调用的ObservableCollection代码get访问再次落后

Question

是否有可能再次调用ObservableCollection get方法？我需要改变基于ItemsSource选择ComboBox所以我需要调用我的ObservableCollection再次，这是我的代码

ObservableCollection<string> sampleData = new ObservableCollection<string>();
public ObservableCollection<string> SampleData
{
    get
    {
        if (sampleData.Count < 1)
            sampleData.Add(line);  

        return sampleData;
    }
}

上面的代码运行一次，当应用程序luanch，但我需要的时候调用它改变组合框

private void CmbFilter_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    switch (cmbFilter.SelectedIndex)
    {
        case 0:         
            break;
        case 1:
            break;
        case 2:
            break;
        case 3:
            break;
    }
}

Answer 1

一个ObservableCollection整点是，你并不需要实现你在你的SampleData吸气剂暗示什么。还有你可以采取这里2点的方法：

利用ObservableCollection的

注意，有更好的选择，在这里，但出了问题的范围。查找了SelectedItem绑定一个ComboBox。

private void CmbFilter_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    // Modify your collection here based on what was selected.
}

忘掉ObservableCollection

这种方法要求你实现INotifyPropertyChanged您ViewModel类。

public IEnumerabe<string> SampleData
{
    get
    {
        // Return values based on the selection.
        if (SelectedData == "FirstValueICareAbout") // SelectedData assumes you have investigated how to bind to the SelectedItem of a ComboBox.
        {
            return new[]
            {
                "FirstValue",
                "SecondValue"
            };    
        }

        return Enumerable.Empty<string>();
    }
}

private void CmbFilter_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
    // Notify the UI that SampleData has changed using INotifyPropertyChanged implementation.
    RaiseNotifyPropertyChanged(nameof(SampleData));
}