如何将SelectedItem(从ListBox)绑定到变量？

<ListBox ItemsSource="{Binding Items}" SelectedItem="{Binding SelectedItem}" />

private object _selectedItem;
public object SelectedItem
{
    get { return _selectedItem; }
    set
    {
        if (_selectedItem != value)
        {
            _selectedItem = value;
            OnPropertyChanged(nameof(SelectedItem));
        }
    }
}

private ObservableCollection<object> _items;
public ObservableCollection<object> Items
{
    get { return _items; }
    set
    {
        if (_items != value)
        {
            _items = value;
            OnPropertyChanged(nameof(Items));
        }
    }
}

public YourViewModel()
{
    Items = new ObservableCollection<object>();
    // 添加数据项到Items集合中
}

public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
    PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}