java.lang.IllegalArgumentException: The observer is null

Question

A user of one of my apps reported this error. I\'m confused as to what it means an how to fix it. After a bit of googling...still no luck. Anyone seen this before or know how

Answer 1

I too was having the same problem and it seems that unregisterDataSetObserver on your DealPageAdapter is being called twice. To fix the problem I overwrote the unregisterDataSetObserver in my Adapter as such

@Override
public void unregisterDataSetObserver(DataSetObserver observer) {
    if (observer != null) {
        super.unregisterDataSetObserver(observer);
    }
}

Hope this helps!

Answer 2

An alternative solution is to wrap the ListView and catch the exception. This solution worked for me, and I have yet not found any side effects.

    public class CustumListView extends ListView {


  public CustumListView(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  @Override
  protected void onDetachedFromWindow() {
    try {
      super.onDetachedFromWindow();
    } catch(IllegalArgumentException iae) {

    }
  }
}

Answer 3

There are a few people who have had your problem Here and Here

From looking at the call stack it looks like your "view" registered a observer that it's now trying to unregister. That observer is no longer there even though it's expected. Hence the error. This might be a bug or it might be related to how you're doing things.

Trying looking through the Android Source to see if you can track it down.

Good luck.