如何在 Xamarin 的 AlertDialog 中创建带有自定义适配器的列表视图 Android

Question

我正在尝试在 Xamarin 的 AllertDialog 中创建一个 ListView Android。

我搜索并找到了一些示例，但我没有在 AlertDialog 中找到任何使用 C# 的 ListView 和自定义适配器。

我找到的最接近样本的是下面的样本 (Thanks to Macoratti)。这个没有AlertDialog。我试图适应但我得到 System.NullReferenceException: 'Object reference not set to an instance of an object.'.

主要activity:

namespace App.CustomAdapterListView
{
    [Activity(Label = "App.CustomAdapterListView", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : Activity
    {
        protected override void OnCreate(Bundle bundle)
        {

            base.OnCreate(bundle);
            SetContentView(Resource.Layout.Main);

         /*  Original
            var filmesListView = FindViewById<ListView>(Resource.Id.filmeslistView);
            filmesListView.FastScrollEnabled = true;
            filmesListView.ItemClick += FilmesListView_ItemClick;
            var filmesAdapter = new FilmeAdapter(this, FilmesRepositorio.Filmes);
            filmesListView.Adapter = filmesAdapter;
         */


         var ViewAD = LayoutInflater.Inflate(Resource.Layout.Filmes, null);
         
         AlertDialog alertDialog;

         using (var dialog = new AlertDialog.Builder(this))
         {
            dialog.SetView(ViewAD);
            dialog.SetNegativeButton("Cancel", (s, a) => { });
            alertDialog = dialog.Create();
         }

         var adapter = new FilmeAdapter(this, FilmesRepositorio.Filmes);

// Here I get - System.NullReferenceException: 'Object reference not set to an instance of an object.'
         ViewAD.FindViewById<ListView>(Resource.Id.filmeslistView).Adapter = adapter; 

         alertDialog.Show();

        }

        private void FilmesListView_ItemClick(object sender, AdapterView.ItemClickEventArgs e)
        {
            Toast.MakeText(this, FilmesRepositorio.Filmes[e.Position].ToString(), ToastLength.Long).Show();
        }

    }
}

适配器class:

namespace App.CustomAdapterListView
{
    public class Filme
    {
        public int Id { get; set; }
        public string Titulo { get; set; }
        public string Diretor { get; set; }
        public DateTime DataLancamento { get; set; }

        public override string ToString()
        {
            return Titulo + " por " + Diretor;
        }
    }
}

适配器：

namespace App.CustomAdapterListView
{
     public class FilmeAdapter : BaseAdapter<Filme>
    {
        private readonly Activity context;
        private readonly List<Filme> filmes;

        public FilmeAdapter(Activity context, List<Filme> filmes)
        {
            this.context = context;
            this.filmes = filmes;
        }

        public override Filme this[int position]
        {
            get
            {
                return filmes[position];
            }
        }

        public override int Count
        {
            get
            {
                return filmes.Count;
            }
        }

        public override long GetItemId(int position)
        {
            return filmes[position].Id;
        }

        public override View GetView(int position, View convertView, ViewGroup parent)
        {
            var view = convertView ?? context.LayoutInflater.Inflate(Resource.Layout.Filmes, parent, false);

            var txtTitulo = view.FindViewById<TextView>(Resource.Id.tituloTextView);
            var txtDiretor = view.FindViewById<TextView>(Resource.Id.diretorTextView);
            var txtLancamento = view.FindViewById<TextView>(Resource.Id.dataLancamentoTextView);

            txtTitulo.Text = filmes[position].Titulo;
            txtDiretor.Text = "Dirigido por: " + filmes[position].Diretor;
            txtLancamento.Text = "Lançado em : " + filmes[position].DataLancamento.ToShortDateString();

            return view;
        }
    }
}

数据库：

namespace App.CustomAdapterListView
{
    public static class FilmesRepositorio
    {
        public static List<Filme> Filmes { get; private set; }

        static FilmesRepositorio()
        {
            Filmes = new List<Filme>();
            for (int i = 0; i < 10; i++)
            {
                AddFilmes();
            }

        }

        private static void AddFilmes()
        {
            Filmes.Add(new Filme
            {
                Id = 1,
                Titulo = "A New Hope",
                Diretor = "George Lucas",
                DataLancamento = new DateTime(1977, 05, 25)
            });

            Filmes.Add(new Filme
            {
                Id = 2,
                Titulo = "The Empire Strikes Back",
                Diretor = "George Lucas",
                DataLancamento = new DateTime(1980, 05, 17)
            });

            Filmes.Add(new Filme
            {
                Id = 3,
                Titulo = "O Reterono de Jedi",
                Diretor = "George Lucas",
                DataLancamento = new DateTime(1983, 05, 25)
            });

            Filmes.Add(new Filme
            {
                Id = 4,
                Titulo = "A ameaça fantasma",
                Diretor = "George Lucas",
                DataLancamento = new DateTime(1999, 05, 19)
            });

