VB.NET-避免在单击“重置”按钮时执行MsgBox

Question

I just started coding in my college using Visual Basic, and I am still learning how to code.

My question is: When the Click event is handled for a reset button in my Form, all the TextBox es which say MsgBox("Please insert a value.") is executed. Is there any other way to use these functions without executing those MsgBox ? I want to not raise the MsgBox es when the reset button is clicked.

Here is my code:

Public Class MainWindowApp
    '--------------------------------------------------------------------------------------------------------------------------------
    'Program Info
    '--------------------------------------------------------------------------------------------------------------------------------
    'Program:   Calculate the Average - Windows Forms
    'Date:      10/10/2018
    'Author:    Edino de Souza
    'Operation: Create a VB Form application that will prompt the user for 3 different numbers. 
    '           It should Then calculate the average of those 3 numbers And display the Average To the user On the Console. 
    '           The output message should read As follows
    '           The Average Of Number 1 And Number 2 And Number 3 Is Answer.
    '           Ex. The Average of 90 And 80 And 70 Is 80
    '           2) Using if statements, prevent user input errors from occurring when clicking the Calculate button.
    '           The following should be checked:
    '               a) That a Value was provided for each edit box.
    '               b) That the value input is a number (Note the isNumeric function can be used for this).
    '               c) That the value entered in to the number boxes are not Less than 0 and not greater than 100.
    '           If the value falls under one of the conditions above, use the messagebox function to display a relevant message
    '           to the user (Note, if you want to place the cursor in the textbox being checked automatically, you can call the
    '           focus function of the textbox you are checking)
    '           3) If you are not using a label control to report the result of the calculation, add one to your form. Once the
    '           average has been calculated, set the text of your label control to the average. Using if statements, based on 
    '           the resulting grade, change the text as follows:
    '           60% and above, change the text to green
    '           Below 60%, set the color to red
    '           The forecolor property of the label can be used to change the color.
    '
    '--------------------------------------------------------------------------------------------------------------------------------
    'Change Log
    '--------------------------------------------------------------------------------------------------------------------------------
    'Date               Programmer          Change
    '--------------------------------------------------------------------------------------------------------------------------------
    '10/10/2018         Edino de Souza      Initial/Final Version
    '10/15/2018         Edino de Souza      Adjusted reset button to reset variables too.
    '10/17/2018         Edino de Souza      First part of the addition of the IF statements
    '10/17/2018         Edino de Souza      Adjusted the code to perform what is required.
    '--------------------------------------------------------------------------------------------------------------------------------


    'Begin of Variables Session

    Public num1 As Decimal
    Public num2 As Decimal
    Public num3 As Decimal
    Public CalcAverage As Decimal

    'End of Variables Session


    'Begin of Input Session 1

    Private Sub text_num1_TextChanged(sender As Object, e As EventArgs) Handles text_num1.TextChanged

        'TextBox and Clear button controlling.

        text_num1.Enabled = True    'Enable textbox 1
        Bt_Clear1.Enabled = True    'Enable clear button 1

        text_num2.Enabled = False   'Disable textbox 2
        Bt_Clear2.Enabled = False   'Enable clear button 2

        text_num3.Enabled = False   'Disable textbox 3
        Bt_Clear3.Enabled = False   'Disable button 3

        LabelCalcAverage.Enabled = False    'Disable the calculator button
        Tx_Average.Enabled = False      'Disable the average textbox

        'End - TextBox and Clear button controlling.


        'Section to verify if all the conditions were satisfied.

        If text_num1.Text = Nothing Then
            MsgBox("Please insert a value.")
            text_num2.Enabled = False

        ElseIf IsNumeric(text_num1.Text) = False Then
            MsgBox("Please insert a number")
            text_num2.Enabled = False

        ElseIf (text_num1.Text) < 0 Then
            MsgBox("Please insert a number greater than zero")
            text_num2.Enabled = False

        ElseIf (text_num1.Text) > 100 Then

            MsgBox("Please insert a number less than one hundred")
            text_num2.Enabled = False

        Else

            Decimal.TryParse(text_num1.Text, num1)

            text_num2.Enabled = True    'Enable textbox 2 after all validations
            Bt_Clear2.Enabled = True    'Enable textbox 2 clear button after all validations

        End If

        'End - Section to verify if all the conditions were satisfied.


