Question

我在我的代码中使用自定义ExpandableListViewAdapter。当我根据用户输入过滤代码时，应用程序正常工作。但是，当用户删除所述输入时，列表视图将保留最后一次搜索，然后在输入输入时变为空白。这是我的代码：主：

using Android.App;
using Android.Widget;
using Android.OS;
using System.Net;
using Java.Lang;
using System;
using Newtonsoft.Json.Linq;
using System.Linq;
using Java.Util;
using System.Threading;
using Org.Json;
using Android.Content;
using Android.Views;
using System.Collections.Generic;
using System.Text;
using RestSharp.Extensions.MonoHttp;
using Android.Text;

namespace DictionaryE
{
[Activity(Label = "DictionaryE", MainLauncher = true, Icon = "@drawable/logo")]
public class MainActivity : Activity
{
private ExpandableListView list;
private ExpandableListViewAdapter mAdapter;
private ArrayAdapter<string> adapter;
private int length;
private List<string> group= new List<string>();
private string[] names;
private Dictionary<string, List<string>> Mapout = new Dictionary<string, List<string>>();
private SearchView searchBar;
private View.IOnClickListener listener;


protected override void OnCreate(Bundle bundle)
{
    base.OnCreate(bundle);
    SetContentView(Resource.Layout.Main);
    ActionBar.Hide();
    // Set Views
    searchBar = FindViewById<SearchView>(Resource.Id.searchBar);
    list = FindViewById<ExpandableListView>(Resource.Id.lv);
    //Set Groups
    WebClient client = new WebClient();
    string json = client.DownloadString("********************");
    JSONArray myarray = new JSONArray(json);
    length = myarray.Length();
    names = new string[length];
    for (int i = 0; i < length; i++)
    {
        JSONObject Element = myarray.GetJSONObject(i);
        names[i] = Element.GetString("name");
    }
    setData(out mAdapter);
    list.SetAdapter(mAdapter);

    mAdapter.Filter.InvokeFilter();

}

private void setData(out ExpandableListViewAdapter mAdapter)
{
    string urlholder;
    string url;
    string json;
    string time;
    string timestamp;
    string together;
    WebClient client1 = new WebClient();
    for (int i=0;i < length; i++)
    {
        List<string> listplaceholder = new List<string>();
        group.Add(names[i]);
        urlholder = Uri.EscapeDataString(names[i]);
        url = "**********";
        json = client1.DownloadString(url);
        JSONArray array2 = new JSONArray(json);
        int length2 = array2.Length();
        for (int j = 0; j < length2; j++)
        {
            JSONObject Element = array2.GetJSONObject(j);
            time=Element.GetString("wait");
            JSONObject TimeElement = array2.GetJSONObject(j);
            timestamp = TimeElement.GetString("created_at");
            timestamp=timestamp.Replace("T", " at ");
            int index = timestamp.IndexOf(".");
            if (index > 0)
            {
                timestamp = timestamp.Substring(0, index);
            }
            together = time + " minutes posted at " + timestamp;
            listplaceholder.Add(together);
        }
        Mapout.Add(group[i], listplaceholder);


    }
    mAdapter = new ExpandableListViewAdapter(this, group, Mapout);
}
private void searchBar_QueryTextChange(object sender, SearchView.QueryTextChangeEventArgs e)
    {

        mAdapter.Filter.InvokeFilter(e.NewText);
    }

}
}

这是我的ExpandableListview适配器：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Java.Lang;

namespace BarStar
{
public class ExpandableListViewAdapter : BaseExpandableListAdapter, IFilterable
{
    private Context context;
    public List<string> listGroup;
    public Dictionary<string, List<string>> listChild;

    public ExpandableListViewAdapter(Context context, List<string> listGroup, Dictionary<string, List<string>> listChild)
    {
        this.context = context;
        this.listGroup = listGroup;
        this.listChild = listChild;
    }
    public override int GroupCount
    {
        get
        {
            return listGroup.Count;
        }
    }

    public override bool HasStableIds
    {
        get
        {
            return false;
        }
    }

    public Filter Filter => new GroupFilter(this);

    public override Java.Lang.Object GetChild(int groupPosition, int childPosition)
    {
        var result = new List<string>();
        listChild.TryGetValue(listGroup[groupPosition], out result);
        return result[childPosition];
    }

    public override long GetChildId(int groupPosition, int childPosition)
    {
        return childPosition;
    }

    public override int GetChildrenCount(int groupPosition)
    {
        var result = new List<string>();
        listChild.TryGetValue(listGroup[groupPosition], out result);
        return result.Count;
    }

