I'm make new vb.net application that open many "form2" form "form1" with button
my code :
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
For i As Integer = 1 To 5
Form2.Show()
Next
End Sub
but this code show only 1 "form2", how can i Fix it ?
By using the class name you are referring to the default instance and there is only ever one default instance at a time. If you want multiple instances simultaneously then you need to create them yourself.
For i As Integer = 1 To 5
Dim f2 As New Form2
f2.Show()
Next
You might like to check out my blog post on the subject of default instances to learn more.
By the way, you can also combine the two lines within that loop into one, but note that you cannot start a line with the New keyword, so this is one of the few times that the Call keyword is useful.
For i As Integer = 1 To 5
Call New Form2().Show()
Next
You need to create new instances.For example:
For i As Integer = 1 To 5
Dim frm As New Form2
frm.Show()
Next
In case you need to access those instances you can keep them in a List
Dim forms As New List(Of Form)(5)
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
For i As Integer = 1 To forms.Capacity
Dim frm As New frmBaleRevision
forms.Add(frm)
frm.Show()
Next
End Sub
You can do with this code and change the properties of each form (in this example it gonna be the text of the form):
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
For i As Integer = 1 To 5
Dim x As New Form2
x.Text = "New Form " & i
x.Show()
Next
End Sub
Related
This is my first time working with VB.Net It's a college assignment and is already due for submission.I want to create a simple program that determines if a user has Ebola or not. So, there is a list of checkbox containing the core symptoms of Ebola. If the user selects 4 or more there should be a prompt message saying the user most likely has Ebola otherwise user does not have Ebola.
I have created the form and it works but don't know how to implement the checkbox into numbers that will be summed up.
Here is the code for the form
Public Class Checkbxvb
Private Sub Checkbxvb_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Label1.Text = "Click to select the symptoms you are having"
CheckBox1.Text = "Fever"
CheckBox2.Text = "Loss of appetite"
CheckBox3.Text = "sore throat"
CheckBox4.Text = "Gastrointestinal Symptoms"
CheckBox5.Text = "Unexplained bleeding or bruising"
CheckBox6.Text = "Loss of weight"
Button1.Text = "Submit"
Button2.Text = "Close"
End Sub
I want to create a button that will collect the user input like I said earlier on. Thanks
If you are using a CheckListBox you can used its CheckedItems collection Count property to get what you need.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If CheckedListBox1.CheckedItems.Count > 3 Then
MessageBox.Show("You may have Ebola.")
Else
MessageBox.Show("You probably don't have Ebola.")
End If
End Sub
If you are using CheckBox controls add them to a List(Of T). The T stands for Type. Create a variable for the list at Form level so it can be seen from the Form.Load and the button click. Then you can loop through your collection and increment a counter when the Checked property is True.
Private CkBxList As New List(Of CheckBox)
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
CkBxList.AddRange({CheckBox1, CheckBox2, CheckBox3, CheckBox4})
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim counter As Integer
For Each cb In CkBxList
If cb.Checked Then
counter += 1
End If
Next
If counter > 3 Then
MessageBox.Show("You may have Ebola.")
Else
MessageBox.Show("You probably don't have Ebola.")
End If
End Sub
As you can see the code is much simpler with a CheckedListBox. Try to use the control that best suits your purpose.
I did some activity but I cant figure out how to retrieve data from listbox1 to textbox1. Example in the listbox1 there are 4 names: John, Jorge, Joe. Then I want to transfer Joe from listbox1 to textbox1. I did an arraylist where I adding those 3 names in the listbox1 but I didn't know how to retrieve the name "Jorge" from listbox1 to textbox1. Send help.
Here's the code where I try to retrieve one of the name from listbox1 to textbox1
Private Sub Retrievebtn_Click(sender As Object, e As EventArgs) Handles Retrievebtn.Click
If textbox1.Text = ListBox1.Items.Count Then
textbox1.Text = ArrayofNames(x)
End If
End Sub
Here's the whole code
Public Class Form1
Dim ArrayofNames() As String
Dim x As Integer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Private Sub Retrievebtn_Click(sender As Object, e As EventArgs) Handles Retrievebtn.Click
If textbox1.Text = ListBox1.Items.Count Then
textbox1.Text = ArrayofNames(x)
End If
End Sub
Private Sub Addbtn_Click(sender As Object, e As EventArgs) Handles Addbtn.Click
Dim x As Integer = 0
ReDim ArrayofNames(x)
For x = 0 To ArrayofNames.Length - 1
ArrayofNames(x) = Addtextbox.Text
ListBox1.Items.Add(ArrayofNames(x))
Next
End Sub
Private Sub removeBtn_Click(sender As Object, e As EventArgs) Handles removeBtn.Click
ListBox1.Items.Remove(ListBox1.SelectedItem)
End Sub
End Class
Here's the Image of the interface i try to retrieve the name Joe but it wasn'tshowing
Let's go over the code you posted.
