ComboBox.SelectedIndexChanged イベント
SelectedIndex プロパティが変更された場合に発生します。
名前空間: System.Windows.Forms
アセンブリ: System.Windows.Forms (system.windows.forms.dll 内)
構文
解説
使用例
プラットフォーム
バージョン情報
参照
アセンブリ: System.Windows.Forms (system.windows.forms.dll 内)
構文Public Event SelectedIndexChanged As EventHandler
Dim instance As ComboBox Dim handler As EventHandler AddHandler instance.SelectedIndexChanged, handler
public event EventHandler SelectedIndexChanged
public: event EventHandler^ SelectedIndexChanged { void add (EventHandler^ value); void remove (EventHandler^ value); }
/** @event */ public void add_SelectedIndexChanged (EventHandler value) /** @event */ public void remove_SelectedIndexChanged (EventHandler value)
解説このイベントのイベント ハンドラを作成して、ComboBox 内で選択されているインデックスがいつ変更されたかを判断できます。この機能は、ComboBox 内の現在の選択項目に基づいて、他のコントロールに情報を表示する必要があるときに役立ちます。このイベントのイベント ハンドラを使用して、他のコントロールに情報を読み込むことができます。
使用例MaxDropDownItems プロパティおよび DropDownStyle プロパティを設定し、FindStringExact メソッドを使用して ComboBox を検索することによって、ComboBox コントロールを初期化するコード例を次に示します。この例はまた、SelectedIndexChanged イベントの処理方法も示しています。この例を実行するには、次のコードを TextBox1 という名前の TextBox が配置されているフォームに貼り付け、フォームのコンストラクタまたは Load イベントで InitializeComboBox メソッドを呼び出します。
' Declare comboBox1 as a ComboBox.
Friend WithEvents ComboBox1 As
System.Windows.Forms.ComboBox
' This method initializes the combo box, adding a large string
' array but limiting the drop-down size to six rows so the combo
box
' doesn't cover other controls when it expands.
Private Sub InitializeComboBox()
Me.ComboBox1 = New System.Windows.Forms.ComboBox
Dim employees() As String
= New String() {"Hamilton,
David", _
"Hensien, Kari", "Hammond,
Maria", "Harris, Keith", _
"Henshaw, Jeff D.", "Hanson,
Mark", "Harnpadoungsataya, Sariya",
_
"Harrington, Mark", "Harris,
Keith", "Hartwig, Doris", _
"Harui, Roger", "Hassall,
Mark", "Hasselberg, Jonas", _
"Harnpadoungsataya, Sariya", "Henshaw,
Jeff D.", "Henshaw, Jeff D.", _
"Hensien, Kari", "Harris,
Keith", "Henshaw, Jeff D.", _
"Hensien, Kari", "Hasselberg,
Jonas", "Harrington, Mark", _
"Hedlund, Magnus", "Hay,
Jeff", "Heidepriem, Brandon D."}
ComboBox1.Items.AddRange(employees)
Me.ComboBox1.Location = New System.Drawing.Point(136,
32)
Me.ComboBox1.MaxDropDownItems = 5
Me.ComboBox1.DropDownStyle = ComboBoxStyle.DropDown
Me.ComboBox1.Name = "ComboBox1"
Me.ComboBox1.Size = New System.Drawing.Size(136,
81)
Me.ComboBox1.TabIndex = 0
Me.Controls.Add(Me.ComboBox1)
End Sub
<br /><span space="preserve">...</span><br
/> ' This method is called when the user changes his or her
selection.
' It searches for all occurrences of the selected employee's
' name in the Items array and adds the employee's name and
' the number of occurrences to TextBox1.Text.
' CAUTION This code exposes a known bug: If the index passed to
the
' FindStringExact(searchString, index) method is the last index
' of the array, the code throws an exception.
Private Sub ComboBox1_SelectedIndexChanged(ByVal
sender As Object, _
ByVal e As System.EventArgs) Handles
ComboBox1.SelectedIndexChanged
Dim comboBox As comboBox = CType(sender,
comboBox)
' Save the selected employee's name, because we will remove
' the employee's name from the list.
Dim selectedEmployee = CType(ComboBox1.SelectedItem, String)
Dim count As Integer
= 0
Dim resultIndex As Integer
= -1
' Call the FindStringExact method to find the first
' occurrence in the list.
resultIndex = ComboBox1.FindStringExact(ComboBox1.SelectedItem)
' Remove the name as it is found, and increment the found count.
' Then call the FindStringExact method again, passing in the
index of the
' current found item so the search starts there instead of
' at the beginning of the list.
While (resultIndex <> -1)
ComboBox1.Items.RemoveAt(resultIndex)
count += 1
resultIndex = ComboBox1.FindStringExact _
(selectedEmployee, resultIndex)
End While
' Update the text in Textbox1.
TextBox1.Text = TextBox1.Text & Microsoft.VisualBasic.vbCrLf _
& selectedEmployee & ": " &
count
End Sub
// Declare comboBox1 as a ComboBox. internal System.Windows.Forms.ComboBox ComboBox1; // This method initializes the combo box, adding a large string array // but limiting the drop-down size to six rows so the combo box doesn't // cover other controls when it expands. private void InitializeComboBox() { this.ComboBox1 = new System.Windows.Forms.ComboBox(); string[] employees = new string[]{"Hamilton, David", "Hensien, Kari", "Hammond, Maria", "Harris, Keith", "Henshaw, Jeff D.", "Hanson, Mark", "Harnpadoungsataya, Sariya", "Harrington, Mark", "Harris, Keith", "Hartwig, Doris", "Harui, Roger", "Hassall, Mark", "Hasselberg, Jonas", "Harnpadoungsataya, Sariya", "Henshaw, Jeff D.", "Henshaw, Jeff D.", "Hensien, Kari", "Harris, Keith", "Henshaw, Jeff D.", "Hensien, Kari", "Hasselberg, Jonas", "Harrington, Mark", "Hedlund, Magnus", "Hay, Jeff", "Heidepriem, Brandon D."}; ComboBox1.Items.AddRange(employees); this.ComboBox1.Location = new System.Drawing.Point(136, 32); this.ComboBox1.MaxDropDownItems = 5; this.ComboBox1.DropDownStyle = ComboBoxStyle.DropDownList; this.ComboBox1.Name = "ComboBox1"; this.ComboBox1.Size = new System.Drawing.Size(136, 81); this.ComboBox1.TabIndex = 0; this.Controls.Add(this.ComboBox1); // Associate the event-handling method with the // SelectedIndexChanged event. this.ComboBox1.SelectedIndexChanged += new System.EventHandler(ComboBox1_SelectedIndexChanged); } <br /><span space="preserve">...</span><br /> // This method is called when the user changes his or her selection. // It searches for all occurrences of the selected employee's // name in the Items array and adds the employee's name and // the number of occurrences to TextBox1.Text. // CAUTION This code exposes a known bug: If the index passed to the // FindStringExact(searchString, index) method is the last index // of the array, the code throws an exception. private void ComboBox1_SelectedIndexChanged(object sender, System.EventArgs e) { ComboBox comboBox = (ComboBox) sender; // Save the selected employee's name, because we will remove // the employee's name from the list. string selectedEmployee = (string) ComboBox1.SelectedItem; int count = 0; int resultIndex = -1; // Call the FindStringExact method to find the first // occurrence in the list. resultIndex = ComboBox1.FindStringExact(selectedEmployee); // Remove the name as it is found, and increment the found count. // Then call the FindStringExact method again, passing in the // index of the current found item so the search starts there // instead of at the beginning of the list. while (resultIndex!=-1) { ComboBox1.Items.RemoveAt(resultIndex); count += 1; resultIndex = ComboBox1.FindStringExact(selectedEmployee, resultIndex); } // Update the text in Textbox1. TextBox1.Text = TextBox1.Text+ "\r\n" + selectedEmployee + ": " + count; }
// Declare comboBox1 as a ComboBox. internal: System::Windows::Forms::ComboBox^ ComboBox1; private: // This method initializes the combo box, adding a large string array // but limiting the drop-down size to six rows so the combo box doesn't // cover other controls when it expands. void InitializeComboBox() { this->ComboBox1 = gcnew System::Windows::Forms::ComboBox; array<String^>^ employees = {"Hamilton, David","Hensien, Kari", "Hammond, Maria","Harris, Keith","Henshaw, Jeff D.", "Hanson, Mark","Harnpadoungsataya, Sariya", "Harrington, Mark","Harris, Keith","Hartwig, Doris" , "Harui, Roger","Hassall, Mark","Hasselberg, Jonas" , "Harnpadoungsataya, Sariya","Henshaw, Jeff D.", "Henshaw, Jeff D.","Hensien, Kari","Harris, Keith" , "Henshaw, Jeff D.","Hensien, Kari","Hasselberg, Jonas", "Harrington, Mark","Hedlund, Magnus","Hay, Jeff" , "Heidepriem, Brandon D."}; ComboBox1->Items->AddRange( employees ); this->ComboBox1->Location = System::Drawing::Point( 136, 32 ); this->ComboBox1->MaxDropDownItems = 5; this->ComboBox1->DropDownStyle = ComboBoxStyle::DropDownList; this->ComboBox1->Name = "ComboBox1"; this->ComboBox1->Size = System::Drawing::Size( 136, 81 ); this->ComboBox1->TabIndex = 0; this->Controls->Add( this->ComboBox1 ); // Associate the event-handling method with the // SelectedIndexChanged event. this->ComboBox1->SelectedIndexChanged += gcnew System::EventHandler( this, &Form1::ComboBox1_SelectedIndexChanged ); } <br /><span space="preserve">...</span><br />private: // This method is called when the user changes his or her selection. // It searches for all occurrences of the selected employee's // name in the Items array and adds the employee's name and // the number of occurrences to TextBox1.Text. // CAUTION This code exposes a known bug: If the index passed to the // FindStringExact(searchString, index) method is the last index // of the array, the code throws an exception. void ComboBox1_SelectedIndexChanged( Object^ sender, System::EventArgs^ e ) { ComboBox^ comboBox = (ComboBox^)(sender); // Save the selected employee's name, because we will remove // the employee's name from the list. String^ selectedEmployee = (String^)(ComboBox1->SelectedItem); int count = 0; int resultIndex = -1; // Call the FindStringExact method to find the first // occurrence in the list. resultIndex = ComboBox1->FindStringExact( selectedEmployee ); // Remove the name as it is found, and increment the found count. // Then call the FindStringExact method again, passing in the // index of the current found item so the search starts there // instead of at the beginning of the list. while ( resultIndex != -1 ) { ComboBox1->Items->RemoveAt( resultIndex ); count += 1; resultIndex = ComboBox1->FindStringExact( selectedEmployee, resultIndex ); } TextBox1->Text = TextBox1->Text + "\r\n" + selectedEmployee + ": " + count; }
// Declare comboBox1 as a ComboBox. System.Windows.Forms.ComboBox comboBox1; // This method initializes the combo box, adding a large string array // but limiting the drop-down size to six rows so the combo box doesn't // cover other controls when it expands. private void InitializeComboBox() { this.comboBox1 = new System.Windows.Forms.ComboBox(); String employees[] = new String[] { "Hamilton, David", "Hensien, Kari", "Hammond, Maria", "Harris, Keith", "Henshaw, Jeff D.", "Hanson, Mark", "Harnpadoungsataya, Sariya", "Harrington, Mark", "Harris, Keith", "Hartwig, Doris", "Harui, Roger", "Hassall, Mark", "Hasselberg, Jonas", "Harnpadoungsataya, Sariya", "Henshaw, Jeff D.","Henshaw, Jeff D.", "Hensien, Kari", "Harris, Keith", "Henshaw, Jeff D.", "Hensien, Kari", "Hasselberg, Jonas", "Harrington, Mark", "Hedlund, Magnus", "Hay, Jeff", "Heidepriem, Brandon D." }; comboBox1.get_Items().AddRange(employees); this.comboBox1.set_Location(new System.Drawing.Point(136, 32)); this.comboBox1.set_MaxDropDownItems(5); this.comboBox1.set_DropDownStyle(ComboBoxStyle.DropDownList); this.comboBox1.set_Name("comboBox1"); this.comboBox1.set_Size(new System.Drawing.Size(136, 81)); this.comboBox1.set_TabIndex(0); this.get_Controls().Add(this.comboBox1); // Associate the event-handling method with the // SelectedIndexChanged event. this.comboBox1.add_SelectedIndexChanged(new System.EventHandler( comboBox1_SelectedIndexChanged)); } //InitializeComboBox <br /><span space="preserve">...</span><br /> // This method is called when the user changes his or her selection. // It searches for all occurrences of the selected employee's // name in the Items array and adds the employee's name and // the number of occurrences to textBox1.Text. // CAUTION This code exposes a known bug: If the index passed to the // FindStringExact(searchString, index) method is the last index // of the array, the code throws an exception. private void comboBox1_SelectedIndexChanged(Object sender, System.EventArgs e) { ComboBox comboBox = (ComboBox)sender; // Save the selected employee's name, because we will remove // the employee's name from the list. String selectedEmployee = (String)(comboBox1.get_SelectedItem()); int count = 0; int resultIndex = -1; // Call the FindStringExact method to find the first // occurrence in the list. resultIndex = comboBox1.FindStringExact(selectedEmployee); // Remove the name as it is found, and increment the found count. // Then call the FindStringExact method again, passing in the // index of the current found item so the search starts there // instead of at the beginning of the list. while (resultIndex != -1) { comboBox1.get_Items().RemoveAt(resultIndex); count += 1; resultIndex = comboBox1.FindStringExact(selectedEmployee, resultIndex); } // Update the text in textBox1. textBox1.set_Text(textBox1.get_Text() + "\r\n" + selectedEmployee + ": " + count); } //comboBox1_SelectedIndexChanged
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