    public override View GetChildView(int groupPosition, int childPosition, bool isLastChild, View convertView, ViewGroup parent)
    {
        if (convertView == null)
        {
            LayoutInflater inflater = (LayoutInflater)context.GetSystemService(Context.LayoutInflaterService);
            convertView = inflater.Inflate(Resource.Layout.Children, null);
        }
        TextView textViewItem = convertView.FindViewById<TextView>(Resource.Id.DataValue);
        string content = (string)GetChild(groupPosition, childPosition);
        textViewItem.Text = content;
        return convertView;
    }

    public override Java.Lang.Object GetGroup(int groupPosition)
    {
        return listGroup[groupPosition];
    }

    public override long GetGroupId(int groupPosition)
    {
        return groupPosition;
    }

    public override View GetGroupView(int groupPosition, bool isExpanded, View convertView, ViewGroup parent)
    {
        if (convertView == null)
        {
            LayoutInflater inflater = (LayoutInflater)context.GetSystemService(Context.LayoutInflaterService);
            convertView = inflater.Inflate(Resource.Layout.Groups, null);
        }
        string textGroup = (string)GetGroup(groupPosition);
        TextView textViewGroup = convertView.FindViewById<TextView>(Resource.Id.Header);
        textViewGroup.Text = textGroup;
        return convertView;
    }

    public override bool IsChildSelectable(int groupPosition, int childPosition)
    {
        return true;
    }


}

}

这是我的过滤类：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Java.Lang;

namespace BarStar
{
 class GroupFilter : Filter
{
    ExpandableListViewAdapter _adapter;
    ExpandableListViewAdapter placeholder;
    public GroupFilter(ExpandableListViewAdapter adapter)
    {
        _adapter = adapter;
    }
    protected override FilterResults PerformFiltering(ICharSequence constraint)
    {
        var returnObject = new FilterResults();
        if (constraint == null || constraint.Length() == 0)
        {
            // No filter implemented we return all the list
            returnObject.Values = _adapter;
            returnObject.Count = _adapter.listGroup.Count();
        }
        else
        {

            var tmpList = _adapter.listGroup.Where(g => g.ToLower().Contains(constraint.ToString().ToLower()));

            returnObject.Values = FromArray(tmpList.ToArray());
            returnObject.Count = tmpList.Count();
        }
        return returnObject;
    }

    protected override void PublishResults(ICharSequence constraint, FilterResults results)
    {
        if (results.Count == 0)
        {
            _adapter.NotifyDataSetInvalidated();
        }
        else
        {
            _adapter.listGroup = results.Values.ToArray<string>().ToList<string>();
            _adapter.NotifyDataSetChanged();
            constraint.Dispose();
            results.Dispose();
        }
    }


}

}

Answer 1

然而，当用户删除所述输入时，列表视图将保留最后一次搜索，然后在输入时将其变为空白

您需要对ExpandableListviewAdapter进行一些更改，以便根据您的用户输入动态更改：

在ExpandableListviewAdapter.cs中创建一个本地变量来存储过滤器，并在调用Filter的getter时不要创建新的过滤器：

public class ExpandableListViewAdapter : BaseExpandableListAdapter,IFilterable
{
   private GroupFilter _filter;
   ...
   public ExpandableListViewAdapter(Context context, List<string> listGroup, Dictionary<string, List<string>> listChild)
    {
        this.context = context;
        this.listGroup = listGroup;
        this.listChild = listChild;
        _filter = new GroupFilter(this);
    }
    ...
    public Filter Filter => _filter;
}

然后在Filter中创建一个新列表，以存储listGroup的原始数据：

private class GroupFilter : Filter
{
    List<string> _originalList;
    ...
    public GroupFilter(ExpandableListViewAdapter adapter)
    {
        _adapter = adapter;
        _originalList = new List<string>(adapter.listGroup);
    }

    ...
    protected override FilterResults PerformFiltering(ICharSequence constraint)
    {
        var returnObject = new FilterResults();

        //var tmpList= _originalList.Where(g => g.ToLower().Contains(constraint.ToString().ToLower()));
        //use LinQ to generate the filter result 
        var tmpList = from o in _originalList where o.ToLower().Contains(constraint.ToString().ToLower()) select o;

        returnObject.Values = FromArray(tmpList.ToArray());
        returnObject.Count = tmpList.Count();
        return returnObject;
    }
}

筛选方法在筛选后删除所有项目

1 个答案: