When the checked state of a check box change, I would like to know what the new value is.
his is what I am doing:
Friend WithEvents clstTask As System.Windows.Forms.CheckedListBox
Private Sub clstTask_ItemCheck(ByVal sender As System.Object, ByVal e As System.Windows.Forms.ItemCheckEventArgs) Handles clstTask.ItemCheck
Dim SelectedCheckState As CheckState = clstTask.GetItemCheckState(clstTask.SelectedIndex)
End Sub
However, the value of the SelectedCheckState variable is not accuratley reflecting the new state. I think it is showing the current state before the click, as if this were a "Before_CheckChanged" event handler.
The Check box is a 3 state check box, (Checked, UnChecked, Undetermined). Do I have to write ugly code that assumes that if the CheckState returned is state "X" that the CURRENT state must be Y?
The ItemCheckEventArgs exposes properties CurrentValue and NewValue.
Check out ItemCheckEventArgs.NewValue and ItemCheckEventArgs.CurrentValue. This is why that parameter is there ;)
Related
I have a group box with multiple Checkboxes(food item) and each one has a corresponding NumericUpDown control(quantity). For context, it is for a project based on a restaurant menu. I want to hide a button called btnSave whenever either a checkbox is unchecked or the quantity (NumericUpDown) is changed. I currently have btnSave.Hide under the CheckBox1_CheckedChanged and NumericUpDown1_CheckedChanged SubProcedures but I want to know if there's a way to do this when anything within this group box is changed instead of putting the code under each SubProcedure. Thanks
I think you meant .ValueChanged for the NumericUpDown control. (There is no .CheckedChanged) Although this doesn't matter much in this case, this is a good pattern for future reference. Instead of calling an event call a Sub from your events.
When you have several controls responding to a single Event handler, you can find out which control triggered the event by checking the sender parameter. Since, as you can see, sender is an Object you will have to cast it to the appropriate type to get the properties of a CheckBox.
Private Sub HideSaveButton()
btnSave.Hide
End Sub
Private Sub CheckBoxInGroupBox_CheckedChanged(sender As Object, e As EventArgs) Handles CheckBox1.CheckedChanged, CheckBox2.CheckedChanged
HideSaveButton()
Dim WhichCheckBox As CheckBox = DirectCast(sender, CheckBox)
Select Case WhichCheckBox.Name
Case "CheckBox1"
MessageBox.Show("CheckBox1 has changed")
Case "CheckBox2"
MessageBox.Show("CheckBox2 has changed")
End Select
End Sub
Private Sub NumericUpDown1_ValueChanged(sender As Object, e As EventArgs) Handles NumericUpDown1.ValueChanged
HideSaveButton()
End Sub
I have a Datagridview in which a user will input data for shifts they have worked. I have a Checkbox to tick whether they require an on call payment for the shift. It's unchecked Value is "N" and when checked the value is "Y". This works well.
However when the user leaves the check box at it's default state from load, when i come to send it to the database i get an exception. How can I get the default value to always be "N" even if the user hasn't altered the box?
Error Message: Object Reference Not set to an instance of an object.
You need declare the checkbox in the datagrid item_databound
Private Sub dataGrid_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles dataGrid.ItemDataBound
If (e.Item.ItemType = ListItemType.Item) Or (e.Item.ItemType = ListItemType.AlternatingItem) Then
dim checkbox as checkbox = e.item.findControl("yourCheckboxID")
end if
end sub
i am making vb.net application in which there are 10 textbox in which i am changing background color when it got focus and lost focus. and adding validation number or character only. is there any way i can set or add custom code that every textbox added in form change color on got focus and lost focus and can assign textbox validation number only, alphanumeric. i don't want to add code on every event on keypress , gotfocus and lostfoucs. i just want to set it as default property of text box
here is my code
Private Sub txtProductDescc_GotFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtProductDescc.GotFocus
txtProductDescc.BackColor = interfaceDesign.gotFocusTxtColor
End Sub
Private Sub txtProductDescc_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtProductDescc.LostFocus
txtProductDescc.BackColor = interfaceDesign.lostFocusTxtColor
End Sub
One way, which I am using myself often, is to make an array of textboxes. This way they all share the same "code" for every event and you can select them by index if you need to address a specific item.
Updated
You can also capture key events on the main form:
C# capture main form keyboard events
How do I capture Keys.F1 regardless of the focused control on a form?
I have a spelling application that I am building in VB.Net, where I have a textbox receiving simple input (spelling words), and a label which will show the output. What I want to accomplish is when I enter something in the textbox, I can see it in my label - as I am typing into the textbox.
