title: Android out of memory prevention
body: <p>I have a list that shows thumbnails (small images) downloaded on the fly from the web.
  At some point, the process runs out of memory.
  How can I tell that the free memory is about to run off, so I can stop downloading more images?</p>
  
  <p>I would like to know it in advance in order not to be on the edge of out of memory.</p>
  
  <p>Note:
  It is not a memory leak, just lots of downloaded bitmaps.</p>
  
  <p>Thanks.</p>