In the retrieve button click event you are comparing and Integer to a String with textbox1.Text = ListBox1.Items.Count This won't compile with Option Strict On. You do have Option Strict On, don't you? You should always have this on.
On the next line, you assign the value of ArrayofNames(x), where x refers to your form level variable, to a text box's Text property. Since the value of x is never changed anywhere in the code this will always return the 0 index in the array. (The first element) I can't imagine why it should matter that the Textbox.Text should equal the count of the ListBox items.
In the add button click event you first declare a local variable x. Any code in the method will use this x, not the form level x. You ReDim (without the Preserve keyword) the array to an array with a single element. Your For loop is silly because the length of ArrayofNames is 1, so it is 0 To 0.
The ArrayofNames will never have more than a single element and it will be overwritten each time the add button is clicked.
Fortunately the Listbox maintains its own collection of items.
We can use this collection to simplify your code. Just add the contents of the text box to the the list items.
To retrieve a value from the list box you must first determine if the user has entered a valid index. First, is the entry a valid Integer and is it an index present in the list box.
Remember that .net collections start at index 0.
I use default names in my test program but you should continue to use meaningful names for your controls.
'Your add button
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim index As Integer
If Integer.TryParse(TextBox1.Text, index) AndAlso index >= 0 AndAlso ListBox1.Items.Count - 1 >= index Then
TextBox2.Text = ListBox1.Items(index).ToString
End If
End Sub
'Your add button
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
ListBox1.Items.Add(TextBox3.Text)
End Sub
sorry to come in here like this looking for answers, but im actually really stumped. Im supposed to make an application using 2 forms, one to generate its own array and store user entered numbers into another array, and then display them on the second form and tell you how many of the numbers are in common
I cant get the numbers to show up on the second form at all, and I also cant really understand how to get how many numbers are matching, but I will when I can reference them properly in form 2. I got the arrays set up perfectly, but I cant even call the numbers from them to form 2. I need help calling the arrays from the first form to display on the next
Form 1 code
Public Class Form1
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnExit.Click
Me.Close()
End Sub
Shared random As New Random()
Dim UserArray(4) As String
Dim LotteryArray(4) As String
Public Sub btnCheck_Click(sender As Object, e As EventArgs) Handles btnCheck.Click
If txtNumbers.Text <> "" Then
For i As Integer = 0 To 4
If UserArray(i) = "" Then
UserArray(i) = txtNumbers.Text
End If
Next
End If
For n As Integer = 0 To 9
Dim RandomNumber As Integer = CInt(Int(Rnd() * 5) + 1)
LotteryArray(4) = CStr(RandomNumber)
Next
End Sub
End Class
Form 2 Code
Public Class Form2
Public Sub btnOk_Click(sender As Object, e As EventArgs) Handles btnOk.Click
lblUser1.Text = Form1.UserArray(0)
lblUser2.Text = Form1.UserArray(1)
lblUser3.Text = Form1.UserArray(2)
lblUser4.Text = Form1.UserArray(3)
lblUser5.Text = Form1.UserArray(4)
lblRand1.Text = Form1.LotteryArray(0)
lblRand2.Text = Form1.LotteryArray(1)
lblRand3.Text = Form1.LotteryArray(2)
lblRand4.Text = Form1.LotteryArray(3)
lblRand5.Text = Form1.LotteryArray(4)
If Form1.LotteryArray(4) = Form1.UserArray(4) Then
MessageBox("CONGRATULATIONS!", "You Are The GRAND PRIZE WINNER!")
End If
Me.Close()
End Sub
End Class
I will address your first question. How to get your numbers into your second form.
You main problem is the Access modifier you used for your arrays. Dim is the equivalent of Private which means that the variable is only visible within the class. Friend is visible anywhere in the assembly. See https://learn.microsoft.com/en-us/dotnet/visual-basic/programming-guide/language-features/declared-elements/access-levels for more information. Don't change your event procedure Access to Public.
You have to let the user fill in another guess. The first loop in the Check button will only enter the same input 5 times. You need one entry on every click but you need to keep track of where you are in the array. Private NumberOfGuesses As Integer Note that this variable is Private. It doesn't need to be seen outside of the Form1 class.
We don't need to refill the LotteryArray on every click so I did it once in the Form.Load You were trying to use the Random class the way you use the old vb6 Random. The .net class is much easier.
