List unscrollable with custom Adapter #8

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1. egfconnor commented on Aug 28, 2013

   

   egfconnor

   on Aug 28, 2013

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   Setting a boolean so it runs once has fixed it, but I'm not sure what the side effects are:

   listView.getViewTreeObserver().addOnGlobalLayoutListener(
   new ViewTreeObserver.OnGlobalLayoutListener() {
   boolean haveRan = false;

                           @Override
                           public void onGlobalLayout() {
                               if (haveRan == false) {
                                   mQuickReturnHeight = quickReturnLayout
                                           .getHeight();
                                   listView.computeScrollY();
                                   haveRan = true;
                               }
                           }
                       });
   
2. bkhall commented on Sep 19, 2013

   

   bkhall

   on Sep 19, 2013

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   @egfconnor I think the issue relates to the fixed adapter size shown in the example. If you change the dataset (grow or shrink) in the adapter and then call notifyDataSetChanged on the adapter, an IndexOutOfBoundsException is thrown.

   This is caused by the way @LarsWerkman defined the mItemOffsetY array in the computeScrollY function. As currently defined, the mItemOffestY array is defined ONLY once and the size is based on the initial size of the dataset.

   To fix it so that it can accept changes in the dataset, change this line:

   if (mItemOffsetY == null)

   to

   if (mItemOffsetY == null || mItemOffsetY.length != mItemCount)

   That will allow the mItemOffsetY array to be redefined when the dataset changes and should allow it to work with custom adapters (especially cursoradapters and loaders).
3. egfconnor commented on Sep 19, 2013

   

   egfconnor

   on Sep 19, 2013

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   Thanks for the info @bkhall. I will try and test this soon as currently I have went away from using it completely. Will hopefully create a sample that isolates everything to a simple level.
4. LarsWerkman commented on Sep 24, 2013

   

   LarsWerkman

   on Sep 24, 2013

   Owner

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   Thanks @bkhall yeah you could do that I think!
5. Zordid commented on Mar 27, 2014

   

   Zordid

   on Mar 27, 2014

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   This is why I think this is not a good starting point in terms of breaking lots of conecpts crucial to ListViews and Adapters.
   First: it breaks when adapter's content changes. Normally this is all well designed, a call to notifyDataSetChanged from the adapter informs all observers (the list). But this approach breaks this.
   Second: in terms of efficiency it is a horrible mistake to call getView in a loop on ALL elements in the list. Never, ever, I repeat, never, ever, do this!
6. AlexeyFreelancer commented on May 29, 2014

   

   AlexeyFreelancer

   on May 29, 2014

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   @Zordid do you have another solution for implementation? Could you to share it?