Control.CausesValidationChanged 事件

当 CausesValidation 属性的值更改时发生。

**命名空间:**System.Windows.Forms
**程序集:**System.Windows.Forms（在 system.windows.forms.dll 中）

语法

声明
Public Event CausesValidationChanged As EventHandler
用法
Dim instance As Control
Dim handler As EventHandler

AddHandler instance.CausesValidationChanged, handler

public event EventHandler CausesValidationChanged

public:
event EventHandler^ CausesValidationChanged {
    void add (EventHandler^ value);
    void remove (EventHandler^ value);
}

/** @event */
public void add_CausesValidationChanged (EventHandler value)

/** @event */
public void remove_CausesValidationChanged (EventHandler value)

JScript 支持使用事件，但不支持进行新的声明。

备注

如果通过编程修改或用户交互更改 CausesValidation 属性，则将引发此事件。

有关处理事件的更多信息，请参见 使用事件。

示例

下面的代码示例创建一个 Windows 窗体，该窗体添加在文本框中输入的数字。在显示结果之前会先验证文本框。

Private Sub AddHandlers()
    ' Add the Validating and Validated handlers for textboxes.
    AddHandler myTextBox1.Validating, AddressOf myTextBox1_Validating
    AddHandler myTextBox1.Validated, AddressOf myTextBox1_Validated
    AddHandler myTextBox2.Validating, AddressOf myTextBox2_Validating
    AddHandler myTextBox2.Validated, AddressOf myTextBox2_Validated
    AddHandler myTextBox1.CausesValidationChanged, AddressOf myTextBox1_CausesValidationChanged
    AddHandler myTextBox2.CausesValidationChanged, AddressOf myTextBox2_CausesValidationChanged
    If myTextBox1.CausesValidation = True And myTextBox2.CausesValidation = True Then
       button1.Text = "Disable Validation"
       myLabel.Text = "Validation Enabled"
       Me.Focus()
    End If
End Sub 'AddHandlers
 
Private Sub myTextBox1_Validating(sender As Object, e As System.ComponentModel.CancelEventArgs)
    If Not CheckIfTextBoxNumeric(myTextBox1) Then
       myLabel.Text = "Has to be numeric"
       e.Cancel = True
    End If
End Sub 'myTextBox1_Validating
 
Private Sub myTextBox1_Validated(sender As Object, e As System.EventArgs)
    myLabel.Text = "Validated first control"
End Sub 'myTextBox1_Validated
 
Private Sub myTextBox2_Validating(sender As Object, e As System.ComponentModel.CancelEventArgs)
    If Not CheckIfTextBoxNumeric(myTextBox2) Then
       myLabel.Text = "Has to be numeric"
       e.Cancel = True
    End If
End Sub 'myTextBox2_Validating
 
Private Sub myTextBox2_Validated(sender As Object, e As System.EventArgs)
    myLabel.Text = "Validated second control"
End Sub 'myTextBox2_Validated
 
Private Sub myTextBox1_CausesValidationChanged(sender As Object, e As System.EventArgs)
    myLabel.Text = "CausesValidation property was changed for First Textbox"
End Sub 'myTextBox1_CausesValidationChanged
 
Private Sub myTextBox2_CausesValidationChanged(sender As Object, e As System.EventArgs)
    myLabel.Text = "CausesValidation property was changed for Second Textbox"
End Sub 'myTextBox2_CausesValidationChanged
 
Private Function CheckIfTextBoxNumeric(myTextBox1 As TextBox) As Boolean
    Dim isValid As Boolean = True
    If myTextBox1.Text = "" Then
       isValid = False
    Else
       Dim i As Integer
       For i = 0 To myTextBox1.Text.Length - 1
          If Not IsNumeric(myTextBox1.Text) Then
             myTextBox1.Text = ""
             isValid = False
             Exit For
          End If
       Next i
    End If
    Return isValid
End Function 'CheckIfTextBoxNumeric
 
