System.StackOverflowException WPF MVVM [英] System.StackOverflowException WPF MVVM

问题描述

我正在尝试使用 MVVM 在 WPF 中创建一个简单的数字时钟.我有一个带有绑定的标签.背后的代码很简单，每秒引发一个属性更改事件，我有一个 stackoverflow 异常.有人可以帮忙吗?

I am trying to create a simple digital clock in WPF using MVVM. I have a label which has a binding. The code behind is simple simple and raising a property changed event each second and I have a stackoverflow exception. Can someone please help ?

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        InitializeComponent();
        this.DataContext = this;
    }
    private string _lblValue;
    public string LabelValue
    {
        get
        {
            UpdateLabel();
            return _lblValue;
        }
        set
        {
            _lblValue = value;
            OnPropertyChanged(LabelValue);
        }
    }

    private void UpdateLabel()
    {
        _lblValue = System.DateTime.Now.ToString();
        //System.Threading.Thread.Sleep(2000);
        OnPropertyChanged("LabelValue");
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propName)
    {
        var handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propName));
        }
    }
}

推荐答案

正如 har07 所解释的那样，它是一个无限的 UI 循环.这是我对这个问题的修复.

As har07 explained it is a infinite UI loop. Here is my fix for this issue.

public partial class MainWindow : Window, INotifyPropertyChanged
{
    public MainWindow()
    {
        InitializeComponent();
        this.DataContext = this;

        Task.Run(() => UpdateLabel());
    }

    private string _lblValue;
    public string LabelValue
    {
        get
        {
            return _lblValue;
        }
        set
        {
            _lblValue = value;
            OnPropertyChanged();
        }
    }

    private void UpdateLabel()
    {
        while (true)
        {
            LabelValue = System.DateTime.Now.ToString();
            System.Threading.Thread.Sleep(1000);
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged([CallerMemberName] string propName = null)
    {
        var handler = PropertyChanged;
        if (handler != null)
        {
            handler(this, new PropertyChangedEventArgs(propName));
        }
    }
}

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