            Filmes.Add(new Filme
            {
                Id = 5,
                Titulo = "A vingança dos Sith",
                Diretor = "George Lucas",
                DataLancamento = new DateTime(2005, 05, 19)
            });

            Filmes.Add(new Filme
            {
                Titulo = "Marte",
                Diretor = "J.J. Abrams",
                DataLancamento = new DateTime(2015, 12, 11)
            });
        }
    }
}

主要布局 axml

<?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"
    android:minWidth="25px"
    android:minHeight="25px">
    <ListView
        android:minWidth="25px"
        android:minHeight="25px"
        android:background="#eee5d5"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/filmeslistView" />
</LinearLayout>

ListView的自定义布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="8dp">
    <TextView
        android:id="@+id/tituloTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#000000"
        android:textSize="20dp"
        android:textStyle="bold"
        android:paddingLeft="5dp" />
    <TextView
        android:id="@+id/diretorTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#00A14B"
        android:paddingLeft="5dp" />
    <TextView
        android:id="@+id/dataLancamentoTextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#7F3F97"
        android:paddingLeft="5dp" />
</LinearLayout>

抱歉这个菜鸟问题。我将不胜感激。

谢谢

Answer 1

您应该为包含 ListView 的视图创建一个 xml (dialogview.xml) 并为每个项目创建 xml (itemview.xml)列表视图。

例如：

创建 dialogview.xml:

<?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"
  android:minWidth="25px"
  android:minHeight="25px">
  <ListView
      android:minWidth="25px"
      android:minHeight="25px"
      android:background="#eee5d5"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:id="@+id/filmeslistView" />
</LinearLayout>

创建 itemview.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:padding="8dp">
  <TextView
    android:id="@+id/tituloTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="#000000"
    android:textSize="20dp"
    android:textStyle="bold"
    android:paddingLeft="5dp" />
  <TextView
    android:id="@+id/diretorTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="#00A14B"
    android:paddingLeft="5dp" />
  <TextView
    android:id="@+id/dataLancamentoTextView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textColor="#7F3F97"
    android:paddingLeft="5dp" />
</LinearLayout>

在您的 MainActivity 中：

 protected override void OnCreate(Bundle bundle)
    {

        base.OnCreate(bundle);
        SetContentView(Resource.Layout.Main);

        var ViewAD = LayoutInflater.Inflate(Resource.Layout.dialogview, null);
        var adapter = new FilmeAdapter(this, FilmesRepositorio.Filmes);
        ViewAD.FindViewById<ListView>(Resource.Id.filmeslistView).Adapter = adapter; 
       AlertDialog alertDialog;

       using (var dialog = new AlertDialog.Builder(this))
       { 
        dialog.SetView(ViewAD);
        dialog.SetNegativeButton("Cancel", (s, a) => { });
        alertDialog = dialog.Create();
       }

       alertDialog.Show();

    }

并在您的适配器中：

namespace App.CustomAdapterListView
{
 public class FilmeAdapter : BaseAdapter<Filme>
 {
    private readonly Activity context;
    private readonly List<Filme> filmes;

    public FilmeAdapter(Activity context, List<Filme> filmes)
    {
        this.context = context;
        this.filmes = filmes;
    }

    public override Filme this[int position]
    {
        get
        {
            return filmes[position];
        }
    }

    public override int Count
    {
        get
        {
            return filmes.Count;
        }
    }

    public override long GetItemId(int position)
    {
        return filmes[position].Id;
    }

    public override View GetView(int position, View convertView, ViewGroup parent)
    {
        var view = convertView ?? context.LayoutInflater.Inflate(Resource.Layout.itemview, parent, false);// inflate the xml for each item

        var txtTitulo = view.FindViewById<TextView>(Resource.Id.tituloTextView);
        var txtDiretor = view.FindViewById<TextView>(Resource.Id.diretorTextView);
        var txtLancamento = view.FindViewById<TextView>(Resource.Id.dataLancamentoTextView);

        txtTitulo.Text = filmes[position].Titulo;
        txtDiretor.Text = "Dirigido por: " + filmes[position].Diretor;
        txtLancamento.Text = "Lançado em : " + filmes[position].DataLancamento.ToShortDateString();

        return view;
    }
  }
}

更新

 var ViewAD = LayoutInflater.Inflate(Resource.Layout.dialogview, null);
 var adapter = new FilmeAdapter(this, FilmesRepositorio.Filmes);
 ListView listview =  ViewAD.FindViewById<ListView>(Resource.Id.filmeslistView);
 listview.Adapter = adapter; 
 listView.ItemClick += ListView_ItemClick;
 ...


 private void ListView_ItemClick(object sender, AdapterView.ItemClickEventArgs e)
 {
      //you could get the select data
 }

如何在 Xamarin 的 AlertDialog 中创建带有自定义适配器的列表视图 Android

How can I create a listview with custom adapter inside a AlertDialog in Xamarin Android

android

listview

xamarin