用于递归绑定到 ListView 的自定义 ArrayAdapter

Question

我有一个层次结构的类别列表，我想使用自定义数组适配器在具有递归 ListView 的布局中呈现这些列表。每个类别都可以有任何深度的子类别。

为了简单起见，现在假设类别只有标题和子类别数组（同样只有标题）。在下面的示例中，有 3 个顶级类别。第一个顶级类别有 3 个子类别。第一个子类别又具有 3 个子类别。

    public class MyListActivity : Activity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            SetContentView(Resource.Layout.my_list);


            List<CategoryItem> categories = new List<CategoryItem>();


            categories.Add(new CategoryItem("Category 1"));
            categories.Add(new CategoryItem("Category 2"));
            categories.Add(new CategoryItem("Category 3"));

            categories[0].Children.Add(new CategoryItem("Sub 11"));
            categories[0].Children.Add(new CategoryItem("Sub 12"));
            categories[0].Children.Add(new CategoryItem("Sub 13"));


            categories[0].Children[0].Children.Add(new CategoryItem("Sub Sub 111"));
            categories[0].Children[0].Children.Add(new CategoryItem("Sub Sub 112"));
            categories[0].Children[0].Children.Add(new CategoryItem("Sub Sub 113"));

            ListView listView = FindViewById<ListView>(Resource.Id.listView1);

            CategoryAdaptor adaptor = new CategoryAdaptor(Android.App.Application.Context, categories);

            listView.Adapter = adaptor;

            // Create your application here
        }
    }

这是 listView 的自定义适配器。请注意，它是在 GetView 中递归调用另一个列表视图

    public class CategoryAdaptor : ArrayAdapter<CategoryItem>
    {

        string TAG = "CategoryAdaptor";

        List<CategoryItem> categories;
        Context context;

        public CategoryAdaptor(Context context, List<CategoryItem> categories) : base(context, 0, categories)
        {
            this.context = context;
            this.categories = categories;
        }

        public override View GetView(int position, View convertView, ViewGroup parent)
        {
            Log.Debug(TAG, "GetView called for position - " + position);

            //For now ignore convertView...which is perfectly legal
            var listItem = LayoutInflater.From(context).Inflate(Resource.Layout.category_list_item, parent, false);

            Log.Debug(TAG, "Binding - " + categories[position].Title);

            listItem.FindViewById<TextView>(Resource.Id.textView1).Text = categories[position].Title;


            if (categories[position].Children.Count > 0)
            {
                var childView = listItem.FindViewById<ListView>(Resource.Id.childItems);
                var childAdaptor = new CategoryAdaptor(context, categories[position].Children);
                childView.Adapter = childAdaptor;
            }


            return listItem;

        }

    }

主布局包含一个列表视图。我还删除了布局文件上的所有格式，以减少代码噪音。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <ListView
        android:minWidth="25px"
        android:minHeight="250px"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listView1" />



</LinearLayout>

列表视图中的项目具有自定义适配器设置的以下模板。请注意，这有另一个列表视图，以便可以递归地显示每个类别的子视图。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:text="Small Text"
        android:textAppearance="?android:attr/textAppearanceSmall"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minWidth="25px"
        android:minHeight="25px"
        android:id="@+id/textView1" />
    <ListView
        android:minWidth="25px"
        android:minHeight="250px"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/childItems" />
</LinearLayout>

但是，代码似乎没有输出预期的结果。只有子类别中的第一项被渲染，如下图所示。看到它缺少第 2 和第 3 子类别。任何指针将不胜感激。

Answer 1

设置ListView的Adapter后，ListView的高度是根据ListView的子项重新计算的，所以我们需要将ListView的高度设置为LayoutParams。

你可以试试下面的代码：

类实用程序

public class Utility
{
    public static void setListViewHeightBasedOnChildren(ListView listView)
    {
        {
            if (listView.Adapter == null)
            {
                // pre-condition
                return;
            }

            int totalHeight = listView.PaddingTop + listView.PaddingBottom;
            for (int i = 0; i < listView.Count; i++)
            {
                View listItem = listView.Adapter.GetView(i, null, listView);
                if (listItem.GetType() == typeof(ViewGroup))
                {
                    listItem.LayoutParameters = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MatchParent, ViewGroup.LayoutParams.WrapContent);
                }
                listItem.Measure(0, 0);
                totalHeight += listItem.MeasuredHeight;
            }

            listView.LayoutParameters.Height = totalHeight + (listView.DividerHeight * (listView.Count - 1));
        }
    }
}

并像这样在CategoryAdaptor 中使用它：

public class CategoryAdaptor: ArrayAdapter<CategoryItem>
{
    string TAG = "CategoryAdaptor";

    List<CategoryItem> categories;
    Context context;

    public CategoryAdaptor(Context context, List<CategoryItem> categories) : base(context, 0, categories)
    {
        this.context = context;
        this.categories = categories;
    }

    public override View GetView(int position, View convertView, ViewGroup parent)
    {
        Log.Debug(TAG, "GetView called for position - " + position);

        //For now ignore convertView...which is perfectly legal
        var listItem = LayoutInflater.From(context).Inflate(Resource.Layout.category_list_item, parent, false);

        Log.Debug(TAG, "Binding - " + categories[position].Title);

        listItem.FindViewById<TextView>(Resource.Id.textView1).Text = categories[position].Title;


        if (categories[position].Children.Count > 0)
        {
            Log.Info("123456","");

            var childView = listItem.FindViewById<ListView>(Resource.Id.childItems);
            var childAdaptor = new CategoryAdaptor(context, categories[position].Children);
            childView.Adapter = childAdaptor;
             // call method : setListViewHeightBasedOnChildren after you set Adapter
            Utility.setListViewHeightBasedOnChildren(childView);
        }


        return listItem;

    }
}

效果是：