Private Sub myButtonAdd_Click(sender As Object, e As System.EventArgs) Handles myButtonAdd.Click
   Try
      Dim result As Integer = Convert.ToInt32(myTextBox1.Text) + Convert.ToInt32(myTextBox2.Text)
       myLabel.Text = result.ToString()
    Catch myException As Exception
       myLabel.Text = "Exception : " + myException.Message
    End Try
End Sub 'myButtonAdd_Click
 
 
Private Sub button1_Click(sender As Object, e As System.EventArgs) Handles button1.Click
    If myTextBox1.CausesValidation = False And myTextBox2.CausesValidation = False Then
       myTextBox1.CausesValidation = True
       myTextBox2.CausesValidation = True
       button1.Text = "Disable Validation"
       myLabel.Text = "Validation Enabled"
    Else
       If myTextBox1.CausesValidation = True And myTextBox2.CausesValidation = True Then
          myTextBox1.CausesValidation = False
          myTextBox2.CausesValidation = False
          button1.Text = "Enable Validation"
          myLabel.Text = "Validation Disabled"
       End If
    End If
End Sub 'button1_Click 

private void AddHandlers()
{
   // Add the Validating and Validated handlers for textboxes.
   myTextBox1.Validating +=
      new System.ComponentModel.CancelEventHandler(myTextBox1_Validating);
   myTextBox1.Validated += 
      new System.EventHandler(myTextBox1_Validated);
   myTextBox2.Validating += 
      new System.ComponentModel.CancelEventHandler(myTextBox2_Validating);
   myTextBox2.Validated += 
      new System.EventHandler(myTextBox2_Validated);
   myTextBox1.CausesValidationChanged += 
      new System.EventHandler(myTextBox1_CausesValidationChanged);
   myTextBox2.CausesValidationChanged += 
      new System.EventHandler(myTextBox2_CausesValidationChanged);
   if(myTextBox1.CausesValidation == true && myTextBox2.CausesValidation == true) 
   {
      button1.Text = "Disable Validation";
      myLabel.Text = "Validation Enabled"; 
      this.Focus(); 
   }
}
private void myTextBox1_Validating(object sender,System.ComponentModel.CancelEventArgs e)
{        
   if(!CheckIfTextBoxNumeric(myTextBox1))
   {
      myLabel.Text =  "Has to be numeric";
      e.Cancel = true;
   }
}
private void myTextBox1_Validated(object sender,System.EventArgs e)
{
   myLabel.Text = "Validated first control";          
}
private void myTextBox2_Validating(object sender,System.ComponentModel.CancelEventArgs e)
{
   if(!CheckIfTextBoxNumeric(myTextBox2))
   {
      myLabel.Text =  "Has to be numeric";
      e.Cancel = true;
   }
}
private void myTextBox2_Validated(object sender,System.EventArgs e)
{
   myLabel.Text = "Validated second control";
}
private void myTextBox1_CausesValidationChanged(object sender,System.EventArgs e)
{  
   myLabel.Text = "CausesValidation property was changed for First Textbox";
}
private void myTextBox2_CausesValidationChanged(object sender,System.EventArgs e)
{  
   myLabel.Text = "CausesValidation property was changed for Second Textbox";
}
private bool CheckIfTextBoxNumeric(TextBox myTextBox1)
{ 
   bool isValid = true;
   if(myTextBox1.Text == "")
   {
      isValid = false;
   }
   else
   {
      for(int i=0; i< myTextBox1.Text.Length;i++)
      {
         if(!(System.Char.IsNumber(myTextBox1.Text[i]))) 
         {
            myTextBox1.Text = ""; 
            isValid = false;
            break;
         }
      }
   }
   return isValid;
}
private void myButtonAdd_Click(object sender, System.EventArgs e)
{  
   try
   {
      int result = Convert.ToInt32(myTextBox1.Text) + Convert.ToInt32(myTextBox2.Text);
      myLabel.Text =  result.ToString();
   }
   catch(Exception myException)
   {
      myLabel.Text = "Exception : " + myException.Message;
   }
}

