists or not



File directory = new File("file directory name/full path");
        if(!directory.exists()){
            directory.mkdirs();
        }

//for loop to download the multiple files.
    for(int i=0; i<presentationsList.size();i++){
             
           File file=new File(directory, filename);
//here we checking the if file already exists or not. and even if the file size is zero we delete the file and recreate the file.
          if(file.exists() && file.length()==0){
              file.delete();
          }
   
//here is the actual stuff to download the file.

           if(!file.exists()){
             
               try
               {
        URLConnection ucon = new URL(proved the url here).openConnection();
                    InputStream is = ucon.getInputStream();
                     fsize=ucon.getContentLength();
               
                    
                BufferedInputStream bis = new BufferedInputStream(is);
               ByteArrayBuffer baf = new ByteArrayBuffer(ucon.getContentLength());
                    int current = 0;
                    while ((current = bis.read()) != -1) {
                        baf.append((byte) current);
                    }
                   
                    FileOutputStream fos = new FileOutputStream(file);
                    fos.write(baf.toByteArray());
                    fos.flush();
                    fos.close();

               //if the downloaded file size is less than the actual file size then we remove the file
                   if(file.length()<fsize){       
                         if(file.exists())
                             file.delete();
                     }                   
               }
               catch (Exception e)
               {
                   if(file.length()<fsize){       
                        if(file.exists())
                            file.delete();
                    }    
                   e.printStackTrace();
               }
             }
             }