ComboBox 类 (System.Windows.Forms) | Microsoft Learn

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public ref class ComboBox : System::Windows::Forms::ListControl

public class ComboBox : System.Windows.Forms.ListControl

[System.ComponentModel.DefaultBindingProperty("Text")]
[System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.AutoDispatch)]
[System.Runtime.InteropServices.ComVisible(true)]
public class ComboBox : System.Windows.Forms.ListControl

[System.ComponentModel.DefaultBindingProperty("Text")]
public class ComboBox : System.Windows.Forms.ListControl

type ComboBox = class
    inherit ListControl

[<System.ComponentModel.DefaultBindingProperty("Text")>]
[<System.Runtime.InteropServices.ClassInterface(System.Runtime.InteropServices.ClassInterfaceType.AutoDispatch)>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type ComboBox = class
    inherit ListControl

[<System.ComponentModel.DefaultBindingProperty("Text")>]
type ComboBox = class
    inherit ListControl

Public Class ComboBox
Inherits ListControl

Object

MarshalByRefObject

Component

Control

ListControl

ComboBox

下面的代码示例是一个完整的应用程序，演示如何使用 Add 该方法向 a ComboBox 添加项、 FindString 查找项的方法 BeginUpdate ComboBox 以及有效向 a ComboBox 添加大量项的方法和 EndUpdate 方法。存储不同于显示文本的值的功能继承自 ListControl 。有关如何使用此功能的示例，请参阅 ListControl 类。

