SetBackgroundColor 到自定义适配器上的列表视图项不起作用

Question

我有一个可以工作的自定义适配器，我已将其放入列表视图。
我现在成功添加了 15 个项目。

我现在尝试将项目 3 的背景颜色设置为橙色。 这项工作！

但是，当我向下和向上滚动时，背景颜色消失了。
我们如何防止这种情况发生？

//MENU.axml 与 listview1

MENU.axml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="#70292929"
    android:layout_gravity="top|right"
    android:orientation="horizontal">
      <ListView
          android:id="@+id/listview1"
          android:background="#1b4f72"
          android:layout_weight="0.5"
          android:layout_gravity="top|left"
          android:layout_width="10px"
          android:layout_height="match_parent">
      </ListView>
</LinearLayout>

//向listview1添加项目并尝试将项目3的背景设置为橙色的C#代码

Android.Views.View MENUVIEW = LayoutInflater.Inflate(Resource.Layout.MENU, null);
ListView LISTVIEW1 = MENUVIEW.FindViewById<ListView>(Resource.Id.listview1);

                //Add Items to the listview1
                List<String> itemLIST = new List<String>(); 
                for (int i = 0; i < 15; i++)
                {
                    itemLIST.Add("hello" + i); 
                }
                Adapter1 adapter1 = new Adapter1(this, Android.Resource.Layout.SimpleListItem1, itemLIST);
                LISTVIEW1.Adapter = adapter1;

//Set backgroundcolor on item 3
LISTVIEW1.GetChildAt(3).SetBackgroundColor(Android.Graphics.Color.Orange);
TextView tview = listview.GetChildAt(3).FindViewById<TextView>(Resource.Id.itemtext);
tview.SetBackgroundColor(Android.Graphics.Color.Orange);

//适配器1的代码

   class Adapter1 : BaseAdapter
    {

        Context context;
        int item = 0;
        List<String> items = new List<String>();

        public Adapter1(Context context, int resource, List<String> itemArray)
        {
            items = itemArray;
            item = resource;
            this.context = context;
        }
   

        public override Java.Lang.Object GetItem(int position)
        {
            return position;
        }

        public override long GetItemId(int position)
        {
            return position;
        }
        
        public String getItem(int position)
        {
            return items[position]; //returns list item at the specified position
        }
        public override int GetItemViewType(int position)
        {
            return position;
        }
        

        public override View GetView(int position, View convertView, ViewGroup parent)
        {
            var view = convertView;
            Adapter1ViewHolder holder = null;
           

            if (holder == null)
            {
                holder = new Adapter1ViewHolder();
                var inflater = context.GetSystemService(Context.LayoutInflaterService).JavaCast<LayoutInflater>();

                view = inflater.Inflate(Resource.Layout.textview, parent, false);
                String currentItem = getItem(position);

                //get the TextView for item name and item description
                TextView textViewItemName = view.FindViewById<TextView>(Resource.Id.itemtext);

                //sets the text for item name and item description from the current item object
                textViewItemName.SetText(currentItem, TextView.BufferType.Normal);

                holder.Title = textViewItemName;
                holder.Title.Text = currentItem;
                view.Tag = holder;
            }
            return view;
        }

        //Fill in cound here, currently 0
        public override int Count
        {
            get
            {
                return items.Count;
            }
        }
    }

    class Adapter1ViewHolder : Java.Lang.Object
    {
        //Your adapter views to re-use
        public TextView Title { get; set; }
    }

Answer 1

您应该尝试使用 Adapter1 中的#getView 方法更新颜色。

  int orangeColorPosition = -1;

  public void setOrangeColorPosition(int position){
      this.orangeColorPosition = position;
      notifyDataSetChanged();
  }

  public override View GetView(int position, View convertView, ViewGroup parent)
    {
        ...
        if(position == orangeColorPosition ){
                // set background color here
        }
        return view;
    }

然后调用 adapter1.setOrangeColorPosition(3);应该更新位置的颜色

Answer 2

使用

setBackgroundResource(R.color.Orange);