title: How do I let a user upload files to internal storage?
body: <p>I am writing a small app that reads files that must be regularly written to storage on the device from a source external to the device, be it USB, Bluetooth, Airdroid, etc. From what I've read, nothing like that can write to internal storage. I would like to manage the files in internal storage for access privacy.</p>
  
  <p>My first solution is an activity that lets the user write files to external storage, and then tap a button to transfer them to internal storage. If this doesn't happen in n minutes, the files on external storage are destroyed. But, I a have since found out that <code>getExternalStorageDirectory</code> is pretty useless, because devices emulate external storage on internal storage, and Android can't know if and how this is done.</p>
  
  <p>Yet I was wondering if there wasn't some sort of built-in activity that lets users upload or download files directly from internal storage, but without free access to the whole file structure of internal storage, like they have with internal storage.</p>
  
  <p>As a last resort, maybe my app can receive the files over a TCP connection and write them to internal storage itself. It's messy, but so is trying to find an SD card. See the question <a href="http://Find%20an%20external%20SD%20card%20location">Find an external SD card location</a>.</p>
  
  <p><strong>NEW:</strong> The aim of this exercise is to find all .csv files in a directory on the SD card, let the user choose one, process it, and write an output file to the SD card. The user will enter a "Weight" value that will be used in the calculations for processing the file. </p>
  
  <p>But, since Android is so unreliable at providing the location of really external storage, i.e. the SD card, I want to try and store the files in internal storage, where Android seems to be more honest and reliable about the location of that storage.</p>