To display the arrays on Form2, I used list boxes and loops. Saved a bit of typing.
If you still have a question about part 2 of your problem post another question. Show what you have tried.
Public Class Form1
Private random As New Random()
Friend UserArray(4) As Integer
Friend LotteryArray(9) As Integer
Private NumberOfGuesses As Integer
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
For n As Integer = 0 To 9
Dim RandomNumber As Integer = random.Next(0, 10)
LotteryArray(n) = RandomNumber
Next
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
If NumberOfGuesses > 4 Then
MessageBox.Show("You have used up your guesses")
Form2.Show()
Me.Close()
End If
If TextBox1.Text <> "" Then
UserArray(NumberOfGuesses) = CInt(TextBox1.Text)
NumberOfGuesses += 1
TextBox1.Clear()
TextBox1.Focus()
End If
End Sub
End Class
Public Class Form2
Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load
For Each number In Form1.UserArray
ListBox1.Items.Add(number)
Next
For Each number In Form1.LotteryArray
ListBox2.Items.Add(number)
Next
End Sub
End Class
I'm trying to understand more about VB.NET and Multiple forms so I can make my code better.
I have a SQL database table that holds the live data for all 14 processes, the monitor program updates a form showing the progress of all the processes. Years ago in MS Access I would have simply used a rolling subform to show the contents of the table.
However, my first attempt in VB.NET is to have "many" textboxes, basically 14 lines of textboxes and my code has 14 very similar parts updating all the textboxes. There has to be a better way :(
For Example:
txtProcessID1.Text TxtStatus1.Text ProgressBar1 ......
txtProcessID2.Text TxtStatus2.Text ProgressBar2 ......
txtProcessID3.Text TxtStatus3.Text ProgressBar3 ......
So, I'm trying to come up with a code where I create a SubForm that looks like one controller line, then create 14 instances of this subform on my mainform.
My test code seems to work but the textboxes on the subforms are not updating the contents on screen!! Even though when I call back the contents of .text it is what I expect.
Why does this example code not work, and is my solution the best way to complete this?
Public Class MainForm
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
SubForm.SetText = Me.TextBox1.Text ' Try to change contents of a TextBox on the SubForm
Me.TextBox2.Text = SubForm.SetText ' Data comes back as expected, but the subform textbox remains unchanged.
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
Dim objSubForm As New SubForm()
objSubForm.TopLevel = False
Me.Panel1.Controls.Add(objSubForm)
objSubForm.Show()
End Sub
End Class
Public Class SubForm
Public Property SetText() As String
Get
SetText = TextBox1.Text
End Get
Set(ByVal Value As String)
Me.TextBox1.Text = Value ' Control is not updated of the SubForm.
Debug.Print("Value = " & Value) ' The Value is Passed Correctly.
Debug.Print("Text = " & TextBox1.Text) ' And the property of the control has been updated.
End Set
End Property
End Class
Many Thanks
Kev
In your button click you are referencing the class name SubForm, this in VB.NET is called as the default automatic instance of a form, but this is not the same instance that you display in your Form_Load. Here you create a different instance called objSubForm and this is the instance that you display.
To fix you need to keep the objSubForm as a global instance and refer to this global when you click
Public Class MainForm
Dim objSubForm As SubForm
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
objSubForm.SetText = Me.TextBox1.Text ' Try to change contents of a TextBox on the SubForm
Me.TextBox2.Text = objSubForm.SetText ' Data comes back as expected, but the subform textbox remains unchanged.
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
objSubForm = New SubForm()
objSubForm.TopLevel = False
Me.Panel1.Controls.Add(objSubForm)
objSubForm.Show()
End Sub
End Class
Keep in mind that after this change you are responsible to effectively close and dispose the global instance.
Private Sub Form1_FormClosed(sender as Object, e as FormClosedEventArgs) _
Handles Form1.FormClosed
if objSubForm IsNot Nothing
objSubForm.Close
End If
objSubForm = Nothing
End Sub
Thanks Steve, I applied the new code in just half an hour based on your fix.
Here's a basic example of my code that gives me 14 subforms I can update.
I've moved away from creating a property in the subform in favour of directly updating the TextBox control.
The solution has given me "MUCH" less code and now I can add another detail to the one subform and show that for all processes.
Thanks Again!
