PropertyChanged事件总是空 [英] PropertyChanged event always null

问题描述

我有以下的（略）XAML：

I have the following (abbreviated) xaml:

<TextBlock Text="{Binding Path=statusMsg, UpdateSourceTrigger=PropertyChanged}"/>

我有一个单例类：

I have a singleton class:

public class StatusMessage : INotifyPropertyChanged
{   
    private static StatusMessage instance = new StatusMessage();

    private StatusMessage() { }

    public static StatusMessage GetInstance()
    {
        return instance;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(string status)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(status));
        }
    }

    private string statusMessage;
    public string statusMsg
    {
        get
        {
            return statusMessage;
        }
        set
        {
            statusMessage = value;
            OnPropertyChanged("statusMsg");
        }
    }
}

在我的主窗口的构造函数：

And in my main window constructor:

StatusMessage testMessage = StatusMessage.GetInstance();
testMessage.statusMsg = "This is a test msg";    

我不能得到的文本块以显示测试消息。当我通过调试监控code时，的PropertyChanged始终为空。任何想法？

I cannot get the textblock to display the test message. When I monitor the code through debug, the PropertyChanged is always null. Any ideas?

推荐答案

感谢杰罗姆！一旦我设定在DataContext它开始工作，因为它应该！添加以下到主窗口的构造函数用于测试目的：

Thanks Jerome! Once I set the DataContext it started working as it should! I added the following to the main window constructor for testing purposes:

 this.DataContext = testMessage;

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