ListView与自定义ListDataAdapter请求项两次 [英] ListView with custom ListDataAdapter requests items twice
问题描述
我已经通过创建一个派生自VirtualizedDataSource的类来实现IListDataAdapter，但是当ListView使用它时我看到了一些奇怪的行为。
I've implemented IListDataAdapter by creating a class derived from VirtualizedDataSource, but I'm seeing some odd behaviour when it's used by the ListView.
向右滑动时， ; itemsFromIndex按预期重复调用以在数据中进行分页。当我一直向右滑动时，它会从一开始就再次请求所有项目！我可以缓存项目以保存再次获取它们，但是有一些
的方法来改变ListView的行为，所以它不会两次请求项目吗？如果我再次开始向左滚动，我会理解是否请求了这些项目，但我不了解当前的行为。
When swiping right, itemsFromIndex is called repeatedly as expected to page in the data. When I swipe all the way to the right, it then requests all the items again from the start! I could cache the items to save fetching them again, but is there some way to change the behaviour of the ListView so it doesn't request the items twice? I would understand if it requested the items if I started scrolling left again, but I don't understand the current behaviour.
推荐答案
当然，如果您有大量数据，这才真正重要吗？ 对于少量数据，这是微不足道的。 默认情况下，一旦Listview达到项目阈值，它就会开始以预定义的数据页面大小获取数据。 您可以通过
更好地控制获取的内容以及何时需要。 我实际上刚刚回答了一个与listview如何逐步获取数据有关的问题：
Of course this would only really matter if you had a lot of data correct? For small amounts of data this is trivial. By default once Listview hits a threshold of items it would start fetching data in a pre-defined data page size. You can have a finer control of what gets fetched and when if you would like. I actually just answered a question related to how listview fetches data incrementally here:
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