如何将单独的参数传递给 Xamarin Android C# 中的 ListView.ItemClick 调用

Posted 2023-04-19

【中文标题】如何将单独的参数传递给 Xamarin Android C# 中的 ListView.ItemClick 调用

【英文标题】：How to pass a separate argument through to a ListView.ItemClick call in Xamarin Android C#

【发布时间】：2020-06-10 21:17:40

【问题描述】：

所以我试图将参数传递给 ListView.ItemClick 调用，但我似乎无法弄清楚如何在没有任何错误的情况下做到这一点，这是我的代码：

 public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    
        base.OnCreateView(inflater, container, savedInstanceState);
        var view = inflater.Inflate(Resource.Layout.Dialog_Load, container, false);

        mListView = view.FindViewById<ListView>(Resource.Id.LoadListView);
        var responseResult = Load(UserID).Result;

        //Creates an array that contains all the different names and IDs
        string[] responseList = responseResult.Split(",");
        //Using lists to hold the different number of values as they can expand dynamically as opposed to a static array
        var ProgressionIDs = new List<string>();
        var ProgressionNames = new List<string>();

        //Separates ChordProgressionID from ChordProgressionName
        for (int index = 0; index < responseList.Length; index++)
        
            if (int.TryParse(responseList.ElementAt(index), out _))
            
                ProgressionIDs.Add(responseList.ElementAt(index));
            
            else if (responseList.ElementAt(index) == "")
            
                //Stops the last comma from responseResult creating an empty slot in the array,
                //which would create an unwanted empty item in the listview.
            
            else
            
                ProgressionNames.Add(responseList.ElementAt(index));
            
        

        //Converts name list to array so that it can be set to the adapter
        string[] ProgressionNamesArr = new string[ProgressionNames.Count()];
        ProgressionNamesArr = ProgressionNames.ToArray();

        ArrayAdapter<string> adapter = new ArrayAdapter<string>(this.Activity, android.Resource.Layout.SimpleListItem1, ProgressionNamesArr);
        mListView.Adapter = adapter;

        mListView.ItemClick += mListView_ItemClick;

        return view;
    
    public void mListView_ItemClick(object sender, AdapterView.ItemClickEventArgs e)
    
        int position = e.Position;
        var id = ProgressionIDs[e.Position];

    

    private async Task<string> Load(string UserID)
    
        //User has clicked the save button
        HttpClient client = new HttpClient();
        Uri uri = new Uri("**some url**");

        HttpContent formContent = new FormUrlEncodedContent(new[]
        
            new KeyValuePair<string, string>("UserID", UserID),
        );

        //Gets a response in terms of connection to the server
        HttpResponseMessage response = await client.PostAsync(uri, formContent);

        response.EnsureSuccessStatusCode();

        //Gets 'echo' response from php file.
        string responseResult = await response.Content.ReadAsStringAsync();
        return responseResult;

    

我知道我现在拥有的 OnClick 子例程没有意义，因为我实际上并没有发送 ProgressionIDs 的实例。

我需要知道解决此问题的方法，以便我可以获取在 mListView 上单击的项目的位置，然后在该位置选择 ProgressionIDs 并将其存储在变量中。

【参考方案1】：

你能给我一个数据结构吗？一个 ProgressionName 对应一个 ProgressionID？

如果是这样，您可以为Progression 创建一个模型，其中包含两个属性，如以下数据结构。

   public class Progression


    public string ProgressionIDs  get; set; 
    public string ProgressionNames  get; set; 

我使用静态数据来填充List<Progression>。在listview中点击item可以获取postion，然后录制到postion获取List<Progression>中的名字

  List<Progression> progressions;
    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    


        View view = inflater.Inflate(Resource.Layout.layout1, container, false);
        ListView listView1 = view.FindViewById<ListView>(Resource.Id.listView1);
        progressions = new List<Progression>();

        progressions.Add(new Progression()  ProgressionIDs="1" , ProgressionNames= "Vegetables" );
        progressions.Add(new Progression()  ProgressionIDs = "2", ProgressionNames = "Fruits" );
        progressions.Add(new Progression()  ProgressionIDs = "3", ProgressionNames = "Flower Buds" );
        progressions.Add(new Progression()  ProgressionIDs = "4", ProgressionNames = "Legumes" );
        progressions.Add(new Progression()  ProgressionIDs = "5", ProgressionNames = "Bulbs" );
       progressions.Add(new Progression()  ProgressionIDs = "6", ProgressionNames = "Tubers" );
        var myAdapter=new MyAdapter(this.Activity, progressions);
        listView1.Adapter = myAdapter;

        listView1.ItemClick += ListView1_ItemClick;
        return view;

    

    private void ListView1_ItemClick(object sender, AdapterView.ItemClickEventArgs e)
    
        var myPostion= e.Position;
        Progression progression = progressions[myPostion];
        Toast.MakeText(this.Activity,progression.ProgressionIDs+" "+progression.ProgressionNames,ToastLength.Short).Show();

    

您应该为您的列表视图适配器创建 BaseAdapter。

      public class MyAdapter : BaseAdapter<Progression>

    private Activity mActivity;
    private List<Progression> items;

    public MyAdapter(Activity mActivity, List<Progression>  progressions)
    
        this.mActivity = mActivity;
        this.items = progressions;
    


    public override Progression this[int position] => items[position];



    public override int Count => items.Count();

    public override long GetItemId(int position)
    
        return position;
    

    public override View GetView(int position, View convertView, ViewGroup parent)
    
        View view = convertView;
        if (view == null) // no view to re-use, create new
            view = mActivity.LayoutInflater.Inflate(Resource.Layout.SimpleListItem1, null);
        view.FindViewById<TextView>(Resource.Id.textView1).Text = items[position].ProgressionIDs;
        view.FindViewById<TextView>(Resource.Id.textView2).Text = items[position].ProgressionNames;

        return view;
    

这里的代码与SimpleListItem1相关。

   <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_
    android:layout_>
    <TextView
        android:layout_
        android:layout_
        android:id="@+id/textView1"
        android:text="test1"
        android:layout_marginRight="@dimen/abc_action_bar_content_inset_material"
    />

 <TextView
        android:layout_
        android:layout_
        android:id="@+id/textView2"
        android:text="test2"
    />
</LinearLayout>

这里正在运行 GIF。

【讨论】：

我试试这个，有没有办法让元素变大？我正在使用对话框片段来显示列表视图，我向用户显示的只是名称，我使用的是 ID，所以当我点击某些东西时，它会使用与名称相关的 ID 从服务器中获取其他数据

如果要让元素变大，请在SimpleListItem1中设置android:textSize="30dp"为TextView

好的，现在我的程序根本不会加载对话框片段，然后它会说应用程序在等待后没有响应。

没关系，我设法解决了！原来我在 OnCreateView 中做的太多了，所以我不得不在前一个片段中进行数据库调用并传递值，然后它实际上开始像你的 gif 那样加载。