必须添加对命名空间的 System.Drawing``System.Windows.Forms 引用才能运行此示例。


   #using <System.dll>
#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>
using namespace System;
using namespace System::Windows::Forms;
namespace Win32Form1Namespace
   public ref class Win32Form1: public System::Windows::Forms::Form
   private:
      System::Windows::Forms::Button^ addButton;
      System::Windows::Forms::TextBox^ textBox2;
      System::Windows::Forms::Button^ addGrandButton;
      System::Windows::Forms::ComboBox^ comboBox1;
      System::Windows::Forms::Button^ showSelectedButton;
      System::Windows::Forms::TextBox^ textBox1;
      System::Windows::Forms::Button^ findButton;
      System::Windows::Forms::Label ^ label1;
   public:
      Win32Form1()
         this->InitializeComponent();
   private:
      void InitializeComponent()
         this->addButton = gcnew System::Windows::Forms::Button;
         this->textBox2 = gcnew System::Windows::Forms::TextBox;
         this->addGrandButton = gcnew System::Windows::Forms::Button;
         this->comboBox1 = gcnew System::Windows::Forms::ComboBox;
         this->showSelectedButton = gcnew System::Windows::Forms::Button;
         this->textBox1 = gcnew System::Windows::Forms::TextBox;
         this->findButton = gcnew System::Windows::Forms::Button;
         this->label1 = gcnew System::Windows::Forms::Label;
         this->addButton->Location = System::Drawing::Point( 248, 32 );
         this->addButton->Size = System::Drawing::Size( 40, 24 );
         this->addButton->TabIndex = 1;
         this->addButton->Text = "Add";
         this->addButton->Click += gcnew System::EventHandler(
            this, &Win32Form1::addButton_Click );
         this->textBox2->Location = System::Drawing::Point( 8, 64 );
         this->textBox2->Size = System::Drawing::Size( 232, 20 );
         this->textBox2->TabIndex = 6;
         this->textBox2->Text = "";
         this->addGrandButton->Location = System::Drawing::Point( 8, 96 );
         this->addGrandButton->Size = System::Drawing::Size( 280, 23 );
         this->addGrandButton->TabIndex = 2;
         this->addGrandButton->Text = "Add 1, 000 Items";
         this->addGrandButton->Click += gcnew System::EventHandler(
            this, &Win32Form1::addGrandButton_Click );
         this->comboBox1->Anchor = (System::Windows::Forms::AnchorStyles)(
            (System::Windows::Forms::AnchorStyles::Bottom | System::Windows::Forms::AnchorStyles::Left) |
             System::Windows::Forms::AnchorStyles::Right);
         this->comboBox1->DropDownWidth = 280;
         array<Object^>^ objectArray = {"Item 1",
            "Item 2",
            "Item 3",
            "Item 4",
            "Item 5"};
         this->comboBox1->Items->AddRange( objectArray );
         this->comboBox1->Location = System::Drawing::Point( 8, 248 );
         this->comboBox1->Size = System::Drawing::Size( 280, 21 );
         this->comboBox1->TabIndex = 7;
         this->showSelectedButton->Location = System::Drawing::Point( 8, 128 );
         this->showSelectedButton->Size = System::Drawing::Size( 280, 24 );
         this->showSelectedButton->TabIndex = 4;
         this->showSelectedButton->Text = "What Item is Selected?";
         this->showSelectedButton->Click += gcnew System::EventHandler( 
            this, &Win32Form1::showSelectedButton_Click );
         this->textBox1->Location = System::Drawing::Point( 8, 32 );
         this->textBox1->Size = System::Drawing::Size( 232, 20 );
         this->textBox1->TabIndex = 5;
         this->textBox1->Text = "";
         this->findButton->Location = System::Drawing::Point( 248, 64 );
         this->findButton->Size = System::Drawing::Size( 40, 24 );
         this->findButton->TabIndex = 3;
         this->findButton->Text = "Find";
         this->findButton->Click += gcnew System::EventHandler( 
            this, &Win32Form1::findButton_Click );
         this->label1->Location = System::Drawing::Point( 8, 224 );
         this->label1->Size = System::Drawing::Size( 144, 23 );
         this->label1->TabIndex = 0;
         this->label1->Text = "Test ComboBox";
         this->ClientSize = System::Drawing::Size( 292, 273 );
         array<System::Windows::Forms::Control^>^ controlsArray = {this->comboBox1,
            this->textBox2,
            this->textBox1,
            this->showSelectedButton,
            this->findButton,
            this->addGrandButton,
            this->addButton,
            this->label1};
         this->Controls->AddRange( controlsArray );
         this->Text = "ComboBox Sample";
      void addButton_Click( Object^ sender, System::EventArgs^ e )
         comboBox1->Items->Add( textBox1->Text );
      void addGrandButton_Click( Object^ sender, System::EventArgs^ e )
         comboBox1->BeginUpdate();
         for ( int i = 0; i < 1000; i++ )
            comboBox1->Items->Add( "Item 1 " + i.ToString() );
         comboBox1->EndUpdate();
      void findButton_Click( Object^ sender, System::EventArgs^ e )
         int index = comboBox1->FindString( textBox2->Text );
         comboBox1->SelectedIndex = index;
      void showSelectedButton_Click( Object^ sender, System::EventArgs^ e )
         int selectedIndex = comboBox1->SelectedIndex;
         Object^ selectedItem = comboBox1->SelectedItem;
         MessageBox::Show( "Selected Item Text: " + selectedItem->ToString() + "\n" +
            "Index: " + selectedIndex.ToString() );
[System::STAThreadAttribute]
int main()
   System::Windows::Forms::Application::Run( gcnew Win32Form1Namespace::Win32Form1 );
   
