WPF コントロールにバインドしたデータを更新する

public class Class1 : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler? PropertyChanged;

    private void RaisePropertyChanged([CallerMemberName] String propertyName = "")
    {
        // propertyName 呼び出し元のプロパティ名

        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }

    private DateTime dateTime1 = DateTime.Now;

    public DateTime DateTime1
    {
        get { return dateTime1; }
        set
        {
            if (dateTime1 != value)
            {
                dateTime1 = value;
                RaisePropertyChanged();
            }
        }
    }

    // 比較用
    public DateTime DateTime2 { get; set; } = DateTime.Now;
}
 

<Grid>
    <StackPanel>
        <TextBlock Text="{Binding DateTime1}"/>
        <TextBlock Text="{Binding DateTime2}"/>
        <Button Content="button" Click="Button_Click"/>
    </StackPanel>
</Grid>
 

public partial class MainWindow : Window
{
    Class1 class1=new Class1();

    public MainWindow()
    {
        InitializeComponent();

        this.DataContext = class1;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        class1.DateTime1 = DateTime.Now;
        class1.DateTime2 = DateTime.Now;
    }
}