C# 无法在静态上下文中访问非静态方法？
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Cannot access non-static method in static context?
提问by Isaiah Nelson
Given this code....
鉴于此代码....
public class CalibrationViewModel : ViewModelBase
{
private FileSystemWatcher fsw;
public CalibrationViewModel(Calibration calibration)
{
fsw = new FileSystemWatcher
{
Path = @"C:\Users\user\Desktop\Path\ToFile\Test_1234.txt",
Filter = @"Test_1234.txt",
NotifyFilter = NotifyFilters.LastWrite
};
fsw.Changed += (o, e) =>
{
var lastLine = File.ReadAllLines(e.FullPath).Last();
Dispatcher.BeginInvoke((Action<string>) WriteLineToSamplesCollection, lastLine); //line that cites error
};
}
private void WriteLineToSamplesCollection(string line)
{
// do some work
}
}
Why am I getting the error, 'Cannot access non-static method BeginInvoke in static context'?
为什么我会收到错误消息“无法在静态上下文中访问非静态方法 BeginInvoke”？
I have looked at several other examples on SE and most cite trying to use a field before the object is created as if they were trying to use a non-static field in a static manner, but I don't understand what it is about my code that is invoking the same error.
我在 SE 上查看了其他几个示例，并且大多数引用尝试在创建对象之前使用字段，就好像他们试图以静态方式使用非静态字段一样，但我不明白这与我的调用相同错误的代码。
Lastly, what can I do to fix this specific issue/code?
最后，我能做些什么来解决这个特定的问题/代码？
Update: Fixed title to reflect issue with a 'method' and not a 'property'. I also added that the class implements ViewModelBase.
更新：修正标题以反映“方法”而非“属性”的问题。我还补充说该类实现了 ViewModelBase。
采纳答案by Federico Berasategui
If this is WPF, System.Windows.Threading.Dispatcherdoes not have a static BeginInvoke()method.
如果这是WPF，System.Windows.Threading.Dispatcher则没有静态BeginInvoke()方法。
If you want to call that statically (this is, without having a reference to the Dispatcher instance itself), you may use the static Dispatcher.CurrentDispatcherproperty:
如果你想静态调用它（这是，没有对 Dispatcher 实例本身的引用），你可以使用静态Dispatcher.CurrentDispatcher属性：
Dispatcher.CurrentDispatcher.BeginInvoke(...etc);
Be aware though, that doing this from a background thread will NOT return a reference to the "UI Thread"'s Dispatcher, but instead create a NEW Dispatcher instance associated with the said Background Thread.
但请注意，从后台线程执行此操作不会返回对“UI 线程”的 Dispatcher 的引用，而是创建与所述后台线程关联的新 Dispatcher 实例。
A more secure way to access the "UI Thread"'s Dispatcher is via the use of the System.Windows.Application.Currentstatic property:
访问“UI 线程”的 Dispatcher 的一种更安全的方法是使用System.Windows.Application.Current静态属性：
Application.Current.Dispatcher.BeginInvoke(...etc);
回答by Craig Shearer
It's because Dispatcheris a class not a property. Shouldn't you be making your CalibrationViewModelclass a subclass of some other class which has a Dispatcherproperty?
这是因为Dispatcher是一个类而不是一个属性。你不应该让你的CalibrationViewModel类成为其他有Dispatcher属性的类的子类吗？
回答by Mike Perrenoud
Change this:
改变这个：
Dispatcher.BeginInvoke
to this:
对此：
Dispatcher.CurrentDispatcher.BeginInvoke
the issue is BeginInvokeis an instance method and needs an instance to access it. However, your current syntax is trying to access BeginInvokein a staticmanner off the class Dispatcherand that's what's causing this error:
问题是BeginInvoke一个实例方法，需要一个实例来访问它。但是，您当前的语法试图以类外BeginInvoke的static方式访问，Dispatcher这就是导致此错误的原因：
Cannot access non-static method BeginInvoke in static context
无法在静态上下文中访问非静态方法 BeginInvoke