    using System;
using System.Windows.Forms;
namespace Win32Form1Namespace {
    public class Win32Form1 : System.Windows.Forms.Form {
        private System.Windows.Forms.Button addButton;
        private System.Windows.Forms.TextBox textBox2;
        private System.Windows.Forms.Button addGrandButton;
        private System.Windows.Forms.ComboBox comboBox1;
        private System.Windows.Forms.Button showSelectedButton;
        private System.Windows.Forms.TextBox textBox1;
        private System.Windows.Forms.Button findButton;
        private System.Windows.Forms.Label label1;
        public Win32Form1() {
            this.InitializeComponent();
        [System.STAThreadAttribute()]
        public static void Main() {
            System.Windows.Forms.Application.Run(new Win32Form1());
        private void InitializeComponent() {
            this.addButton = new System.Windows.Forms.Button();
            this.textBox2 = new System.Windows.Forms.TextBox();
            this.addGrandButton = new System.Windows.Forms.Button();
            this.comboBox1 = new System.Windows.Forms.ComboBox();
            this.showSelectedButton = new System.Windows.Forms.Button();
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.findButton = new System.Windows.Forms.Button();
            this.label1 = new System.Windows.Forms.Label();
            this.addButton.Location = new System.Drawing.Point(248, 32);
            this.addButton.Size = new System.Drawing.Size(40, 24);
            this.addButton.TabIndex = 1;
            this.addButton.Text = "Add";
            this.addButton.Click += new System.EventHandler(this.addButton_Click);
            this.textBox2.Location = new System.Drawing.Point(8, 64);
            this.textBox2.Size = new System.Drawing.Size(232, 20);
            this.textBox2.TabIndex = 6;
            this.textBox2.Text = "";
            this.addGrandButton.Location = new System.Drawing.Point(8, 96);
            this.addGrandButton.Size = new System.Drawing.Size(280, 23);
            this.addGrandButton.TabIndex = 2;
            this.addGrandButton.Text = "Add 1,000 Items";
            this.addGrandButton.Click += new System.EventHandler(this.addGrandButton_Click);
            this.comboBox1.Anchor = ((System.Windows.Forms.AnchorStyles.Bottom | System.Windows.Forms.AnchorStyles.Left) 
                        | System.Windows.Forms.AnchorStyles.Right);
            this.comboBox1.DropDownWidth = 280;
            this.comboBox1.Items.AddRange(new object[] {"Item 1",
                        "Item 2",
                        "Item 3",
                        "Item 4",
                        "Item 5"});
            this.comboBox1.Location = new System.Drawing.Point(8, 248);
            this.comboBox1.Size = new System.Drawing.Size(280, 21);
            this.comboBox1.TabIndex = 7;
            this.showSelectedButton.Location = new System.Drawing.Point(8, 128);
            this.showSelectedButton.Size = new System.Drawing.Size(280, 24);
            this.showSelectedButton.TabIndex = 4;
            this.showSelectedButton.Text = "What Item is Selected?";
            this.showSelectedButton.Click += new System.EventHandler(this.showSelectedButton_Click);
            this.textBox1.Location = new System.Drawing.Point(8, 32);
            this.textBox1.Size = new System.Drawing.Size(232, 20);
            this.textBox1.TabIndex = 5;
            this.textBox1.Text = "";
            this.findButton.Location = new System.Drawing.Point(248, 64);
            this.findButton.Size = new System.Drawing.Size(40, 24);
            this.findButton.TabIndex = 3;
            this.findButton.Text = "Find";
            this.findButton.Click += new System.EventHandler(this.findButton_Click);
            this.label1.Location = new System.Drawing.Point(8, 224);
            this.label1.Size = new System.Drawing.Size(144, 23);
            this.label1.TabIndex = 0;
            this.label1.Text = "Test ComboBox";
            this.ClientSize = new System.Drawing.Size(292, 273);
            this.Controls.AddRange(new System.Windows.Forms.Control[] {this.comboBox1,
                        this.textBox2,
                        this.textBox1,
                        this.showSelectedButton,
                        this.findButton,
                        this.addGrandButton,
                        this.addButton,
                        this.label1});
            this.Text = "ComboBox Sample";
        private void addButton_Click(object sender, System.EventArgs e) {
           comboBox1.Items.Add(textBox1.Text);
        private void addGrandButton_Click(object sender, System.EventArgs e) {
            comboBox1.BeginUpdate();
            for (int i = 0; i < 1000; i++) {
                comboBox1.Items.Add("Item 1" + i.ToString());
            comboBox1.EndUpdate();
        private void findButton_Click(object sender, System.EventArgs e) {
            int index = comboBox1.FindString(textBox2.Text);
            comboBox1.SelectedIndex = index;
        private void showSelectedButton_Click(object sender, System.EventArgs e) {
            int selectedIndex = comboBox1.SelectedIndex;
            Object selectedItem = comboBox1.SelectedItem;
            MessageBox.Show("Selected Item Text: " + selectedItem.ToString() + "\n" +
                            "Index: " + selectedIndex.ToString());
    
