android listview 选中状态,Android：在ListView打开时将项目设置为选中状态？

雨点打透心脏的1/2处 2022-10-05 03:52 196阅读 0赞

我正在使用适配器并且不想设置自定义背景颜色，但在drawable xml中使用android：state\_selected。 SetSelection对我不起作用，但也许这也是因为我需要SetNotifyDataChanged，这表明Selected State不是持久的。

我还发现ListView中项目的Selected状态不是持久的，因为SetNotifyDataChanged导致更新ListView布局，清除它们。 在适配器的GetView中将项目设置为Selected也太快了。

最后，在更改listview的布局之后，我为所选项的视图设置了Selected状态，这是在触发LayoutChange事件时(在Java中，它可能附加到ListView的OnLayoutChangeListener)。

为了使它变得非常简单，我将所选项目的视图存储为Adapter的SelectedItemView。 在ListView的LayoutChange事件处理程序中，我只是将适配器的SelectedItemView.Selected设置为true。

这是我的Activity中的代码，我为ListView设置了适配器，也订阅了LayoutChange(或者在Java中附加了一个OnLayoutChangeListener)

ringTonesListView.Adapter = ringTonesListAdapter; ringTonesListView.LayoutChange += (s, layoutChangeArgs) => \{ //At this stage the layout has been updated and the Selected can be set to true for the view of the selected item. This will result in android:state\_selected logic to be applied as desired and styling can be completely done per layout in Resources. ringTonesListAdapter.SelectedItemView.Selected = true; \};

这是我的适配器代码：

public class RingTonesListAdapter : BaseAdapter\{ ListItems \{ get; set; \} public override View GetView(int position, View convertView, ViewGroup parent) \{ View view = convertView; // re-use an existing view, if one is available // otherwise create a new one if (view == null) \{ view = Context.LayoutInflater.Inflate(Resource.Layout.AlertSoundItem, parent, false); view.Click += SelectRingTone; \} RingTone ringTone = this\[position\]; if (ringTone.Selected) \{ //==> Important //Store this view since it's the view for the Selected Item SelectedItemView = view; //Setting view.Selected to true here doesn't help either, since Selected will be cleared after. \} return view; \} private void SelectRingTone(object sender, EventArgs args) \{ View view = (View)sender; string title = view.FindViewById(Resource.Id.ringToneTitle).Text; RingToneItem ringToneItem = Items.First(rt => rt.Title == title); if (!ringToneItem.Selected) \{ //The RingTone was not selected and is selected now //Deselect Old and Select new foreach (RingToneItem oldItem in Items.Where(rt => rt.Selected)) \{ oldItem.Selected = false; \} // Select New RingTone ringToneItem.Selected = true; //Update the ListView. //This will result in removal of Selected state for all Items when the ListView updates it's layout NotifyDataSetChanged(); \} //Now play the test sound NotifierService.TestSound(Context, ringToneItem); \} public View SelectedItemView \{ get; set; \} \}