blocks|key|1240177|text|很难仅从代码中扣除，但我认为您的过滤问题是从不同方面产生的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1240178|(+a)您需要一个显示在Model上的数据的ListBox。你需要一个收藏“物品”的地方(Dictionary，DataBase，XML，BinaryFile，Collection)，简而言之，就是某种商店。|offset|length|style|CODE|1240179|要在UI上显示数据，总是从存储区中选择数据，过滤并放到UI中。|BOLD|1240180|(+b)在第一点之后，过滤代码可以如下所示(伪代码)|1240181|var+registrationsList+=+DataStore.ToList();+//return+original+data+from+Store

registrationListBox.BeginUpdate();
registrationListBox.Items.Clear();

if(!string.IsNullOrEmpty(SrchBox.Text))+
{
++foreach+(string+str+in+registrationsList)
++{++++++++++++++++
+++++if+(str.Contains(SrchBox.Text))
+++++{
+++++++++registrationListBox.Items.Add(str);
+++++}
++}
}
else+
+++registrationListBox.Items.AddRange(registrationsList);+//there+is+no+any+filter+string,+so+add+all+data+we+have+in+Store

registrationListBox.EndUpdate();|code-block|syntax|javascript|1240182|希望这能有所帮助。|1240183|entityMap^0|0|C|5|M|7|19|A|1K|8|1T|3|1X|A|28|A|0|A|2|0|0|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@$D|X|E|Y|F|G]|$D|Z|E|10|F|G]|$D|11|E|12|F|G]|$D|13|E|14|F|G]|$D|15|E|16|F|G]|$D|17|E|18|F|G]|$D|19|E|1A|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1B|8|@$D|1C|E|1D|F|J]]|9|@]|A|$]]|$1|K|3|L|5|6|7|1E|8|@]|9|@]|A|$]]|$1|M|3|N|5|O|7|1F|8|@]|9|@]|A|$P|Q]]|$1|R|3|S|5|6|7|1G|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|U|$]]

It's hard to deduct just from the code, but I presume your filtering problem born from the different aspects: 

a) You need a <code>Model</code> of the data shown on <code>ListBox</code>. You need a colleciton of "Items" which you hold somewhere (<code>Dictionary</code>, <code>DataBase</code>, <code>XML</code>, <code>BinaryFile</code>, <code>Collection</code>), some kind of Store in short. 

To show the data on UI you always pick the data from that Store, filter it and put it on UI. 

b) After the first point your filtering code can look like this (a pseudocode) 

<pre><code>var registrationsList = DataStore.ToList(); //return original data from Store

registrationListBox.BeginUpdate();
registrationListBox.Items.Clear();

if(!string.IsNullOrEmpty(SrchBox.Text)) 
{
 foreach (string str in registrationsList)
 { 
 if (str.Contains(SrchBox.Text))
 {
 registrationListBox.Items.Add(str);
 }
 }
}
else 
 registrationListBox.Items.AddRange(registrationsList); //there is no any filter string, so add all data we have in Store

registrationListBox.EndUpdate();
</code></pre>

Hope this helps.

blocks|key|2119157|text|像这样的东西可能对你有用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2119158|var+itemList+=+registrationListBox.Items.Cast<string>().ToList();
if+(itemList.Count+>+0)
{
++++//clear+the+items+from+the+list
++++registrationListBox.Items.Clear();

++++//filter+the+items+and+add+them+to+the+list
++++registrationListBox.Items.AddRange(
++++++++itemList.Where(i+=>+i.Contains(SrchBox.Text)).ToArray());
}|code-block|syntax|javascript|2119159|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Something like this might work for you:

<pre><code>var itemList = registrationListBox.Items.Cast&lt;string&gt;().ToList();
if (itemList.Count &gt; 0)
{
 //clear the items from the list
 registrationListBox.Items.Clear();

 //filter the items and add them to the list
 registrationListBox.Items.AddRange(
 itemList.Where(i =&gt; i.Contains(SrchBox.Text)).ToArray());
}
</code></pre>

blocks|key|1271741|text|是的，这就是过滤的答案。(修改了一点)。我在文本文件里找到了信息。这就是对我起作用的东西|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1271742|FileInfo+registrationsText+=+new+FileInfo(@"name_temp.txt");
++++++++++++StreamReader+registrationsSR+=+registrationsText.OpenText();
++++++++++++var+registrationsList+=+registrationListBox.Items.Cast<string>().ToList();

++++++++++++registrationListBox.BeginUpdate();
++++++++++++registrationListBox.Items.Clear();

++++++++++++if+(!string.IsNullOrEmpty(SrchBox.Text))
++++++++++++{
++++++++++++++++foreach+(string+str+in+registrationsList)
++++++++++++++++{
++++++++++++++++++++if+(str.Contains(SrchBox.Text))
++++++++++++++++++++{
++++++++++++++++++++++++registrationListBox.Items.Add(str);
++++++++++++++++++++}
++++++++++++++++}
++++++++++++}
++++++++++++else
++++++++++++++++while+(!registrationsSR.EndOfStream)
++++++++++++++++{
++++++++++++++++++++registrationListBox.Items.Add(registrationsSR.ReadLine());
++++++++++++++++}
++++++++++++registrationListBox.EndUpdate();|code-block|syntax|javascript|1271743|似乎这一错误：|1271744|1271745|对象引用未设置为对象的实例|blockquote|1271746|1271747|1271748|来自我代码中的其他地方，不能把手指放在上面。|1271749|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|W|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|X|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|Z|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|R|$]]