    End Sub

    'End of Input Session 1

    'Begin of Input Session 2

    Private Sub text_num2_TextChanged(sender As Object, e As EventArgs) Handles text_num2.TextChanged

        If text_num2.Text = Nothing Then
            MsgBox("Please insert a value.")
            text_num3.Enabled = False

        ElseIf IsNumeric(text_num2.Text) = False Then
            MsgBox("Please insert a number")
            text_num3.Enabled = False

        ElseIf (text_num2.Text) < 0 Then
            MsgBox("Please insert a number greater than zero")
            text_num3.Enabled = False

        ElseIf (text_num2.Text) > 100 Then

            MsgBox("Please insert a number less than one hundred")
            text_num3.Enabled = False

        Else

            Decimal.TryParse(text_num2.Text, num2)

            text_num3.Enabled = True    'Enable textbox 3 after all validations
            Bt_Clear3.Enabled = True    'Enable textbox 3 clear button after all validations

        End If


    End Sub


    'End of Input Session 2


    'Begin of Input Session 3

    Private Sub text_num3_TextChanged(sender As Object, e As EventArgs) Handles text_num3.TextChanged

        If text_num3.Text = Nothing Then
            MsgBox("Please insert a value.")

        ElseIf IsNumeric(text_num3.Text) = False Then
            MsgBox("Please insert a number")

        ElseIf (text_num3.Text) < 0 Then
            MsgBox("Please insert a number greater than zero")

        ElseIf (text_num3.Text) > 100 Then

            MsgBox("Please insert a number less than one hundred")

        Else

            Decimal.TryParse(text_num3.Text, num3)
            LabelCalcAverage.Enabled = True     'Enable the calculator button only after all fields were filled

        End If


    End Sub


    'End of Input Session 3


    'Caculation session
    Private Sub LabelCalcAverage_Click(sender As Object, e As EventArgs) Handles LabelCalcAverage.Click

        CalcAverage = (num1 + num2 + num3) / 3

        Tx_Average.Enabled = True


        'Function to show different colors on TextBox and Label

        If CalcAverage < 60 Then
            Tx_Average.ForeColor = Color.Yellow

            Tx_Average.BackColor = Color.Red

            Label_Average.BackColor = Color.Red

            Tx_Average.Text = CalcAverage.ToString("###.##")

        ElseIf CalcAverage >= 60 Then
            Tx_Average.ForeColor = Color.Yellow

            Tx_Average.BackColor = Color.Green

            Label_Average.BackColor = Color.Green

            Tx_Average.Text = CalcAverage.ToString("###.##")

        End If

        'End of function to show different colors on TextBox and Label


        'Disable all textbox and clear buttons after Calculate button was pressed

        text_num1.Enabled = False
        Bt_Clear1.Enabled = False

        text_num2.Enabled = False
        Bt_Clear2.Enabled = False

        text_num3.Enabled = False
        Bt_Clear3.Enabled = False

        'End of disable all textbox and clear buttons after Calculate button was pressed

    End Sub

    'End of caculation session


    'Function to clear individuals textbox

    Private Sub Bt_Clear1_Click(sender As Object, e As EventArgs) Handles Bt_Clear1.Click
        text_num1.Clear()
        num1 = Nothing
    End Sub

    Private Sub Bt_Clear2_Click(sender As Object, e As EventArgs) Handles Bt_Clear2.Click
        text_num2.Clear()
        num2 = Nothing
    End Sub

    Private Sub Bt_Clear3_Click(sender As Object, e As EventArgs) Handles Bt_Clear3.Click
        text_num3.Clear()
        num3 = Nothing
    End Sub

    'End of function to clear individuals textbox

    'Messagebox button
    Private Sub bt_about_Click(sender As Object, e As EventArgs) Handles bt_about.Click

