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();
}
}
}
}
答案 0 :(得分：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;
}
}