C# 静态成员在构造函数中初始化后获取 null

Question

我有一个 class 保存静态 ImageSource 对象，这些对象以后经常被其他 classes:

public class ImagePrepare
{
    public static readonly ImageSource m_imageGreen;
    public static readonly ImageSource m_imageYellow;
    public static readonly ImageSource m_imageRed;
    public static readonly ImageSource m_imagePurple;

    public static int iTest;

    //static Constructor
    static ImagePrepare()
    {
        iTest = 2;

        Uri uriImage = new Uri("pack://application:,,,/" + Assembly.GetExecutingAssembly().GetName().Name + ";component/" + "Ressourcen/Button_Green.png", UriKind.Absolute);
        ImageSource m_imageGreen = new BitmapImage(uriImage);

        uriImage = new Uri("pack://application:,,,/" + Assembly.GetExecutingAssembly().GetName().Name + ";component/" + "Ressourcen/Button_Yellow.png", UriKind.Absolute);
        ImageSource m_imageYellow = new BitmapImage(uriImage);

        uriImage = new Uri("pack://application:,,,/" + Assembly.GetExecutingAssembly().GetName().Name + ";component/" + "Ressourcen/Button_Red.png", UriKind.Absolute);
        ImageSource m_imageRed = new BitmapImage(uriImage);

        uriImage = new Uri("pack://application:,,,/" + Assembly.GetExecutingAssembly().GetName().Name + ";component/" + "Ressourcen/Button_Purple.png", UriKind.Absolute);
        ImageSource m_imagePurple = new BitmapImage(uriImage);
    }

    public static ImageSource GetImageSource()
    {
        return m_imageGreen;
    }
}

现在，例如，当我从 MainWindow class 调用 ImagePrepare.GetImageSource() 时，首先调用静态 ctor 并且所有静态成员都按预期正确初始化。
然后调用 GetImageSource()，但在调试此函数时，成员 m_imageGreen 为空！
我在这里错过了什么？
成员 iTest 的行为与预期一致，并且仍然保持其值 2。

Answer 1

在您的静态构造函数中，您将静态成员重载为本地成员。

通过调用：

ImageSource m_imageGreen = new BitmapImage(uriImage);

您实际上创建了一个新的局部变量，而不是引用静态变量。这样做：

m_imageGreen = new BitmapImage(uriImage);

C# 静态成员在构造函数中初始化后获取 null

C# static member gets null after init in Contructor

c#

static

bitmapimage