        MsgBox("Program design by Edino - W0430397")

    End Sub

    'End of messagebox button

    'Function to clear all textbox
    Private Sub B_Reset_Click_1(sender As Object, e As EventArgs) Handles B_Reset.Click

        text_num1.Text = ""
        text_num2.Text = ""
        text_num3.Text = ""
        Tx_Average.Clear()
        CalcAverage = Nothing
        Tx_Average.BackColor = Color.White
        Label_Average.BackColor = Color.FromKnownColor(KnownColor.Control)
        Tx_Average.Enabled = False
        num1 = Nothing
        num2 = Nothing
        num3 = Nothing

        text_num1.Enabled = True
        Bt_Clear1.Enabled = True

        text_num2.Enabled = False
        Bt_Clear2.Enabled = False

        text_num3.Enabled = False
        Bt_Clear3.Enabled = False

        LabelCalcAverage.Enabled = False


        'Application.Restart() 'Another way to reset all TextBoxes but this one restart the application

    End Sub

    'End of function to clear all TextBoxes

End Class

Answer 1

Thank you for the help. I have adjusted my code and now it's working in the way I wanted. Here is my code:

Public Class MainWindowApp
    '------------------------------------------------------------------------------------------------------------------------------------------
    'Program Info
    '------------------------------------------------------------------------------------------------------------------------------------------
    'Program:   Calculate the Average - Windows Forms
    'Date:      10/10/2018
    'Author:    Edino de Souza
    'Operation: This application will prompt the user for 3 numbers and calculate the average following somes rules and display to the user, 
    'also when show the average it will show In red If the average Is less than 60 and green if is equal or greater than 60.
    'Rules to follow: 
    '   a) The user must provide a value each edit box.
    '   b) The user must provide a number.
    '   c) The user must provide a value not Less than 0 and not greater than 100.
    'If the value won't falls under one of the conditions above, the user will get messageboxes with each error.
    '   For example:  
    '               MsgBox("Please insert a value on TextBox1")
    '               MsgBox("Please insert a number on TextBox1")
    '               MsgBox("Please insert a number greater than zero on TextBox1")
    '               MsgBox("Please insert a number less than one hundred on TextBox1")
    '               
    '------------------------------------------------------------------------------------------------------------------------------------------
    'Change Log
    '------------------------------------------------------------------------------------------------------------------------------------------
    'Date               Programmer          Change
    '------------------------------------------------------------------------------------------------------------------------------------------
    '10/10/2018         Edino de Souza      Initial/Final Version
    '10/15/2018         Edino de Souza      Adjusted reset button to reset variables too.
    '10/17/2018         Edino de Souza      First part of the addition of the IF statements
    '10/17/2018         Edino de Souza      Adjusted the code to perform what is required.
    '10/21/2018         Edino de Sozua      Correction of the MSGBOX showing on reset button and added a better description of the operation.
    '------------------------------------------------------------------------------------------------------------------------------------------


    'Begin of Variables Session

    Public num1 As Decimal
    Public num2 As Decimal
    Public num3 As Decimal
    Public CalcAverage As Decimal
    Public doNotShowMsgBox As Boolean 'This variable is used to enable or disable the validations part of the code to avoid MSGBOX.


    'End of Variables Session


    'Begin of Input Session 1 with validations

    Private Sub text_num1_TextChanged(sender As Object, e As EventArgs) Handles text_num1.TextChanged

        'TextBox and Clear button controlling.

        text_num1.Enabled = True    'Enable textbox 1
        Bt_Clear1.Enabled = True    'Enable clear button 1

        text_num2.Enabled = False   'Disable textbox 2
        Bt_Clear2.Enabled = False   'Enable clear button 2

        text_num3.Enabled = False   'Disable textbox 3
        Bt_Clear3.Enabled = False   'Disable button 3

        LabelCalcAverage.Enabled = False    'Disable the calculator button
        Tx_Average.Enabled = False      'Disable the average textbox

        'End - TextBox and Clear button controlling.


