title: Save image/video file to app's internal storage in subfolder
body: <p>I know similar questions like that have been asked a lot here already but I just can't find an answer that works for me.</p>
  
  <p>I have a File object which has a path pointing to the SD card (external storage). For example: </p>
  
  <pre><code> File selectedFile = new File("/storage/emulated/0/Pictures/Screenshots/Screenshot_20160725-185624.png");
  </code></pre>
  
  <p>What I want to do now is to save that image/video to a subfolder of my app's internal storage.</p>
  
  <p>For example, saving the File to here:
  INTERNAL_STORAGE/20/public_gallery/300.png</p>
  
  <p>The problem I have is when I'm using</p>
  
  <pre><code>outputStream = context.openFileOutput("20/public_gallery/300.png", Context.MODE_PRIVATE);
  ...
  outputStream.write(content.getBytes());
  ...
  </code></pre>
  
  <p>I can't use any "/" for a subfolder.</p>
  
  <p>If anyone could provide me a small code example I would be extremely grateful.</p>