Yes that was the answer to filtering. (modified a bit). I had the info in a text file. This is what worked for me 

<pre><code>FileInfo registrationsText = new FileInfo(@"name_temp.txt");
 StreamReader registrationsSR = registrationsText.OpenText();
 var registrationsList = registrationListBox.Items.Cast&lt;string&gt;().ToList();

 registrationListBox.BeginUpdate();
 registrationListBox.Items.Clear();

 if (!string.IsNullOrEmpty(SrchBox.Text))
 {
 foreach (string str in registrationsList)
 {
 if (str.Contains(SrchBox.Text))
 {
 registrationListBox.Items.Add(str);
 }
 }
 }
 else
 while (!registrationsSR.EndOfStream)
 {
 registrationListBox.Items.Add(registrationsSR.ReadLine());
 }
 registrationListBox.EndUpdate();
</code></pre>

It seems that the error:

<blockquote>
 Object reference not set to an instance of an object
</blockquote>

is from somewhere else in my code, can't put my finger on it.

blocks|key|2119190|text|如果可以的话，把所有的东西都存储在字典里，然后从那里填充。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2119191|public+partial+class+myForm+:+Form
{
++++private+Dictionary<string,+string>+myDictionary+=+new+Dictionary<string,+string>();
//constructor.+populates+the+items.+Assumes+there+is+a+listbox+(myListbox)+and+a+textbox+(myTextbox),+named+respectively
public+myForm()
{
++++InitializeComponent();
++++myDictionary.Add("key1",+"item1");
++++myDictionary.Add("key2",+"My+Item");
++++myDictionary.Add("key3",+"A+Thing");

++++//populate+the+listbox+with+everything+in+the+dictionary
++++foreach+(string+s+in+myDictionary.Values)
++++++++myListbox.Add(s);
}
//make+sure+to+connect+this+to+the+textbox+change+event
private+void+myTextBox_TextChanged(object+sender,+EventArgs+e)
{
++++myListbox.BeginUpdate();
++++myListbox.Items.Clear();
++++foreach+(string+s+in+myDictionary.Values)
++++{
++++++++if+(s.Contains(myListbox.Text))
++++++++++++myListbox.Items.Add(s);
++++}
++++myListbox.EndUpdate();
}
}|code-block|syntax|javascript|2119192|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If able, store everything in a dictionary and just populate it from there.

<pre><code>public partial class myForm : Form
{
 private Dictionary&lt;string, string&gt; myDictionary = new Dictionary&lt;string, string&gt;();
//constructor. populates the items. Assumes there is a listbox (myListbox) and a textbox (myTextbox), named respectively
public myForm()
{
 InitializeComponent();
 myDictionary.Add("key1", "item1");
 myDictionary.Add("key2", "My Item");
 myDictionary.Add("key3", "A Thing");

 //populate the listbox with everything in the dictionary
 foreach (string s in myDictionary.Values)
 myListbox.Add(s);
}
//make sure to connect this to the textbox change event
private void myTextBox_TextChanged(object sender, EventArgs e)
{
 myListbox.BeginUpdate();
 myListbox.Items.Clear();
 foreach (string s in myDictionary.Values)
 {
 if (s.Contains(myListbox.Text))
 myListbox.Items.Add(s);
 }
 myListbox.EndUpdate();
}
}
</code></pre>

blocks|key|1240286|text|我会这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1240287|private+List<string>+registrationsList;

private+void+SrchBox_TextChanged_1(object+sender,+EventArgs+e)
{
++registrationListBox.BeginUpdate();
++registrationListBox.Items.Clear();

++var+filteredList+=+registrationList.Where(rl+=>+rl.Contains(SrchBox.Text))

++registrationListBox.Items.AddRange();

++registrationListBox.EndUpdate();
}|code-block|syntax|javascript|1240288|只需记住，当您第一次填充列表框时，要填充registrationsList。|1240289|希望这能有所帮助。|1240290|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I would do it like this:

<pre><code>private List&lt;string&gt; registrationsList;

private void SrchBox_TextChanged_1(object sender, EventArgs e)
{
 registrationListBox.BeginUpdate();
 registrationListBox.Items.Clear();

 var filteredList = registrationList.Where(rl =&gt; rl.Contains(SrchBox.Text))

 registrationListBox.Items.AddRange();

 registrationListBox.EndUpdate();
}
</code></pre>

Just remember to populate registrationsList the first time you fill your listbox.