private void button1_Click(object sender, System.EventArgs e)
{  
   if(myTextBox1.CausesValidation == false && myTextBox2.CausesValidation == false) 
   {
      myTextBox1.CausesValidation = true;
      myTextBox2.CausesValidation = true;
      button1.Text = "Disable Validation"; 
      myLabel.Text = "Validation Enabled"; 
   }
   else if(myTextBox1.CausesValidation == true && myTextBox2.CausesValidation == true) 
   {
      myTextBox1.CausesValidation = false;
      myTextBox2.CausesValidation = false;
      button1.Text = "Enable Validation"; 
      myLabel.Text = "Validation Disabled"; 
   }
}

private:
   void AddHandlers()
   {
      
      // Add the Validating and Validated handlers for textboxes.
      myTextBox1->Validating += gcnew System::ComponentModel::CancelEventHandler( this, &Form1::myTextBox1_Validating );
      myTextBox1->Validated += gcnew System::EventHandler( this, &Form1::myTextBox1_Validated );
      myTextBox2->Validating += gcnew System::ComponentModel::CancelEventHandler( this, &Form1::myTextBox2_Validating );
      myTextBox2->Validated += gcnew System::EventHandler( this, &Form1::myTextBox2_Validated );
      myTextBox1->CausesValidationChanged += gcnew System::EventHandler( this, &Form1::myTextBox1_CausesValidationChanged );
      myTextBox2->CausesValidationChanged += gcnew System::EventHandler( this, &Form1::myTextBox2_CausesValidationChanged );
      if ( myTextBox1->CausesValidation == true && myTextBox2->CausesValidation == true )
      {
         button1->Text = "Disable Validation";
         myLabel->Text = "Validation Enabled";
         this->Focus();
      }
   }

   void myTextBox1_Validating( Object^ /*sender*/, System::ComponentModel::CancelEventArgs^ e )
   {
      if (  !CheckIfTextBoxNumeric( myTextBox1 ) )
      {
         myLabel->Text = "Has to be numeric";
         e->Cancel = true;
      }
   }

   void myTextBox1_Validated( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "Validated first control";
   }

   void myTextBox2_Validating( Object^ /*sender*/, System::ComponentModel::CancelEventArgs^ e )
   {
      if (  !CheckIfTextBoxNumeric( myTextBox2 ) )
      {
         myLabel->Text = "Has to be numeric";
         e->Cancel = true;
      }
   }

   void myTextBox2_Validated( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "Validated second control";
   }

   void myTextBox1_CausesValidationChanged( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "CausesValidation property was changed for First Textbox";
   }

   void myTextBox2_CausesValidationChanged( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      myLabel->Text = "CausesValidation property was changed for Second Textbox";
   }

   bool CheckIfTextBoxNumeric( TextBox^ myTextBox1 )
   {
      bool isValid = true;
      if ( myTextBox1->Text->Equals( "" ) )
      {
         isValid = false;
      }
      else
      {
         for ( int i = 0; i < myTextBox1->Text->Length; i++ )
         {
            if (  !(System::Char::IsNumber( myTextBox1->Text[ i ] )) )
            {
               myTextBox1->Text = "";
               isValid = false;
               break;
            }

         }
      }

      return isValid;
   }

   void myButtonAdd_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      try
      {
         int result = Convert::ToInt32( myTextBox1->Text ) + Convert::ToInt32( myTextBox2->Text );
         myLabel->Text = result.ToString();
      }
      catch ( Exception^ myException ) 
      {
         myLabel->Text = "Exception : ",myException->Message;
      }

   }

   void button1_Click( Object^ /*sender*/, System::EventArgs^ /*e*/ )
   {
      if ( myTextBox1->CausesValidation == false && myTextBox2->CausesValidation == false )
      {
         myTextBox1->CausesValidation = true;
         myTextBox2->CausesValidation = true;
         button1->Text = "Disable Validation";
         myLabel->Text = "Validation Enabled";
      }
      else
      if ( myTextBox1->CausesValidation == true && myTextBox2->CausesValidation == true )
      {
         myTextBox1->CausesValidation = false;
         myTextBox2->CausesValidation = false;
         button1->Text = "Enable Validation";
         myLabel->Text = "Validation Disabled";
      }
   }

