PropertyChanged 事件始终为空 [英] PropertyChanged event always null

问题描述

我有以下(缩写)xaml:

I have the following (abbreviated) xaml:

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

我有一个单例类:

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");
        }
    }
}

在我的主窗口构造函数中:

And in my main window constructor:

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

我无法使用文本块来显示测试消息.当我通过调试监视代码时，PropertyChanged 始终为空.有什么想法吗?

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

谢谢 Jerome！一旦我设置了 DataContext，它就开始正常工作了！出于测试目的，我将以下内容添加到主窗口构造函数中:

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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