Hope this helps.

blocks|key|2119252|text|这对我来说是一个非常困难的问题，但我找到了一个适合我的解决办法(不是那么简单)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2119253|在aspx页面上：|2119254|<input+id="ss"+type="text"+oninput="writeFilterValue()"/>
<asp:HiddenField+ID="hf1"+runat="server"+Value=""+ClientIDMode="Static"+/>|code-block|syntax|javascript|2119255|我需要HTML输入类型，因为“input”函数，这是不可用的经典asp.net控件。writeFilterValue()函数会导致回发，该回发将过滤给定ListBox的值(在代码隐藏中)。|2119256|我定义了两个javascript函数：|2119257|++++<script+type="text/javascript">

++++function+writeFilterValue()+{
++++++++var+bla+=+document.getElementById("ss").value;
++++++++$("#hf1").val(bla)
++++++++__doPostBack();
++++}

++++function+setTboxValue(s)+{
++++++++document.getElementById('ss').value+=+s;
++++++++document.getElementById('ss').focus();
++++}

</script>|2119258|现在，您可以在代码隐藏上使用回发来捕获hf1值，每次在inputbox上输入单个字符时。关于代码隐藏：|2119259|++++If+IsPostBack+Then
++++++++FiltraLbox(hf1.Value)
++++End+If|2119260|函数FiltraLbox(hf1.Value)更改Listbox的数据源，并重新绑定它：|2119261|Public+Sub+FiltraLbox(ByVal+hf+As+String)

++++If+hf+<>+""+Then


++++'+change+datasource+here,+that+depends+on+hf+value,


++++++++ListBox1.DataBind()

++++++++ScriptManager.RegisterStartupScript(Page,+Page.GetType(),+"text",+setTboxValue('"+%2B+hf+%2B+"');",+True)
++++End+If

End+Sub|2119262|最后，我调用函数setTboxValue()，它重写回发时丢失的输入文本值，并将焦点放在它上。|2119263|尽情享受吧。|2119264|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|13|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|15|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|16|8|@]|9|@]|A|$]]|$1|M|3|N|5|F|7|17|8|@]|9|@]|A|$G|H]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|F|7|19|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|1A|8|@]|9|@]|A|$]]|$1|U|3|V|5|F|7|1B|8|@]|9|@]|A|$G|H]]|$1|W|3|X|5|6|7|1C|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1D|8|@]|9|@]|A|$]]|$1|10|3|-4|5|6|7|1E|8|@]|9|@]|A|$]]]|11|$]]

it was a very hard issue for me, but I found a workaround (not so simple) that works fine for me.

on aspx page:

<pre><code>&lt;input id="ss" type="text" oninput="writeFilterValue()"/&gt;
&lt;asp:HiddenField ID="hf1" runat="server" Value="" ClientIDMode="Static" /&gt;
</code></pre>

I need HTML input type because of "oninput" function, that is not availiable on classic asp.net controls. The writeFilterValue() function causes a postback that filters values of a given ListBox (in code-behind).

I've defined this two javascript function:

<pre><code> &lt;script type="text/javascript"&gt;

 function writeFilterValue() {
 var bla = document.getElementById("ss").value;
 $("#hf1").val(bla)
 __doPostBack();
 }

 function setTboxValue(s) {
 document.getElementById('ss').value = s;
 document.getElementById('ss').focus();
 }

&lt;/script&gt;
</code></pre>

You can now use postback on code-behind to capture hf1 value, every time some single Character is typed on inputbox.
On code-behind:

<pre><code> If IsPostBack Then
 FiltraLbox(hf1.Value)
 End If
</code></pre>

The function FiltraLbox(hf1.Value) changes datasource of Listbox, and rebind it:

<pre><code>Public Sub FiltraLbox(ByVal hf As String)

 If hf &lt;&gt; "" Then


 ' change datasource here, that depends on hf value,


 ListBox1.DataBind()

 ScriptManager.RegisterStartupScript(Page, Page.GetType(), "text", setTboxValue('" + hf + "');", True)
 End If

End Sub
</code></pre>

At the end I call the function setTboxValue(), that rewrites the input text value lost on postback, and puts the focus on it.

Enjoy it.

I am trying to filter an listbox with text from a textbox, realTime. 

Here is the code:

<pre><code>private void SrchBox_TextChanged_1(object sender, EventArgs e)
{
 var registrationsList = registrationListBox.Items.Cast&lt;String&gt;().ToList();
 registrationListBox.BeginUpdate();
 registrationListBox.Items.Clear();
 foreach (string str in registrationsList)
 {
 if (str.Contains(SrchBox.Text))
 {
 registrationListBox.Items.Add(str);
 }
 }
 registrationListBox.EndUpdate();
}
</code></pre>

Here are the issues:

<ol>
<li>When I run the program i get this error: <code>Object reference not set to an instance of an object</code></li>
<li>If I hit backspace, my initial list is not shown anymore. This is because my actual list of items is now reduced, but how can I achieve this?</li>
</ol>

Can you point me in the right direction?

Filter ListBox with TextBox in realtime

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在尝试使用文本框realTime中的文本筛选列表框。以下是代码：private void SrchBox_TextChanged_1(object sender, EventArgs e){ var registrationsList = registrationListBox.Items.Cast<String...

问利用ListBox对TextBox进行实时滤波
EN

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