如何解决自定义 ListView 中的 BaseAdapter,如何使其在空视图中更加健壮
我有这段代码通常可以正常工作,但在某些装有 Android 9 的设备中,只有我收到此异常:
HistoryListViewAdapter+<>c__displayClass8_0.<GetView>b__0 ()
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
jnienvironment+Staticmethods.CallStaticObjectMethod (Java.Interop.JniObjectReference type,Java.Interop.JniMethodInfo method,Java.Interop.JniArgumentValue* args)
JniPeerMembers+JniStaticmethods.InvokeObjectMethod (System.String encodedMember,Java.Interop.JniArgumentValue* parameters)
HtmlCompat.FromHtml (System.String source,system.int32 flags)
HistoryListViewAdapter+<>c__displayClass8_0.<GetView>b__0 ()
MainThread.BeginInvokeOnMainThread (System.Action action)
HistoryListViewAdapter.GetView (system.int32 position,Android.Views.View convertView,Android.Views.ViewGroup parent)
BaseAdapter.n_GetView_ILandroid_view_View_Landroid_view_ViewGroup_ (system.intPtr jnienv,system.intPtr native__this,system.int32 position,system.intPtr native_convertView,system.intPtr native_parent)
androidx.core.text.HtmlCompat.fromHtml HtmlCompat.java:148
crc64441aa66e1467637c.HistoryListViewAdapter.n_getView(Native Method)
crc64441aa66e1467637c.HistoryListViewAdapter.getView HistoryListViewAdapter.java:56
android.widget.AbsListView.obtainView AbsListView.java:2375
androidx.viewpager.widget.ViewPager.onLayout ViewPager.java:1775
android.view.View.layout View.java:20871
androidx.coordinatorlayout.widget.CoordinatorLayout.onLayout CoordinatorLayout.java:918
android.view.View.layout View.java:20871
androidx.drawerlayout.widget.DrawerLayout.onLayout DrawerLayout.java:1263
android.view.View.layout View.java:20871
我猜测问题出在我的适配器上,需要改进以更有效地处理所有情况,但我不确定如何改进我的代码,这是我的适配器代码:
using Android.App;
using Android.Views;
using Android.Widget;
using AndroidX.Core.Text;
using System.Collections.Generic;
using Xamarin.Essentials;
namespace KinoStats
{
public class HistoryListViewAdapter : BaseAdapter<string>
{
private readonly Activity Activity;
private readonly List<string> Data;
public HistoryListViewAdapter(Activity Activity,List<string> Data) : base()
{
this.Activity = Activity;
this.Data = Data;
}
public override string this[int position] => Data[position];
public override int Count => Data.Count;
public override long GetItemId(int position)
{
return position;
}
public override View GetView(int position,View convertView,ViewGroup parent)
{
if (convertView == null)
convertView = Activity.LayoutInflater.Inflate(Resource.Layout.SingleHistoryListViewItem,null);
var historyItemTextView = convertView.FindViewById<TextView>(Resource.Id.HistoryItemTextView);
MainThread.BeginInvokeOnMainThread(() =>
{
historyItemTextView.SetText(
HtmlCompat.FromHtml(Data[position],HtmlCompat.FromHtmlModeLegacy),TextView.BufferType.Spannable);
});
return convertView;
}
}
}
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