ListViewに関するべからず集

Google I/O 2010より
http://www.youtube.com/watch?v=wDBM6wVEO70

-









Don't
android:layout_height="wrap_content" (ListViewでwrap_contentを使うな)

Listview is virtualized, remember?
wrap_content = "as big as my children"
  -- ListViewsupports unevenly sized children
  -- Measured only 3 children(最初の３つしか見ない)
  -- Still expensive
 Wrong result (結果を間違える)




















-









Don't
ListView inside a ScrollView (ScrollViewとListViewを一緒に使うな)
ScrollView scrolls
ListView scrolls
 who will scroll?



















-









Don't
Cache views in the adapter(Adapter内でViewをキャッシュするな)

Don't outsmart ListView
 - ListView assumes ownership of views

Complex recycling mechanism
 - Numerous optimizations
 - Sometimes we even leave bugs there

Undead views is the worst case
 - View both in the recycler and on screen




















-









Don't
Use a ListView when you don't need one! (必要なときにだけ使え)

ListView
 - is for repeating, unbounded data
 - Adds (lots of) complexity

Will a LinearLayout or ScrollView do the job?






-


おまけ
getView内でのinfrate(resource,root, attachToRoot)のattachToRootは常にfalseにせよ