StackOverflow2013

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PO
primarykey
Id
13095406
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2012-10-26T22:43:14.663
FavoriteCount
0
LastActivityDate
2012-10-26T22:51:53.277
LastEditDate
2012-10-26T22:51:53.277
LastEditorUserId
1559625
OwnerUserId
1559625
ParentId
13083597
PostTypeId
2
Score
0
ViewCount
0
LastEditorDisplayName
text
Body
I give it a try with synchronization again. Either synchronize the fetchDrawableOnThread(), or synchronize the global hashmap data within fetchDrawableOnThread(). First i thought the issue is gone, but when i tried more times later, i found the issue is still there. Then i thought about the synchronization. fetchDrawableOnThread() is called from getView(), and getview() itself does not have a concurrency issue. Even if as Yogesh said, what happened INSIDE getView() is thread-based, and return early or late, it can not affect the correctness of getView(), i.e. the list item's display, only the sooner or later. What i did(synchronization) inside fetchDrawableOnThread() i think it's still correct, 'cause i used a hashmap to cache images downloaded from remote url, and this hashmap is read/write upon in a multi-thread situation, so it should be locked. But i do not think it's the rootcause of the UI misplace, if hashmap is messed up, the image misplacement will be permanent. Then i looked further on convertView reuse mechanism based on Praful's explanation. He explained clearly what happened when image always comes from remote and no cache locally, but my situation is i waited my list to display fully, i.e. all images download complete and cached complete, before i do the fast scroll. So in my experiment, the images are read from cache. Then when inspecting my code, i saw one minor difference in the use of convertView as in getView() method, a lot of the example usages are like this: <pre><code>public View getView(int position, View convertView, ViewGroup parent) { // case 1 View v = convertView; .... // modify v return v; } </code></pre> However the example i happened to copy from use: <pre><code>public View getView(int position, View convertView, ViewGroup parent) { // case 2 .... // modify convertView return convertView; } </code></pre> I thought it makes no difference at first, 'cause according to what android says, 'ListView sends the Adapter an old view that it's not used any more in the convertView param.', so why not use 'convertView' para directly? But i guess i was wrong. I changed my getView() code to case 1. Boom! everything works. No funny business ever no matter how fast i scroll the list. Quite strange, is convertView only old, or is it old & in-use? If the later, we should only get a copy and then modify..... ??
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1. This table or related slice is empty.
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1. POIssue when fast scroll a listview?
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PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USuser1559625
UserOwnerUserId
1. USuser1559625
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