     Imports System.Windows.Forms
Namespace ComboBoxSampleNamespace
    Public Class ComboBoxSample
        Inherits System.Windows.Forms.Form
        Private addButton As System.Windows.Forms.Button
        Private textBox2 As System.Windows.Forms.TextBox
        Private addGrandButton As System.Windows.Forms.Button
        Private comboBox1 As System.Windows.Forms.ComboBox
        Private showSelectedButton As System.Windows.Forms.Button
        Private textBox1 As System.Windows.Forms.TextBox
        Private findButton As System.Windows.Forms.Button
        Private label1 As System.Windows.Forms.Label
        Public Sub New()
            MyBase.New()
            Me.InitializeComponent()
        End Sub
        <System.STAThreadAttribute()> Public Shared Sub Main()
            System.Windows.Forms.Application.Run(New ComboBoxSample())
        End Sub
        Private Sub InitializeComponent()
            Me.addButton = New System.Windows.Forms.Button()
            Me.textBox2 = New System.Windows.Forms.TextBox()
            Me.addGrandButton = New System.Windows.Forms.Button()
            Me.comboBox1 = New System.Windows.Forms.ComboBox()
            Me.showSelectedButton = New System.Windows.Forms.Button()
            Me.textBox1 = New System.Windows.Forms.TextBox()
            Me.findButton = New System.Windows.Forms.Button()
            Me.label1 = New System.Windows.Forms.Label()
            Me.addButton.Location = New System.Drawing.Point(248, 32)
            Me.addButton.Size = New System.Drawing.Size(40, 24)
            Me.addButton.TabIndex = 1
            Me.addButton.Text = "Add"
            AddHandler Me.addButton.Click, AddressOf Me.addButton_Click
            Me.textBox2.Location = New System.Drawing.Point(8, 64)
            Me.textBox2.Size = New System.Drawing.Size(232, 20)
            Me.textBox2.TabIndex = 6
            Me.textBox2.Text = ""
            Me.addGrandButton.Location = New System.Drawing.Point(8, 96)
            Me.addGrandButton.Size = New System.Drawing.Size(280, 23)
            Me.addGrandButton.TabIndex = 2
            Me.addGrandButton.Text = "Add 1,000 Items"
            AddHandler Me.addGrandButton.Click, AddressOf Me.addGrandButton_Click
            Me.comboBox1.Anchor = ((System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left) _
                        Or System.Windows.Forms.AnchorStyles.Right)
            Me.comboBox1.DropDownWidth = 280
            Me.comboBox1.Items.AddRange(New Object() {"Item 1", "Item 2", "Item 3", "Item 4", "Item 5"})
            Me.comboBox1.Location = New System.Drawing.Point(8, 248)
            Me.comboBox1.Size = New System.Drawing.Size(280, 21)
            Me.comboBox1.TabIndex = 7
            Me.showSelectedButton.Location = New System.Drawing.Point(8, 128)
            Me.showSelectedButton.Size = New System.Drawing.Size(280, 24)
            Me.showSelectedButton.TabIndex = 4
            Me.showSelectedButton.Text = "What Item is Selected?"
            AddHandler Me.showSelectedButton.Click, AddressOf Me.showSelectedButton_Click
            Me.textBox1.Location = New System.Drawing.Point(8, 32)
            Me.textBox1.Size = New System.Drawing.Size(232, 20)
            Me.textBox1.TabIndex = 5
            Me.textBox1.Text = ""
            Me.findButton.Location = New System.Drawing.Point(248, 64)
            Me.findButton.Size = New System.Drawing.Size(40, 24)
            Me.findButton.TabIndex = 3
            Me.findButton.Text = "Find"
            AddHandler Me.findButton.Click, AddressOf Me.findButton_Click
            Me.label1.Location = New System.Drawing.Point(8, 224)
            Me.label1.Size = New System.Drawing.Size(144, 23)
            Me.label1.TabIndex = 0
            Me.label1.Text = "Test ComboBox"
            Me.ClientSize = New System.Drawing.Size(292, 273)
            Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.comboBox1, Me.textBox2, Me.textBox1, Me.showSelectedButton, Me.findButton, Me.addGrandButton, Me.addButton, Me.label1})
            Me.Text = "ComboBox Sample"
        End Sub
        Private Sub addButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
            comboBox1.Items.Add(textBox1.Text)
        End Sub
        Private Sub findButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
            Dim index As Integer
            index = comboBox1.FindString(textBox2.Text)
            comboBox1.SelectedIndex = index
        End Sub
        Private Sub addGrandButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
            comboBox1.BeginUpdate()
            Dim I As Integer
            For I = 0 To 1000
                comboBox1.Items.Add("Item 1" + i.ToString())
            comboBox1.EndUpdate()
        End Sub
        Private Sub showSelectedButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
            Dim selectedIndex As Integer
            selectedIndex = comboBox1.SelectedIndex
            Dim selectedItem As Object
            selectedItem = comboBox1.SelectedItem
            MessageBox.Show("Selected Item Text: " & selectedItem.ToString() & Microsoft.VisualBasic.Constants.vbCrLf & _
                                "Index: " & selectedIndex.ToString())
        End Sub
    End Class
End Namespace
     
