Windows 如何使用StorageFolder变量类型创建新对象？

因此，我有一个错误对象引用没有设置为对象的实例

以下是发生错误的区域：

private async void Savebutton_click(object sender, RoutedEventArgs e)
{
    string recipename = recipenametextbox.Text.ToString();
    string recipemethod = methodtextbox.Text.ToString();
    string recipeingredients = ingredientstextbox.Text.ToString();

    //File names.
    string recipenamefilename = recipename + "title.txt";
    string recipemethodfilename = recipename + "method.txt";
    string recipeingredientsfilename = recipename + "ingredients.txt";

    await currentrecipe.folder.CreateFolderAsync(recipename);

    await currentrecipe.folder.CreateFileAsync(recipenamefilename);
    File.WriteAllText(recipenamefilename, recipename);

    await currentrecipe.folder.CreateFileAsync(recipemethodfilename);
    File.WriteAllText(recipemethodfilename, recipemethod);

    await currentrecipe.folder.CreateFileAsync(recipeingredientsfilename);
    File.WriteAllText(recipeingredientsfilename, recipeingredients);

    //Clear currentrecipe ready for next recipe.
    currentrecipe.folder = null;
    currentrecipe.Picturefile = null;
    currentrecipe.recipebackgroundcolourenabled = false;
}

---

我认为这与初始化currentrecipe变量的StorageFolder成员有关currentrecipe是一个recipie变量。此外，我不认为这是与NullReferenceException问题的重复，因为我知道NullReferenceException是什么，我知道如何以某种方式修复它，但我不知道如何修复这个特定的NullReferenceException-存储文件夹。该错误也发生在Wait currentrecipe.folder.CreateFolderAsyncrecipename上

这是我的recipie课程：

---

正如你所说，错误发生在

await currentrecipe.folder.CreateFolderAsync(recipename)

我首先检查currentrecipe和folder是否都已初始化：

if (currentrecipe != null)
{
    if (currentrecipe.folder != null)
    {
        await currentrecipe.folder.CreateFolderAsync(recipename)
    }
    else
    {
        Console.Write("currentrecipe.folder is null")
    }
}   
else
{
    Console.Write("currentrecipe is null")
}

---

至少从这一点开始，否则可能是CreateFolderAsync返回null。

可能的重复应该在函数顶部添加一个断点，一次一行地遍历它，这样你就可以准确地看到null引用发生在哪一行。我不认为它是重复的，这仅仅是因为我知道NullReferenceException是什么，并且我知道如何以某种方式修复它，但我不知道如何修复存储文件夹的这个特定NullReferenceException。该错误也发生在Wait currentrecipe.folder.CreateFolderAsyncrecipename上@托比

if (currentrecipe != null)
{
    if (currentrecipe.folder != null)
    {
        await currentrecipe.folder.CreateFolderAsync(recipename)
    }
    else
    {
        Console.Write("currentrecipe.folder is null")
    }
}   
else
{
    Console.Write("currentrecipe is null")
}