我有一个Winforms ComboBox，其中包含自定义类的实例。当项目首次添加到ComboBox的项目集合中时，ToString方法会调用每个项目。
但是，当用户更改运行应用程序的语言时，ToString方法的结果会更改。
因此，如何让ComboBox再次对所有项目调用ToString方法，而无需从ComboBox中移除所有项目并将其重新添加回来？
答案 0 :(得分：6)
感谢svick，RefreshItems（）工作，但因为它受到保护（所以只能由子类调用）我必须做
public class RefreshingComboBox : ComboBox
{
public new void RefreshItem(int index)
{
base.RefreshItem(index);
}
public new void RefreshItems()
{
base.RefreshItems();
}
}
我必须为ToolStripComboBox做同样的事情，但是因为你不能将它包含的Combro盒子类化，所以它有点难，我做了
public class RefreshingToolStripComboBox : ToolStripComboBox
{
// We do not want "fake" selectedIndex change events etc, subclass that overide the OnIndexChanged etc
// will have to check InOnCultureChanged them selfs
private bool inRefresh = false;
public bool InRefresh { get { return inRefresh; } }
public void Refresh()
{
try
{
inRefresh = true;
// This is harder then it shold be, as I can't get to the Refesh method that
// is on the embebed combro box.
//
// I am trying to get ToString recalled on all the items
int selectedIndex = SelectedIndex;
object[] items = new object[Items.Count];
Items.CopyTo(items, 0);
Items.Clear();
Items.AddRange(items);
SelectedIndex = selectedIndex;
}
finally
{
inRefresh = false;
}
}
protected override void OnSelectedIndexChanged(EventArgs e)
{
if (!inRefresh)
{
base.OnSelectedIndexChanged(e);
}
}
}
我不得不通过重写OnSelectedValueChanged，OnSelectedItemChanged和OnSelectedIndexChanged来阻止普通CombroBox的不需要的事件，因为代码与ToolStripComboBox相同，我没有在这里包含它。
答案 1 :(得分：1)
您应该可以通过调用RefreshItems()方法来执行此操作。
答案 2 :(得分：1)
svick是对的。但是，正如Ian Ringrose提到的那样，子类是必要的。 RefreshItems是System.Windows.Forms.ComboBox的受保护方法。
下面的Forms应用程序提供了一个行为示例，以及更新ComboBox的RefreshItems方法：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsApplication1
{
public class Form1 : Form
{
private List<HelloWorld> helloWorlds;
#region Form1.Designer.cs
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose( bool disposing )
{
if ( disposing && (components != null) )
{
components.Dispose();
}
base.Dispose( disposing );
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this.comboBox1 = new RefreshingComboBox();
this.comboBox2 = new RefreshingComboBox();
this.label1 = new System.Windows.Forms.Label();
this.label2 = new System.Windows.Forms.Label();
this.button1 = new System.Windows.Forms.Button();
this.button2 = new System.Windows.Forms.Button();
this.button3 = new System.Windows.Forms.Button();
this.SuspendLayout();
//
// comboBox1
//
this.comboBox1.FormattingEnabled = true;
this.comboBox1.Location = new System.Drawing.Point( 76, 12 );
this.comboBox1.Name = "comboBox1";
this.comboBox1.Size = new System.Drawing.Size( 115, 21 );
this.comboBox1.TabIndex = 0;
//
// comboBox2
//
this.comboBox2.FormattingEnabled = true;
this.comboBox2.Location = new System.Drawing.Point( 250, 12 );
this.comboBox2.Name = "comboBox2";
this.comboBox2.Size = new System.Drawing.Size( 218, 21 );
this.comboBox2.TabIndex = 1;
//
// label1
//
this.label1.AutoSize = true;
this.label1.Location = new System.Drawing.Point( 12, 15 );
this.label1.Name = "label1";
this.label1.Size = new System.Drawing.Size( 58, 13 );
this.label1.TabIndex = 2;
this.label1.Text = "Language:";
//
// label2
//
this.label2.AutoSize = true;
this.label2.Location = new System.Drawing.Point( 213, 15 );
this.label2.Name = "label2";
this.label2.Size = new System.Drawing.Size( 31, 13 );
this.label2.TabIndex = 3;
this.label2.Text = "Text:";
//
// button1
//
this.button1.Location = new System.Drawing.Point( 34, 42 );
this.button1.Name = "button1";
this.button1.Size = new System.Drawing.Size( 75, 23 );
this.button1.TabIndex = 4;
this.button1.Text = "Set All";
this.button1.UseVisualStyleBackColor = true;
this.button1.Click += new System.EventHandler( this.button1_Click );
//
// button2
//
this.button2.Location = new System.Drawing.Point( 116, 42 );
this.button2.Name = "button2";