      显示
      
       ComboBox
      
      与 a
      
       ListBox
      
      组合的文本框，使用户能够从列表中选择项目或输入新值。
     
     
      该
      
       DropDownStyle
      
      属性指定列表是始终显示还是列表是否显示在下拉列表中。 该
      
       DropDownStyle
      
      属性还指定是否可以编辑文本部分。 请参阅
      
       ComboBoxStyle
      
      可用设置及其效果。 没有设置始终显示列表，不允许输入新值。 若要显示无法添加新值的列表，请使用
      
       ListBox
      
      控件。
     
     
      若要在运行时添加或删除列表中的对象，请使用类的方法
      
       ComboBox.ObjectCollection
      
      (通过
      
       Items
      
      ) 的属性
      
       ComboBox
      
      。 可以使用该方法分配对象引用
      
       AddRange
      
      数组。 然后，该列表显示每个对象的默认字符串值。 可以使用该方法添加单个对象
      
       Add
      
      。 可以使用该方法删除项
      
       Remove
      
      ，或使用该方法清除整个列表
      
       Clear
      
      。
     
     
      除了显示和选择功能外，还提供了一种功能，
      
       ComboBox
      
      使你能够有效地将项添加到
      
       ComboBox
      
      列表的项中并查找文本。
      
       BeginUpdate
      
      使用和
      
       EndUpdate
      
      方法，可以在每次将项添加到列表中时，将大量项
      
       ComboBox
      
      添加到控件中，而无需重新绘制控件。 使用
      
       FindString
      
      和
      
       FindStringExact
      
      方法可以搜索列表中包含特定搜索字符串的项。
     
     
      可以使用这些属性来管理列表中当前选定的项、用于指定在编辑字段中显示的字符串的属性、
      
       Text
      
      
       SelectedIndex
      
      要获取或设置当前项的属性以及
      
       SelectedItem
      
      用于获取或设置对对象的引用的属性。
     
     
      如果你有一个
      
       ListBox
      
      或
      
       ComboBox
      
      
       CheckedListBox
      
      基于Windows 窗体页，并且想要修改派生窗体中这些控件的字符串集合，则基窗体中这些控件的字符串集合必须为空。 如果字符串集合不为空，则当派生另一个窗体时，它们将变为只读。