Friends,
Right now, when you select any of the namesin combobox (ComboBox_Names), the sametext appears on thelabel.
I just wish that this sameeffect of a label,appearedin FORM2.
How do I? What is thecode?
My greetings.
Option Strict On
Option Explicit On
Public Class Form1
Private namesList As New List(Of String)
Private namesFileLocation As String = Application.StartupPath & "\Names.txt"
'
'
'
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles MyBase.Load
Button_AddNewName.Enabled = False
ComboBox2.DropDownStyle = ComboBoxStyle.DropDownList
ComboBox_Names.DropDownStyle = ComboBoxStyle.DropDownList
' Check to see if the stored text file exists:
If My.Computer.FileSystem.FileExists(namesFileLocation) Then
' Now read each line in:
Using rdr As New System.IO.StreamReader(namesFileLocation)
Do While rdr.Peek() >= 0
Dim itm As String = rdr.ReadLine
itm = itm.Trim
If itm <> "" Then
' Add it to the list of names:
namesList.Add(itm)
End If
Loop
End Using
End If
' Test to see if the names list has items in it
' and if so, put them into the items of the names
' combobox:
For Each personName As String In namesList
' Note there's no "testing" needed; if the
' list is empty, it never gets this far.
ComboBox_Names.Items.Add(personName)
ComboBox2.Items.Add(personName)
Next
' Now check whether or not there's anything
' to show and, if so, enable the appropriate
' controls:
CheckOkToEnableButtons()
End Sub
'
'
'
Private Sub Form1_FormClosing(ByVal sender As Object, _
ByVal e As System.Windows.Forms.FormClosingEventArgs) _
Handles Me.FormClosing
' This event is triggered as Form1 is closing. Let's
' save the list to the text file. Since it very well
' may be a large list and the text file may or may
' not yet exist, let's use a stringbuilder, build
' the entire text to write, then create the text
' file (if it does not exist) or overwrite the text
' file (if it does exist). First let's make sure
' that the form is closing because the user has
' closed it, then if that's the case, we'll do the
' rest of it:
If e.CloseReason = CloseReason.UserClosing Then
Dim sb As New System.Text.StringBuilder
For Each personName As String In namesList
sb.AppendLine(personName)
Next
' Now write the contents of the stringbuilder
' IF the stringbuilder actually has something
' in it:
If sb.ToString.Length > 0 Then
My.Computer.FileSystem.WriteAllText(namesFileLocation, _
sb.ToString, False)
End If
End If
End Sub
'
'
'
Private Sub TextBox_NewName_TextChanged(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles TextBox_NewName.TextChanged
' This event is fired anytime that the text in the textbox
' (TextBox_NewName) has changed. We'll test to see if the
' text "trimmed" is blank. If it's not, then we'll enable
' the button to allow them to add it:
If TextBox_NewName.Text.Trim <> "" Then
Button_AddNewName.Enabled = True
Else
Button_AddNewName.Enabled = False
End If
End Sub
'
'
'
'
'
'
Private Sub Button_AddNewName_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button_AddNewName.Click
' Test that the name isn't already in the list and, if not,
' then add the new name:
If Not namesList.Contains(TextBox_NewName.Text.Trim) Then
' Add it both to the main list and to the combobox's items
namesList.Add(TextBox_NewName.Text.Trim)
ComboBox_Names.Items.Add(TextBox_NewName.Text.Trim)
ComboBox2.Items.Add(TextBox_NewName.Text.Trim)
CheckOkToEnableButtons()
Else
' Show a message indicating that the name entered
' is already in the combobox's items:
MessageBox.Show("The name that you've entered is already" & vbCrLf & _"in the names combobox.", "Cannot Add This Name", _
MessageBoxButtons.OK, MessageBoxIcon.Warning)
End If
' There's a basic fallacy that using the .Contains method won't
' detect. For instance, what if they typed in the following:
'
' Frank Smith
'
' Then later typed in this:
'
' frank smith
'
' See the problem? To the program, they're not the same so
' it will allow it. Another example is this:
'
' Frank Smith
'
' Frank Smith
'
' Again, to the computer they aren't the same. Is there a way
' that we can make the program work so that it will not allow
' these types of dupicates? Yes. LINQ would be a good tool to
' use but if you're not familiar with it, then it will appear
' to have a very odd syntax and it's bound to be more confusing
' than helpful, so instead I'll just iterate through the list
' and test it. The following is commented out so it doesn't
' actually work but if you want to try it, then comment out
' the code above, and uncomment out what follows:
'
'
'If CheckForDuplicates(TextBox_NewName.Text.Trim) Then
' MessageBox.Show("The name that you've entered is already" & vbCrLf & _
' "in the names combobox.", "Cannot Add This Name", _
' MessageBoxButtons.OK, MessageBoxIcon.Warning)
'Else
' namesList.Add(TextBox_NewName.Text.Trim)
' ComboBox_Names.Items.Add(TextBox_NewName.Text.Trim)
' CheckOkToEnableButtons()
'End If
With TextBox_NewName
.Clear()
.Focus()
End With
End Sub
'
'
'
Private Sub Button_ShowForm2_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button_ShowForm2.Click
' We'll pass the list of names to Form2 after we first
' create a new instance of Form2:
Using f2 As New Form2
f2.listOfNames = namesList
' Now show it modally:
f2.ShowDialog()
End Using
End Sub
'
'
'
Private Sub Button_ShowForm3_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button_ShowForm3.Click
' We'll pass the list of names to Form3 after we first
' create a new instance of Form3:
Using f3 As New Form3
f3.listOfNames = namesList
' Now show it modally:
f3.ShowDialog()
