爲什麼不能從靜態上下文中引用方法定義？

Question

無法從靜態上下文訪問非靜態方法AddNew。

引用的類：

public class RelayCommand : ICommand 
{ 
    public RelayCommand(Action<object> execute); 
    public RelayCommand(Action execute); 
    public RelayCommand(Action execute, Func<bool> canExecute); 
    public RelayCommand(Action<object> execute, Predicate<object> canExecute); 
    public bool CanExecute(object parameter); 
    public void Execute(object parameter); 
    public event EventHandler CanExecuteChanged; 
} 

    [TypeForwardedFrom("PresentationCore, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35")] 
    [TypeConverter("System.Windows.Input.CommandConverter, PresentationFramework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, Custom=null")] 
    [ValueSerializer("System.Windows.Input.CommandValueSerializer, PresentationFramework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, Custom=null")] 
    public interface ICommand 
    { 
    /// <summary>Defines the method that determines whether the command can execute in its current state.</summary> 
    /// <returns>true if this command can be executed; otherwise, false.</returns> 
    /// <param name="parameter">Data used by the command. If the command does not require data to be passed, this object can be set to null.</param> 
    bool CanExecute(object parameter); 
    /// <summary>Defines the method to be called when the command is invoked.</summary> 
    /// <param name="parameter">Data used by the command. If the command does not require data to be passed, this object can be set to null.</param> 
    void Execute(object parameter); 
    /// <summary>Occurs when changes occur that affect whether or not the command should execute.</summary> 
    event EventHandler CanExecuteChanged; 
    } 

我的代碼：

public class ExampleViewModel: NotificationObject 
{ 

    public ICommand AddNewCommand { get; } = new Microsoft.Practices.Prism.Commands.DelegateCommand(AddNew, CanAdd); // method references arn't static?? 

    public String NewName { get; set; } = ""; 

    internal bool CanAdd() 
    { 
     //Can Add if string is non empty & non null 
     return !string.IsNullOrEmpty(NewName); 
    } 

    internal void AddNew() 
    { 
     var name = NewName ?? "NeedToCheckforNull"; 

     var newWindSpeedEnv = new WindSpeedEnvelope() 
     { 
      Id = Guid.NewGuid(), 
      Name = name 
     }; 
    } 
} 

從Java的到來，我本來期望這個工作，因爲這些方法是衆所周知的，在編譯時靜態存在嗎？

Answer 1

只是初始化DelegateCommand在ExampleViewModel構造：

public ExampleViewModel() 
{ 
    AddNewCommand = new DelegateCommand(AddNew, CanAdd); 
} 

public ICommand AddNewCommand { get; private set; } 

作爲一個側面說明，NewName永遠不會計算爲NULL因爲你給它的string.Empty的值，所以空合併運算符不在那裏做任何事。