Kev
Public Class MainForm
Dim objSubForm(14) As SubForm
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
'Update the 14 forms
For n = 0 To 13
objSubForm(n).TextBox1.Text = Me.TextBox1.Text & " " & n
Next
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
' create 14 subforms
For n = 0 To 13
objSubForm(n) = New SubForm()
objSubForm(n).TopLevel = False
Me.Panel1.Controls.Add(objSubForm(n))
objSubForm(n).Location = New Point(0, 20 * n)
objSubForm(n).Show()
Next
End Sub
Private Sub MainForm_FormClosed(sender As Object, e As FormClosedEventArgs) Handles MyBase.FormClosed
' CLear up
If objSubForm IsNot Nothing Then
For n = 0 To 13
objSubForm(n).Close()
Next
End If
For n = 0 To 13
objSubForm(n) = Nothing
Next
End Sub
End Class
So basically you have a main form that shows only a label (lblTotalPrice) and a button that when you click it, it opens a second form that contains a listbox with different prices packages (lstPackages). How do do you select an item from lstPackages that is on the second form and return it to lblTotalPrice, which is located on the main form?
I attempted this code using a function (thought it would be useful for calculations), but it seems like it didn't work:
On my second form, I populated the lstPackages with it's name using parallel arrays:
Dim strPackages As String = {"Package 1", "Package 2", "Package 3", "Package 4", "Package 5"}
Dim decPrice As String = {100D, 200D, 300D, 400D, 500D}
Private Sub SecondForm_Activated(sender As Object, e As EventArgs) Handles MyBase.Activate
Dim frmMain as New
Dim i As Integer
For i = 0 To strPackages.Length - 1
lstPackages.Items.Add(strPackages(i))
Next
End Sub
After I tried to select a value on lstPackages, but I just was not too sure if I was using the right code to select the item and return it to the main form:
Function CalcPackage()
Dim decPackages As Decimal = 0D
If lstPackages.SelectedIndex = -1 Then
MessageBox.Show("Select a package")
Else
For i = 0 To lstPackages.SelectedItem - 1
decPackages = lstPackages.SelectedItem(i)
Next i
End If
Return decPackages
End Function
When I have selected the item in the lstPackages, I tried to send the selected item back to the main form, but ran into a problem here:
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnClose.Click
Dim frmMainForm As New MainForm
Dim decTotal As Decimal
decTotal = CalcPackage()
'I was stuck in this part and wasn't sure how to return it to lblTotalPrice (and also close the second form too)
frmMainForm.lblTotalPrice.Text = decTotal.ToString("c")
frmMainForm.Show()
Me.Close()
End Sub
So yea sorry if my code is weird, but I'm hoping to get help on how to return the value of the item to lblTotalPrice on the main form, thanks guys
Part of your problem is that you are newing up an instance of the main form in the button exit click event handler of the second form, as shown in this code posted:
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnClose.Click
Dim frmMainForm As New MainForm
Dim decTotal As Decimal
decTotal = CalcPackage()
'I was stuck in this part and wasn't sure how to return it to lblTotalPrice (and also close the second form too)
frmMainForm.lblTotalPrice.Text = decTotal.ToString("c")
frmMainForm.Show()
Me.Close()
End Sub
Instead pass an instance of the main form to the second form via its constructor, like this:
Public Class SecondForm Inherits Form
Dim theMainForm As MainForm
Public Sub New(mainForm As MainForm)
theMainForm = mainForm
End Sub
End Class
Now you can reference the lblTotalPrice in the MainForm class via the theMainForm variable, like this:
theMainForm.lblTotalPrice.Text = lstPackages.SelectedItem
The theMainForm.lblTotalPrice.Text should only be updated in response to an item being selected from lstPackages not when the second form is closed; so handle the updating of the main form's label in the SelectedIndexChanged event of lstPackages, like this:
Protected Sub lstPackages_IndexChanged(sender As Object, e As EventArgs)
Dim decTotal As Decimal
decTotal = CalcPackage()
theMainForm.lblTotalPrice.Text = decTotal.ToString("c")
End Sub
All the exit button click event handler should do is to show the main form and close the second form, like this:
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnClose.Click
theMainForm.Show()
Me.Close()
End Sub
Just display SecondForm with ShowDialog(), then retrieve the value with the reference to it that you already have:
Public Class MainForm
Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
Dim sf As New SecondForm
If sf.ShowDialog = Windows.Forms.DialogResult.OK Then
lblTotalPrice.Text = sf.TotalPrice
End If
End Sub
End Class
Over in SecondForm:
Public Class SecondForm
Private _TotalPrice As Decimal
Public ReadOnly Property TotalPrice As Decimal
Get
Return _TotalPrice
End Get
End Property
Private Sub btnExit_Click(sender As Object, e As EventArgs) Handles btnClose.Click
If lstPackages.SelectedIndex = -1 Then
MessageBox.Show("Select a package")
Else
_TotalPrice = lstPackages.SelectedItem(0)
Me.DialogResult = Windows.Forms.DialogResult.OK
End If
End Sub
End Class