this.button2.Size = new System.Drawing.Size( 75, 23 );
this.button2.TabIndex = 5;
this.button2.Text = "Set Random";
this.button2.UseVisualStyleBackColor = true;
this.button2.Click += new System.EventHandler( this.button2_Click );
//
// button3
//
this.button3.Location = new System.Drawing.Point( 393, 42 );
this.button3.Name = "button3";
this.button3.Size = new System.Drawing.Size( 75, 23 );
this.button3.TabIndex = 6;
this.button3.Text = "Refresh!";
this.button3.UseVisualStyleBackColor = true;
this.button3.Click += new System.EventHandler( this.button3_Click );
//
// Form1
//
this.AutoScaleDimensions = new System.Drawing.SizeF( 6F, 13F );
this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this.ClientSize = new System.Drawing.Size( 556, 77 );
this.Controls.Add( this.button3 );
this.Controls.Add( this.button2 );
this.Controls.Add( this.button1 );
this.Controls.Add( this.label2 );
this.Controls.Add( this.label1 );
this.Controls.Add( this.comboBox2 );
this.Controls.Add( this.comboBox1 );
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout( false );
this.PerformLayout();
}
#endregion
private System.Windows.Forms.ComboBox comboBox1;
private System.Windows.Forms.ComboBox comboBox2;
private System.Windows.Forms.Label label1;
private System.Windows.Forms.Label label2;
private System.Windows.Forms.Button button1;
private System.Windows.Forms.Button button2;
private System.Windows.Forms.Button button3;
#endregion
public Form1()
{
InitializeComponent();
comboBox1.DataSource = new HelloWorld().GetLanguages();
helloWorlds = new List<HelloWorld>();
while ( helloWorlds.Count < 10 )
{
helloWorlds.Add( new HelloWorld() );
}
comboBox2.DataSource = helloWorlds;
}
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault( false );
Application.Run( new Form1() );
}
private void changeAllLanguages()
{
HelloWorld.LanguageValue newLang = (HelloWorld.LanguageValue) comboBox1.SelectedValue;
helloWorlds.ForEach(
delegate( HelloWorld hw )
{
hw.Language = newLang;
} );
}
private void changeRandomLanguage()
{
int index = new Random().Next( helloWorlds.Count );
HelloWorld.LanguageValue newLang = (HelloWorld.LanguageValue) comboBox1.SelectedValue;
helloWorlds[index].Language = newLang;
}
private void button1_Click( object sender, EventArgs e )
{
changeAllLanguages();
}
private void button2_Click( object sender, EventArgs e )
{
changeRandomLanguage();
}
private void button3_Click( object sender, EventArgs e )
{
(comboBox2 as RefreshingComboBox).RefreshItems();
}
}
public class RefreshingComboBox : System.Windows.Forms.ComboBox
{
public new void RefreshItem(int index)
{
base.RefreshItem(index);
}
public new void RefreshItems()
{
base.RefreshItems();
}
}
public class HelloWorld
{
public enum LanguageValue
{
English,
日本語,
Deutsch,
Français,
Český
}
private LanguageValue language;
public LanguageValue Language
{
get
{
return language;
}
set
{
language = value;
}
}
public Array GetLanguages()
{
return Enum.GetValues( typeof( LanguageValue ) );
}
Dictionary<LanguageValue, string> helloWorlds;
public HelloWorld()
{
helloWorlds = new Dictionary<LanguageValue, string>();
helloWorlds[LanguageValue.English] = "Hello, world!";
helloWorlds[LanguageValue.日本語] = "こんにちは、世界！";
helloWorlds[LanguageValue.Deutsch] = "Hallo, Welt!";
helloWorlds[LanguageValue.Français] = "Sallut, monde!";
helloWorlds[LanguageValue.Český] = "Ahoj svět!";
}
public override string ToString()
{
return helloWorlds[language];
}
}
}
答案 3 :(得分：1)
我使用此扩展程序：
/// <summary>
/// Recreates the items
/// </summary>
public static void RefreshItems(this ComboBox cb)
{
var selectedIndex = cb.SelectedIndex;
cb.SelectedIndex = -1;
MethodInfo dynMethod = cb.GetType().GetMethod("RefreshItems", BindingFlags.NonPublic | BindingFlags.Instance);
dynMethod.Invoke(cb, null);
cb.SelectedIndex = selectedIndex;
}