title: ListView getChildAt returning null for visible children
body: <p>I'm getting some strange behavior from a listview/the getChildAt method. </p>
  
  <p>I have a HashSet, iconsToUpdate, of icons that have been changed in the database. I want to iterate over the visible rows to see if any of their icons need to be updated to reflect the new icons. I don't need to test the icons not currently in view as they will be drawn properly when rendered.</p>
  
  <p>My problem is that getChildAt is returning null when it seems like it shouldn't. I know that getChildAt can only return views that are currently visible, but it is returning null for some of the visible rows.</p>
  
  <p>Here is my code that iterates over the visible rows:</p>
  
  <pre><code>Logger.debug("First visible index: " + f_listView.getFirstVisiblePosition());
  Logger.debug("Last visible index: " + f_listView.getLastVisiblePosition());
  for (int i = f_listView.getFirstVisiblePosition(); i &lt;= f_listView.getLastVisiblePosition(); i++) {
      String tag = "asdf"; // Remove when bug is fixed.
      if (f_listView == null) {
          Logger.debug("f_listView is null");
      } else if (f_listView.getChildAt(i) == null) {
          Logger.debug("Child at index " + i + " is null");
      } else {
          tag = (String) f_listView.getChildAt(i).getTag();
          Logger.debug("Successful at index " + i + ", tag is: " + tag);
      }
      if (iconsToUpdate.contains(tag)) {
          setIcon(i, f_aim.getInHouseIcon(tag));
      }
  }
  </code></pre>
  
  <p>Here is the log corresponding to a run of this loop:</p>
  
  <pre><code>D/...: First visible index: 3
  D/...: Last visible index: 8
  D/...: Successful at index 3, tag is: ...
  D/...: Successful at index 4, tag is: ...
  D/...: Successful at index 5, tag is: ...
  D/...: Child at index 6 is null
  D/...: Child at index 7 is null
  D/...: Child at index 8 is null
  </code></pre>
  
  <p>It should be noted that the first and last visible indexes are being correctly reported, as I am viewing rows 3-8 when I run this. Rows 6, 7, 8 are being rendered properly. How are they being displayed if they are null?</p>
  
  <p>Also, I do not know if this is important, but row 5 is the last visible row when I am at the top of the listview.</p>
  
  <p>Any info as to why these rows are being returned as null would be greatly appreciated.</p>
  
  <p>Thanks!</p>