Question

我确信这很简单，但我无法弄明白，也没有找到答案，我正在检查NumericUpDown数组中的对象是否为null （PrimaryWeightsValueChanged()由valueChange事件调用，在表单加载之前它们应该为null） 但问题是，即使在控件初始化并具有值
之后，条件也始终返回true 我做错了什么？

private NumericUpDown[] PrimaryWeightNumsAr = {
num_Primary_Billing,
num_Primary_Rutine,
num_Primary_Seker,
num_Primary_Sla
};
private void PrimaryWeightsValueChanged()
{
    // even when NumericUpDown`s are not null it enters here
    if (PrimaryWeightNumsAr.AsEnumerable().Any(x => x == null))
        return;

    // doing stuff when not null...
}

visual basic version：

Private PrimaryWeightNumsAr() As NumericUpDown = {num_Primary_Billing, num_Primary_Rutine, num_Primary_Seker, num_Primary_Sla}
Private Sub PrimaryWeightsValueChanged()
    ' even when NumericUpDown`s are not null it enters here '
    If PrimaryWeightNumsAr.AsEnumerable().Any(Function(x) x Is Nothing) Then Exit Sub

    If PrimaryWeightNumsAr.AsEnumerable().Sum(Function(x) x.Value) <> 100 Then
        For Each itm As NumericUpDown In PrimaryWeightNumsAr
            itm.BackColor = GuiProfile.sys_red
        Next
    Else
        For Each itm As NumericUpDown In PrimaryWeightNumsAr
            itm.BackColor = Color.SpringGreen
        Next
    End If
End Sub

Answer 1

（对于未来的观众）

根据@Ivan Stoev的评论，问题解决了。
＆＃34;因为字段初始化程序在类构造函数之前运行＆＃34; 换句话说，我的数组是在对象初始化之前声明的
在初始化数组后（在调用InitializeComponent()之后的构造函数内）将NumericUpdowns添加到数组中就可以了。这是概括的固定代码：

Public Class PerformanceForm

    Sub New()
        ' This call is required by the designer. '
        InitializeComponent()
        ' Add any initialization after the InitializeComponent() call. '
        PrimaryWeightNumsAr = {num_Primary_Billing, num_Primary_Rutine, num_Primary_Seker, num_Primary_Sla}
    End Sub
    Private PrimaryWeightNumsAr() As NumericUpDown

    Private Sub PrimaryWeightsValueChanged()

        If PrimaryWeightNumsAr Is Nothing Then Exit Sub
        ' do other stuff... '

    End Sub

End Class

C＃版本：

public class PerformanceForm
{

    public PerformanceForm()
    {
        // This call is required by the designer. 
        InitializeComponent();
        // Add any initialization after the InitializeComponent() call. 
        PrimaryWeightNumsAr = {
            num_Primary_Billing,
            num_Primary_Rutine,
            num_Primary_Seker,
            num_Primary_Sla
        };
    }

    private NumericUpDown[] PrimaryWeightNumsAr;
    private void PrimaryWeightsValueChanged()
    {

        if (PrimaryWeightNumsAr == null)
            return;
        // do other stuff... 

    }

}

使用LINQ在对象数组中搜索空对象

1 个答案:

（对于未来的观众）