        'Section to verify if all the conditions were satisfied.

        If doNotShowMsgBox = False Then

            If text_num1.Text = Nothing Then
                MsgBox("Please insert a value on TextBox1")
                text_num2.Enabled = False

                doNotShowMsgBox = True

                text_num1.Clear()

                doNotShowMsgBox = False


            ElseIf IsNumeric(text_num1.Text) = False Then
                MsgBox("Please insert a number on TextBox1")
                text_num2.Enabled = False

                doNotShowMsgBox = True

                text_num1.Clear()

                doNotShowMsgBox = False


            ElseIf (text_num1.Text) < 0 Then
                MsgBox("Please insert a number greater than zero on TextBox1")
                text_num2.Enabled = False

                doNotShowMsgBox = True

                text_num1.Clear()

                doNotShowMsgBox = False


            ElseIf (text_num1.Text) > 100 Then

                MsgBox("Please insert a number less than one hundred on TextBox1")
                text_num2.Enabled = False

                doNotShowMsgBox = True

                text_num1.Clear()

                doNotShowMsgBox = False

            Else

                Decimal.TryParse(text_num1.Text, num1)

                text_num2.Enabled = True    'Enable textbox 2 after all validations
                Bt_Clear2.Enabled = True    'Enable textbox 2 clear button after all validations

            End If

        ElseIf doNotShowMsgBox = True Then 'Won't execute validations part when active.

        End If


        'End - Section to verify if all the conditions were satisfied.


    End Sub

    'End of Input Session 1 with validations

    'Begin of Input Session 2 with validations

    Private Sub text_num2_TextChanged(sender As Object, e As EventArgs) Handles text_num2.TextChanged


        If doNotShowMsgBox = False Then

            If text_num2.Text = Nothing Then
                MsgBox("Please insert a value on TextBox2")
                text_num3.Enabled = False

                doNotShowMsgBox = True

                text_num2.Clear()

                doNotShowMsgBox = False


            ElseIf IsNumeric(text_num2.Text) = False Then
                MsgBox("Please insert a number on TextBox2")
                text_num3.Enabled = False

                doNotShowMsgBox = True

                text_num2.Clear()

                doNotShowMsgBox = False

            ElseIf (text_num2.Text) < 0 Then
                MsgBox("Please insert a number greater than zero on TextBox2")
                text_num3.Enabled = False

                doNotShowMsgBox = True

                text_num2.Clear()

                doNotShowMsgBox = False

            ElseIf (text_num2.Text) > 100 Then

                MsgBox("Please insert a number less than one hundred on TextBox2")
                text_num3.Enabled = False

                doNotShowMsgBox = True

                text_num2.Clear()

                doNotShowMsgBox = False

            Else

                Decimal.TryParse(text_num2.Text, num2)

                text_num3.Enabled = True    'Enable textbox 3 after all validations
                Bt_Clear3.Enabled = True    'Enable textbox 3 clear button after all validations

            End If

        ElseIf doNotShowMsgBox = True Then 'Won't execute validations part when active.

        End If


    End Sub


    'End of Input Session 2


    'Begin of Input Session 3 with validations

    Private Sub text_num3_TextChanged(sender As Object, e As EventArgs) Handles text_num3.TextChanged

        If doNotShowMsgBox = False Then

            If text_num3.Text = Nothing Then
                MsgBox("Please insert a value on TextBox3.")

                doNotShowMsgBox = True

                text_num3.Clear()

                doNotShowMsgBox = False

            ElseIf IsNumeric(text_num3.Text) = False Then
                MsgBox("Please insert a number")

                doNotShowMsgBox = True

                text_num3.Clear()

                doNotShowMsgBox = False

            ElseIf (text_num3.Text) < 0 Then
                MsgBox("Please insert a number greater than zero on TextBox3")

                doNotShowMsgBox = True

                text_num3.Clear()

                doNotShowMsgBox = False

            ElseIf (text_num3.Text) > 100 Then

                MsgBox("Please insert a number less than one hundred on TextBox3")

                doNotShowMsgBox = True

                text_num3.Clear()

                doNotShowMsgBox = False

            Else

                Decimal.TryParse(text_num3.Text, num3)
                LabelCalcAverage.Enabled = True     'Enable the calculator button only after all fields were filled

            End If

        ElseIf doNotShowMsgBox = True Then 'Won't execute validations part when active.

