我有一個組合框，我希望它能夠自動查找并建議包含字典中任何單詞的短語。我找到了這個解決方案 -鏈接，但我注意到如果找不到該短語，則應用程式可能會崩潰 - 無效的引數值 0 對索引無效。試圖以各種可能的方式解決這個問題，但最終應用程式完全關閉。此解決方案中的錯誤是什么，是否有可能以某種方式修復它，如果找不到該短語，則顯示一個有關此問題的訊息框，例如 ..
該詞典包含與鏈接的第一個問題相同的短語：
門打開元素
外門內
門
滑動門
應用程式并不總是崩潰，我認為這是由于在初始字典的組合框中輸入的這些字母的存在
我在寫時迷戀：
orser
erot 等
并單擊視窗表單，
但是當我嘗試時沒有任何反應搜索：
abc
zui 等
我無法修復代碼，我希望你能。謝謝。
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApp
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
listOriginal.Add("Doors opening elements");
listOriginal.Add("exterior doors");
listOriginal.Add("interior doors");
listOriginal.Add("sliding doors");
this.comboBx.Items.AddRange(listOriginal.ToArray());
}
// Bind default keywords
List<string> listOriginal = new List<string>();
// save new keywords
List<string> listNew = new List<string>();
private void comboBx_TextUpdate(object sender, EventArgs e)
{
//clear combobox
this.comboBx.Items.Clear();
//clear listNew
listNew.Clear();
foreach (var item in listOriginal)
{
// call ToLower() .. not case sensitive
if (item.ToLower().Contains(this.comboBx.Text))
{
//add to ListNew
listNew.Add(item);
}
}
this.comboBx.Items.AddRange(listNew.ToArray());
this.comboBx.SelectionStart = this.comboBx.Text.Length;
Cursor = Cursors.Default;
// Automatically pop up drop-down
this.comboBx.DroppedDown = true;
}
}
}
編譯代碼后第 15 行出現例外：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
namespace WindowsFormsApp
{
static class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());// <-------- this
}
}
}
堆疊跟蹤：
System.ArgumentOutOfRangeException
HResult=0x80131502
Message=InvalidArgument=Value of '0' is not valid for 'index'.
Parameter name: index
Source=System.Windows.Forms
StackTrace:
at System.Windows.Forms.ComboBox.ObjectCollection.get_Item(Int32 index)
at System.Windows.Forms.ComboBox.get_Text()
at System.Windows.Forms.ComboBox.WmReflectCommand(Message& m)
at System.Windows.Forms.ComboBox.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.SendMessage(HandleRef hWnd, Int32 msg, IntPtr wParam, IntPtr lParam)
at System.Windows.Forms.Control.SendMessage(Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.Control.ReflectMessageInternal(IntPtr hWnd, Message& m)
at System.Windows.Forms.Control.WmCommand(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.Form.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at WindowsFormsApp.Program.Main() in C:\Users\denis\source\repos\WindowsFormsApp\WindowsFormsApp\Program.cs:line 15
uj5u.com熱心網友回復：
例外意味著集合中沒有專案。在這種情況下，TextUpdate 事件會清除 ComboBox 專案，并且當您在 ComboBox 沒有專案時單擊它時會發生例外。
解決此問題的方法是在 TextUpdate 事件結束時填充 ComboBox，并且僅在文本匹配時才操作下拉串列。如果 listOriginal 包含更新后的文本，則將 newList 添加到 ComboBox 并將 ComboBox.DroppedDown 設定為 true。否則，將 listOriginal 添加到 ComboBox 并將 ComboBox.DroppedDown 設定為 false。
private void comboBx_TextUpdate(object sender, EventArgs e)
{
//clear combobox
this.comboBx.Items.Clear();
//clear listNew
listNew.Clear();
foreach (var item in listOriginal)
{
// call ToLower() .. not case sensitive
if (item.ToLower().Contains(this.comboBx.Text.ToString()))
{
//add to ListNew
listNew.Add(item);
}
}
this.comboBx.SelectionStart = this.comboBx.Text.Length;
Cursor = Cursors.Default;
// Check if ListNew has been populated.
if (listNew.Count != 0)
{
this.comboBx.Items.AddRange(listNew.ToArray());
// Automatically pop up drop-down
this.comboBx.DroppedDown = true;
}
else
{
this.comboBx.Items.AddRange(listOriginal.ToArray());
// Automatically close dropdown
this.comboBx.DroppedDown = false;
}
}
肯定有更好的方法來解決這個錯誤，但我猜這是最簡單的修復。希望能幫助到你！
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