I will admit that I don't know what I'm doing, as I've never tried this before, so I don't know to begin in terms of setting up what I need to do. I know that I'll need some variable to hold my String input, and will probably need some type of loop, but beyond that, I am lost. The only other example is in C#, and doesn't help me any.
Can anyone give me a simple model to work off of, so I can put the approach into memory? For now, all I have is code stub from my TextChanged event handler:
Private Sub txtSpell_TextChanged(sender As Object, e As EventArgs) Handles txtSpell.TextChanged
'Set variables to hold values.
Dim someText As String
'Connect the label and textbox.
lblShowInput.Text = txtWordInput.Text
'Process loop to populate the label from textbox input.
for '(This is where I am lost on the approach)
End Sub
I know that I'll need some variable to hold my String input, and will
probably need some type of loop
I don't think you'll need a loop, or the variable to hold the value. You almost have it:
Private Sub txtSpell_TextChanged(sender As Object, e As EventArgs) Handles txtSpell.TextChanged
'Connect the label and textbox.
lblShowInput.Text = txtSpell.Text
End Sub
In the code you provided, you are referencing an object named txtWordInput inside your txtSpell text changed event handler. If you are entering the text in the txtWordInput input, you'll want to handle this in the txtWordInput textChanged event handler:
Private Sub txtWordInput_TextChanged(sender As Object, e As EventArgs) Handles txtWordInput.TextChanged
'Connect the label and textbox.
lblShowInput.Text = txtWordInput.Text
End Sub
Follow-up:
The TextChanged event is the correct event for this.
In your code, you are assigning lblShowInput.Text to txtWordInput.Text, but in the txtSpell TextChanged event handler.
You want to be in the TextChanged event handler for whatever TextBox you would like to use to update the label, as the text is changing.
To give a better example, I have created a simple Winforms VB application that has only a textbox named InputTextBox and a label named Output Label.
The Form:
The Code:
Public Class Form1
Private Sub InputTextBox_TextChanged(sender As System.Object, e As System.EventArgs) Handles InputTextBox.TextChanged
OutputLabel.Text = InputTextBox.Text
End Sub
End Class
Explanation:
InputTextBox_TextChanged is the method name generated by Visual Studio for our event handler
Handles InputTextBox.TextChanged ties the method to an actual event it is handling.
When the InputTextBox text property is changed (typically by user input), whatever we have in our InputTextBox_TextChanged Sub will execute. In this case, I am assigning the Text of OutputLabel to the Text of the InputTextBox
Output:
Resources:
I've uploaded this simple demo to GitHub if you'd like a closer look.
Take a look at the TextChanged documentation
I have a variable whose scope needs to be global, because it needs to be called in a function as well as in a button press. So I declared the variable in a Module so it would be global.
The problem is that the value of this variable needs to be equal to the value of the text property of a textbox in the form.
Here you can download the VB.net demonstration of my problem: http://db.tt/DDxQJDXl
Below is an explanation of what happens
You enter a string into the textbox, in this case I entered "Hello". Then you click the button and it displays what you wrote.
You click OK in that message box and change the value in the textbox. In this case I changed it to "Goodbye". Then I hit the button again, but the variable did not change values and the messagebox displays "Hello" again.
Here is the entire source code:
Module Module1
Public strDataValue = frmTest.txtDataValue.Text
End Module
Public Class frmTest
Private Sub btnTest_Click(sender As System.Object, e As System.EventArgs) Handles btnTest.Click
MsgBox(strDataValue)
End Sub
End Class
Note: This is just a demonstration of a problem I'm having in a much larger program so the variable does have to be global.
You need to set the value of the field to the new value in the TextBox:
Private Sub btnTest_Click(sender As System.Object, e As System.EventArgs) Handles btnTest.Click
strDataValue = txtDataValue.Text
MsgBox(strDataValue)
End Sub
The field will not change values by itself.
The value of strDataValue won't automatically change when txtDataValue.Text changes. You need to update strDataValue manually, either when the textbox loses focus, or when you click the Test button.
You could also have a public property, which automatically returns the actual value as long as the form is open.
Public ReadOnly Property DataValue() As String
Get
Return frmTest.txtDataValue.Text
End Get
End Property
You need to assign value of txtDataValue.Text to your variable strDataValue in better performance
Using of Timer object or TextChenged event not recommended
Any change of txtDataValue.Text can assign after end of editing action
for me best solution: Leave or LostFocus events
Private Sub txtDataValue_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtDataValue.Leave
strDataValue = txtDataValue.Text
End Sub