        End If


    End Sub


    'End of Input Session 3


    'Caculation session
    Private Sub LabelCalcAverage_Click(sender As Object, e As EventArgs) Handles LabelCalcAverage.Click

        CalcAverage = (num1 + num2 + num3) / 3

        Tx_Average.Enabled = True


        'Function to show different colors on TextBox and Label

        If CalcAverage < 60 Then
            Tx_Average.ForeColor = Color.Yellow

            Tx_Average.BackColor = Color.Red

            Label_Average.BackColor = Color.Red

            Tx_Average.Text = CalcAverage.ToString("###.##")

        ElseIf CalcAverage >= 60 Then
            Tx_Average.ForeColor = Color.Yellow

            Tx_Average.BackColor = Color.Green

            Label_Average.BackColor = Color.Green

            Tx_Average.Text = CalcAverage.ToString("###.##")

        End If

        'End of function to show different colors on TextBox and Label


        'Disable all textbox and clear buttons after Calculate button was pressed

        text_num1.Enabled = False
        Bt_Clear1.Enabled = False

        text_num2.Enabled = False
        Bt_Clear2.Enabled = False

        text_num3.Enabled = False
        Bt_Clear3.Enabled = False

        'End of disable all textbox and clear buttons after Calculate button was pressed

    End Sub

    'End of caculation session


    'Function to clear individuals textbox

    Private Sub Bt_Clear1_Click(sender As Object, e As EventArgs) Handles Bt_Clear1.Click

        doNotShowMsgBox = True

        text_num1.Clear()
        num1 = Nothing

        doNotShowMsgBox = False

    End Sub

    Private Sub Bt_Clear2_Click(sender As Object, e As EventArgs) Handles Bt_Clear2.Click

        doNotShowMsgBox = True

        text_num2.Clear()
        num2 = Nothing

        doNotShowMsgBox = False

    End Sub

    Private Sub Bt_Clear3_Click(sender As Object, e As EventArgs) Handles Bt_Clear3.Click

        doNotShowMsgBox = True

        text_num3.Clear()
        num3 = Nothing

        doNotShowMsgBox = False

    End Sub

    'End of function to clear individuals textbox

    'Messagebox button
    Private Sub bt_about_Click(sender As Object, e As EventArgs) Handles bt_about.Click

        MsgBox("Program design by Edino - W0430397")

    End Sub

    'End of messagebox button

    'Function to clear all textbox
    Private Sub B_Reset_Click_1(sender As Object, e As EventArgs) Handles B_Reset.Click

        doNotShowMsgBox = True

        text_num1.Clear()
        num1 = Nothing

        text_num2.Clear()
        num2 = Nothing

        text_num3.Clear()
        num3 = Nothing

        doNotShowMsgBox = False

        Tx_Average.Clear()
        CalcAverage = Nothing
        Tx_Average.BackColor = Color.White
        Label_Average.BackColor = Color.FromKnownColor(KnownColor.Control)
        Tx_Average.Enabled = False

        text_num1.Enabled = True
        Bt_Clear1.Enabled = True

        text_num2.Enabled = False
        Bt_Clear2.Enabled = False

        text_num3.Enabled = False
        Bt_Clear3.Enabled = False

        LabelCalcAverage.Enabled = False


        'Application.Restart() 'Another way to reset all textbox but this one restart the application

    End Sub

    'End of function to clear all textbox

End Class

Answer 2

Move you validating code to the Validating event of the TextBox.

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
        TextBox2.Clear()
        'No MessageBox appears
End Sub

Private Sub TextBox2_Validating(sender As Object, e As System.ComponentModel.CancelEventArgs) Handles TextBox2.Validating
        MessageBox.Show("Validating")
End Sub