Android 可以在MvvmCross中执行

我正在开发一个Xamarin.Android应用程序，我正在使用MvvmCross。此处我的代码

中的DecreaseCommand

不起作用：

public class CartItemViewModel : MvxNotifyPropertyChanged
{      
    private int quantity = 0;      

    public CartItemViewModel()
    {
        IncreaseCommand = new MvxCommand(ExecuteIncreaseCommand, CanExecuteIncreaseCommand);
        DecreaseCommand = new MvxCommand(ExecuteDecreaseCommand, CanExecuteDecreaseCommand);
        Delete = new MvxCommand (() => {Quantity++;});
    }        

    public int Quantity
    {
        get { return quantity; }
        set
        {
            quantity = value;
            RaisePropertyChanged("Quantity");
            RaisePropertyChanged("SubTotal");
        }
    }

    public ICommand IncreaseCommand { get; set; }
    public ICommand DecreaseCommand { get; set; }
    public ICommand Delete { get; set; }


    private void ExecuteIncreaseCommand()
    {
         Quantity++;
    }

    private bool CanExecuteIncreaseCommand()
    {
        return true;
    }

    private void ExecuteDecreaseCommand()
    {
        Quantity--;
    }

    private bool CanExecuteDecreaseCommand()
    {
        return Quantity > 0;
    }


}

---

我怀疑

CanExecuteDecreaseCommand

没有启动，这段代码可能有什么问题？

当您更新

Quantity

属性时，您忘记调用

RaiseCanecuteChanged

另外，您不需要设置总是返回true的

CanExecute

：

public class CartItemViewModel : MvxNotifyPropertyChanged
{      
    private int quantity = 0;      

    public CartItemViewModel()
    {
        IncreaseCommand = new MvxCommand(ExecuteIncreaseCommand);
        DecreaseCommand = new MvxCommand(ExecuteDecreaseCommand, CanExecuteDecreaseCommand);
        Delete = new MvxCommand (() => {Quantity++;});
    }        

    public int Quantity
    {
        get { return quantity; }
        set
        {
            quantity = value;
            RaisePropertyChanged("Quantity");
            RaisePropertyChanged("SubTotal");
            DecreaseCommand.RaiseCanExecuteChanged();
        }
    }

    public IMvxCommand IncreaseCommand { get; set; }
    public IMvxCommand DecreaseCommand { get; set; }
    public IMvxCommand Delete { get; set; }


    private void ExecuteIncreaseCommand()
    {
         Quantity++;
    }

    private void ExecuteDecreaseCommand()
    {
        Quantity--;
    }

    private bool CanExecuteDecreaseCommand()
    {
        return Quantity > 0;
    }
}

---

你是怎么装订的？Increase命令有效吗？是Increasecommand有效。当我在CanExecutedCreasCommand（）中放入{return true}时，它工作正常。但当我放入{Quantity！=0}时，它不工作，但会弹出错误，System.Windows.Input.ICommand不包含RaisCanExecuteChanged（）的定义我已将ICommand更改为IMvxCommand，它可以正常工作。非常感谢。@wiliam Barbosa