private void AddHandlers()
{
    // Add the Validating and Validated handlers for textboxes.
    myTextBox1.add_Validating(new System.ComponentModel.
        CancelEventHandler(myTextBox1_Validating));
    myTextBox1.add_Validated(new System.EventHandler(myTextBox1_Validated));
    myTextBox2.add_Validating(new System.ComponentModel.
        CancelEventHandler(myTextBox2_Validating));
    myTextBox2.add_Validated(new System.EventHandler(myTextBox2_Validated));
    myTextBox1.add_CausesValidationChanged(new System.
        EventHandler(myTextBox1_CausesValidationChanged));
    myTextBox2.add_CausesValidationChanged(new System.
        EventHandler(myTextBox2_CausesValidationChanged));
    if (myTextBox1.get_CausesValidation() == true && myTextBox2.
        get_CausesValidation() == true) {
        button1.set_Text("Disable Validation");
        myLabel.set_Text("Validation Enabled");
        this.Focus();
    }
} //AddHandlers

private void myTextBox1_Validating(Object sender, 
    System.ComponentModel.CancelEventArgs e)
{
    if (!(CheckIfTextBoxNumeric(myTextBox1))) {
        myLabel.set_Text("Has to be numeric");
        e.set_Cancel(true);
    }
} //myTextBox1_Validating

private void myTextBox1_Validated(Object sender, 
    System.EventArgs e)
{
    myLabel.set_Text("Validated first control");
} //myTextBox1_Validated

private void myTextBox2_Validating(Object sender, 
    System.ComponentModel.CancelEventArgs e)
{
    if (!(CheckIfTextBoxNumeric(myTextBox2))) {
        myLabel.set_Text("Has to be numeric");
        e.set_Cancel(true);
    }
} //myTextBox2_Validating

private void myTextBox2_Validated(Object sender, System.EventArgs e)
{
    myLabel.set_Text("Validated second control");
} //myTextBox2_Validated

private void myTextBox1_CausesValidationChanged(Object sender, 
    System.EventArgs e)
{
    myLabel.set_Text("CausesValidation property was changed for "
        + "First Textbox");
} //myTextBox1_CausesValidationChanged

private void myTextBox2_CausesValidationChanged(Object sender, 
    System.EventArgs e)
{
    myLabel.set_Text("CausesValidation property was changed for "
        + "Second Textbox");
} //myTextBox2_CausesValidationChanged

private boolean CheckIfTextBoxNumeric(TextBox myTextBox1)
{
    boolean isValid = true;
    if (myTextBox1.get_Text().Equals("")) {
        isValid = false;
    }
    else {
        for (int i = 0; i < myTextBox1.get_Text().get_Length(); i++) {
            if (!(System.Char.IsNumber(myTextBox1.get_Text().
                get_Chars(i)))) {
                myTextBox1.set_Text("");
                isValid = false;
                break;
            }
        }
    }
    return isValid;
} //CheckIfTextBoxNumeric

private void myButtonAdd_Click(Object sender, System.EventArgs e)
{
    try {
        int result = Convert.ToInt32(myTextBox1.get_Text()) 
            + Convert.ToInt32(myTextBox2.get_Text());
        myLabel.set_Text(System.Convert.ToString(result));
    }
    catch (System.Exception myException) {
        myLabel.set_Text("Exception : " + myException.get_Message());
    }
} //myButtonAdd_Click

private void button1_Click(Object sender, System.EventArgs e)
{
    if (myTextBox1.get_CausesValidation() == false && myTextBox2.
        get_CausesValidation() == false) {
        myTextBox1.set_CausesValidation(true);
        myTextBox2.set_CausesValidation(true);
        button1.set_Text("Disable Validation");
        myLabel.set_Text("Validation Enabled");
    }
    else {
        if (myTextBox1.get_CausesValidation() == true && myTextBox2.
            get_CausesValidation() == true) {
            myTextBox1.set_CausesValidation(false);
            myTextBox2.set_CausesValidation(false);
            button1.set_Text("Enable Validation");
            myLabel.set_Text("Validation Disabled");
        }
    }
} //button1_Click

平台

Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。

版本信息

.NET Framework

受以下版本支持：2.0、1.1、1.0

请参见

参考

Control 类
Control 成员
System.Windows.Forms 命名空间
OnCausesValidationChanged
Control.CausesValidation 属性