VB.NET按钮点击事件代码异常求助：Label1非空却显示Label16内容

你遇到的核心问题是即便Label1有有效内容，程序依然会显示Label16的内容，这是因为代码里的逻辑表达式运算符优先级处理错误，导致条件判断完全偏离了你的预期。

问题根源拆解 #

来看这段出问题的条件判断：

If city = False And Label16.Text = "" Or Label16.Text = " " Then

在VB.NET中，And的优先级高于Or，所以这个表达式会被编译器解析成：

(city = False And Label16.Text = "") Or Label16.Text = " "

这意味着只要Label16.Text是空格（不管city的值是什么），整个条件就会成立。后续的sss = True又会覆盖Location1的值，最终导致Label16的内容被显示，完全忽略了Label1的状态。

修复方案 #

只需要给Or的两个子条件加上括号，明确逻辑分组，让程序先判断Label16是否为空/空格，再和city=False做逻辑与：

If city = False And (Label16.Text = "" Or Label16.Text = " ") Then

代码优化建议（可选） #

为了让代码更简洁、可读性更强，还可以做这些改进：

1. 用String.IsNullOrWhiteSpace()替代手动判断空/空格，更可靠且代码更短
2. 给变量起有意义的名字，比如把sss改成useLabel16Content，city改成hasValidCityFromLabel1
3. 合并重复的TextBox1.Text = ""语句
4. 使用字符串插值（$""）替代字符串拼接，提升可读性和性能

修复后的完整代码 #

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    Dim locationResult As String
    Dim hasValidCityFromLabel1 As Boolean
    Dim useLabel16Content As Boolean

    If Not IsNumeric(TextBox1.Text) Then
        MsgBox("Invalid ip address")
    Else
        hasValidCityFromLabel1 = True
        useLabel16Content = False
        geoip()

        ' 检查Label1是否包含有效内容
        hasValidCityFromLabel1 = Not String.IsNullOrWhiteSpace(Label1.Text)
        If hasValidCityFromLabel1 Then
            locationResult = Label1.Text
        End If

        ' 当Label1无有效内容，且Label16为空时，使用Label17；否则标记使用Label16
        If Not hasValidCityFromLabel1 And String.IsNullOrWhiteSpace(Label16.Text) Then
            locationResult = Label17.Text
        Else
            useLabel16Content = True
        End If

        ' 如果标记使用Label16，则覆盖结果
        If useLabel16Content Then
            locationResult = Label16.Text
        End If
    End If

    TextBox1.Text = ""

    ' 生成对应消息到TextBox2
    If CheckBox2.Checked Then
        TextBox2.Text = $"We look forward to meet you tomorrow at the meeting place at 1 PM, the package has been shipped already to you to {locationResult}. If you wont be there for completing the transaction, we will need to proceed to stage 2."
    End If

    If CheckBox1.Checked Then
        TextBox2.Text = $"My name is {TextBox3.Text} from {TextBox4.Text} and im here for letting you know that we look forward to meet you tomorrow at the meeting place at 1 PM, the package has been shipped already to you to {locationResult}. If you wont be there for completing the transaction, we will need to proceed to stage 2."
    End If
End Sub

内容的提问来源于stack exchange，提问作者z a