End Using
End Sub
'
'
'
Private Sub Button_ShowForm4_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button_ShowForm4.Click
' We'll pass the list of names to Form4 after we first
' create a new instance of Form4:
Using f4 As New Form4
f4.listOfNames = namesList
' Now show it modally:
f4.ShowDialog()
End Using
End Sub
'
'
'
Private Sub CheckOkToEnableButtons()
' This sub just checks to see if there's anything
' in the namesList (and subsequently in the
' combobox) and if so, it enables the appropriate
' controls but if not, it disables them:
If namesList.Count > 0 Then
Button_ShowForm2.Enabled = True
Button_ShowForm3.Enabled = True
Button_ShowForm4.Enabled = True
ComboBox_Names.Enabled = True
Else
Button_ShowForm2.Enabled = False
Button_ShowForm3.Enabled = False
Button_ShowForm4.Enabled = False
ComboBox_Names.Enabled = False
End If
End Sub
Private Function CheckForDuplicates(ByVal name As String) As Boolean
Dim retVal As Boolean = False
For i As Integer = 0 To namesList.Count - 1
' Let's change the value that we actually test
' (both in the parameter passed in and in the
' list of names) to lower case and, if either
' contains a space character, we'll take those
' out also:
Dim nameToTest As String = name.ToLower
If nameToTest.Contains(" "c) Then
nameToTest = nameToTest.Replace(" "c, "")
End If
' Now we'll do the same with the name in
' the list that the counter is presently
' referring to:
Dim nameInTheList As String = namesList(i).ToLower
If nameInTheList.Contains(" "c) Then
nameInTheList = nameInTheList.Replace(" "c, "")
End If
' Now we can test it:
If nameInTheList = nameToTest Then
' Yep! It's a match!
retVal = True
Exit For
End If
Next
Return retVal
End Function
Private Sub ListView1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
' Let's create a new list, this time the list will hold
' integers:
Dim numbersList As New List(Of Integer)
' I'll populate the list just by going through a small
' loop:
For i As Integer = 1 To 10
numbersList.Add(i)
Next
' Now the list has a count of 10. Let's remove the one
' that has the number 7 in it.
For i As Integer = 0 To numbersList.Count - 1
' First, note that I start at 0 and go through
' the list's quantity (count) minus one. That's
' because it's a zero-based list as are most
' things in .NET so the first item has an
' index of 0, the second has an index of 1, and
' so on.
'
' Let's find the one with 7:
If numbersList(i) = 7 Then
' Ah, found it!
'
' Now how do I eliminate it without getting an
' exception? Let's try it and see:
numbersList.RemoveAt(i)
' Run into a problem? ;-) Yes ... it just threw
' an "index out of range" exception. So how to
' do it then? Try this now:
Exit For
' To make my example work you'll need to comment
' out the "Exit For" above. If you do then you'll
' get the exception, but let me explain why that
' worked:
'
' The only time that it actually throws an exception
' isn't when you remove it; it's when it does that
' then tries to continue on in the loop, so as soon
' as it gets to "Next", jumps back to the top (the
' "For"), bang - exception. Why? Because you just
' changed the count when you removed it, so the way
' to do it is to find it like I showed above, remove
' it, then jump OUT of the loop.
'
' If you have more than one to do then the entire
' thing will have to be inside a do loop or some other
' type loop but this example is a simple one with just
' one being removed at a time.
End If
Next
End Sub
Private Sub ComboBox_Names_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles ComboBox_Names.SelectedIndexChanged
' The selected index has changed. Now verify that it's
' not at index -1 (which is "nothing selected") and if
' so, enable the button to remove the name.
If ComboBox_Names.SelectedIndex > -1 Then
Button_RemoveSelectedName.Enabled = True
Else
Button_RemoveSelectedName.Enabled = False
End If
End Sub
Private Sub ComboBox2_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles ComboBox2.SelectedIndexChanged
' The selected index has changed. Now verify that it's
' not at index -1 (which is "nothing selected") and if
' so, enable the button to remove the name.
If ComboBox2.Text = String.Empty Then
ComboBox2.SelectedIndex = -1
ComboBox2.Select()
End If
If ComboBox2.Text = ComboBox_Names.Text Then
MessageBox.Show("Por favor escolha outro nome", "Designar irmão", MessageBoxButtons.OK)
ComboBox2.SelectedIndex = -1
ComboBox2.Select()
End If
End Sub
'
'
'
Private Sub Button_RemoveSelectedName_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
Handles Button_RemoveSelectedName.Click
' The button to remove the selected name from
' the list of names.
With Button_RemoveSelectedName
.Enabled = False
.Refresh()
End With
' Find the name in the list of names:
Dim selectedName As String = ComboBox_Names.Items(ComboBox_Names.SelectedIndex).ToString
For i As Integer = 0 To namesList.Count - 1
If namesList(i) = selectedName Then
' Found the name, so remove it and and jump out
' of the loop by using the "Exit For":
namesList.RemoveAt(i)
Exit For
End If
Next
' Now clear the control's list:
ComboBox_Names.Items.Clear()
ComboBox2.Items.Clear()
' And lastly, refill the control's
' items:
For Each personName As String In namesList
ComboBox_Names.Items.Add(personName)
ComboBox2.Items.Add(personName)
Next
End Sub
Private Sub Label3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label3.Click
End Sub
Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox_Names.SelectedIndexChanged
Label3.Text = ComboBox_Names.SelectedItem.ToString
End Sub
End Class