DomainUpDown.OnSelectedItemChanged(Object, EventArgs) 方法

定義

命名空間:

System.Windows.Forms

組件:

System.Windows.Forms.dll

引發 SelectedItemChanged 事件。

protected:
 void OnSelectedItemChanged(System::Object ^ source, EventArgs ^ e);

protected void OnSelectedItemChanged (object? source, EventArgs e);

member this.OnSelectedItemChanged : obj * EventArgs -> unit

Protected Sub OnSelectedItemChanged (source As Object, e As EventArgs)

參數

source

Object

事件的來源。

e

EventArgs

包含事件資料的 EventArgs。

範例

下列程式碼範例會建立並初始化 DomainUpDown 控制項。 此範例可讓您設定部分屬性，並建立字串集合，以顯示在微調方塊中 (也稱為上下按鈕控制項) 。 程式碼假設 TextBoxCheckBox 、 和 Button 已在表單上具現化。 此範例也假設您在類別層級宣告為名為 myCounter 的 32 位帶正負號整數的成員變數。 您可以在文字方塊中輸入字串，並在按一下按鈕時將其新增至 Items 集合。 按一下核取方塊，您可以切換 屬性， Sorted 並觀察微調方塊中專案集合的差異。

protected:
   DomainUpDown^ domainUpDown1;

private:
   void MySub()
   {
      // Create and initialize the DomainUpDown control.
      domainUpDown1 = gcnew System::Windows::Forms::DomainUpDown;
      
      // Add the DomainUpDown control to the form.
      Controls->Add( domainUpDown1 );
   }

   void button1_Click( System::Object^ sender,
     System::EventArgs^ e )
   {
      // Add the text box contents and initial location in the collection
      // to the DomainUpDown control.
      domainUpDown1->Items->Add( String::Concat(
         (textBox1->Text->Trim()), " - ", myCounter.ToString() ) );
      
      // Increment the counter variable.
      myCounter = myCounter + 1;
      
      // Clear the TextBox.
      textBox1->Text = "";
   }

   void checkBox1_Click( Object^ sender, EventArgs^ e )
   {
      // If Sorted is set to true, set it to false; 
      // otherwise set it to true.
      if ( domainUpDown1->Sorted )
      {
         domainUpDown1->Sorted = false;
      }
      else
      {
         domainUpDown1->Sorted = true;
      }
   }

   void domainUpDown1_SelectedItemChanged( Object^ sender, EventArgs^ e )
   {
      // Display the SelectedIndex and SelectedItem property values in a MessageBox.
      MessageBox::Show( String::Concat( "SelectedIndex: ",
      domainUpDown1->SelectedIndex.ToString(), "\n", "SelectedItem: ",
      domainUpDown1->SelectedItem->ToString() ) );
   }

protected DomainUpDown domainUpDown1;

private void MySub()
 {
    // Create and initialize the DomainUpDown control.
    domainUpDown1 = new System.Windows.Forms.DomainUpDown();
    
    // Add the DomainUpDown control to the form.
    Controls.Add(domainUpDown1);
 }
 
 private void button1_Click(System.Object sender, 
                           System.EventArgs e)
 {   
    // Add the text box contents and initial location in the collection
    // to the DomainUpDown control.
    domainUpDown1.Items.Add((textBox1.Text.Trim()) + " - " + myCounter);
    
    // Increment the counter variable.
    myCounter = myCounter + 1;
 
    // Clear the TextBox.
    textBox1.Text = "";
 }
 
 private void checkBox1_Click(System.Object sender, 
                             System.EventArgs e)
 {
    // If Sorted is set to true, set it to false; 
    // otherwise set it to true.
    if (domainUpDown1.Sorted)
    {
       domainUpDown1.Sorted = false;
    }
    else
    {
       domainUpDown1.Sorted = true;
    }
 }
 
 private void domainUpDown1_SelectedItemChanged(System.Object sender, 
                                               System.EventArgs e)
 {
    // Display the SelectedIndex and SelectedItem property values in a MessageBox.
    MessageBox.Show("SelectedIndex: " + domainUpDown1.SelectedIndex.ToString() 
       + "\n" + "SelectedItem: " + domainUpDown1.SelectedItem.ToString());
 }

Protected domainUpDown1 As DomainUpDown


Private Sub MySub()
    ' Create and initialize the DomainUpDown control.
    domainUpDown1 = New System.Windows.Forms.DomainUpDown()
    
    ' Add the DomainUpDown control to the form.
    Controls.Add(domainUpDown1)
End Sub


Private Sub button1_Click(sender As System.Object, e As System.EventArgs)
    ' Add the text box contents and initial location in the collection
    ' to the DomainUpDown control.
    domainUpDown1.Items.Add((textBox1.Text.Trim() & " - " & myCounter))
    
    ' Increment the counter variable.
    myCounter = myCounter + 1
    
    ' Clear the TextBox.
    textBox1.Text = ""
End Sub


Private Sub checkBox1_Click(sender As System.Object, e As System.EventArgs)
    ' If Sorted is set to true, set it to false; 
    ' otherwise set it to true.
    If domainUpDown1.Sorted Then
        domainUpDown1.Sorted = False
    Else
        domainUpDown1.Sorted = True
    End If
End Sub


Private Sub domainUpDown1_SelectedItemChanged _
    (sender As System.Object, e As System.EventArgs)
    
    ' Display the SelectedIndex and SelectedItem property values in a MessageBox.
    MessageBox.Show(("SelectedIndex: " & domainUpDown1.SelectedIndex.ToString() & _
        ControlChars.Cr & "SelectedItem: " & domainUpDown1.SelectedItem.ToString()))
End Sub

備註

引發事件會透過委派叫用此事件處理常式。 如需詳細資訊，請參閱 處理和引發事件。

OnSelectedItemChanged 方法也允許衍生類別處理事件，而不用附加委派。 這是在衍生類別中處理事件的慣用技巧。

給繼承者的注意事項

在 OnSelectedItemChanged(Object, EventArgs) 衍生類別中覆寫時，請務必呼叫基類的 OnSelectedItemChanged(Object, EventArgs) 方法，讓已註冊的委派接收事件。

另請參閱

• SelectedItem
• SelectedItemChanged