2

我遇到了一个问题，无法找到 INotifyPropertyChanged、PropertyChangedEventHandler 和 PropertyEventChangedArgs：

“找不到类型或命名空间名称‘PropertyChangedEventArgs’（您是否缺少 using 指令或程序集引用？）”

C＃：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WhackaMole_MVVM
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            DataContext = new WhackAMoleViewModel();
        }
    }

    public class WhackAMoleViewModel : PropertyChangedBase
    {
        private List<Mole> _moles;
        public List<Mole> Moles
        {
            get { return _moles; }
        }

        private System.Threading.Timer timer;
        private System.Random random = new Random();

        public WhackAMoleViewModel()
        {
            _moles = Enumerable.Range(1, 9).Select(x => new Mole()).ToList();
            timer = new Timer(x => RaiseRandomMole(), null, 0, 300);
        }

        private void RaiseRandomMole()
        {
            //If random number is less than 5 skip this iteration
            if (random.Next(1, 10) > 5)
                return;

            //Choose a random mole
            var mole = Moles[random.Next(0, 8)];

            //If it's already raised, do nothing
            if (mole.IsUp)
                return;

            //Raise it
            mole.IsUp = true;

            //Then Get it down somewhere between 1 and 2 seconds after
            Task.Factory.StartNew(() => Thread.Sleep(random.Next(1000, 2000)))
                        .ContinueWith(x => mole.IsUp = false);
        }
    }


    public class Mole : PropertyChangedBase
    {
        private bool _isUp;
        public bool IsUp
        {
            get { return _isUp; }
            set
            {
                _isUp = value;
                OnPropertyChanged("IsUp");
            }
        }
    }

    public class PropertyChangedBase : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged(string propertyName)
        {
            Application.Current.Dispatcher.BeginInvoke((Action)(() =>
            {
                PropertyChangedEventHandler handler = PropertyChanged;
                if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
            }));
        }
    }
}

XAML：

<Window x:Class="WhackaMole_MVVM.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <ItemsControl ItemsSource="{Binding Moles}">
        <ItemsControl.ItemsPanel>
            <ItemsPanelTemplate>
                <UniformGrid Rows="3" Columns="3" IsItemsHost="True"/>
            </ItemsPanelTemplate>
        </ItemsControl.ItemsPanel>
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <Image x:Name="Mole" Height="0" Width="100" 
                       Source="C:\Users\MonAmi\Documents\Visual Studio 2012\Projects\WhackaMole\WhackaMole\mole2.png"
                       Stretch="Fill"
                       VerticalAlignment="Bottom"/>
                <DataTemplate.Triggers>
                    <DataTrigger Binding="{Binding IsUp}" Value="True">
                        <DataTrigger.EnterActions>
                            <BeginStoryboard>
                                <Storyboard TargetName="Mole">
                                    <DoubleAnimation Storyboard.TargetProperty="Height" 
                                                     From="0" To="77"
                                                     Duration="00:00:00.3"/>
                                </Storyboard>
                            </BeginStoryboard>
                        </DataTrigger.EnterActions>
                        <DataTrigger.ExitActions>
                            <BeginStoryboard>
                                <Storyboard TargetName="Mole">
                                    <DoubleAnimation Storyboard.TargetProperty="Height"
                                                     From="77" To="0"
                                                     Duration="00:00:00.3"/>
                                </Storyboard>
                            </BeginStoryboard>
                        </DataTrigger.ExitActions>
                    </DataTrigger>
                </DataTemplate.Triggers>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
</Window>
4

1 回答 1

7

编译器绝对正确。你需要：

using System.ComponentModel;

...在您的using指令中，就像PropertyChangedEventArgs在该名称空间中一样。（当然，或者你可以完全限定对它的每一个引用。）

每当您收到此错误消息时要做的第一件事就是找出相关类型所在的命名空间和程序集，并检查您的using指令和程序集引用......就像编译器消息所暗示的那样，基本上。

于 2013-05-17T16:42:22.203 回答