在静态方法中使用非静态值？

Question

I am currently using the sample app from https://github.com/xabre/xamarin-bluetooth-le , which shows data from a sensor in real-time. My goal now is to display a chart with this data, so I am using the Microcharts package. When using the following code with static data (and declaring the List as static) the chart works fine, but, when I try to use the real-time data (CharacteristicValue) I get the errors:

Error CS0120 An object reference is required for the non-static field, method, or property 'CharacteristicDetailViewModel.entries'
Error CS0236 A field initializer cannot reference the non-static field, method, or property 'CharacteristicDetailViewModel.CharacteristicValueTemp'

I understand that this is happening because the data is changing, but I wonder if there is any workaround I could use to display the data in real-time?

In my ViewModel I have:

 public List<ChartEntry> entries = new List<ChartEntry>
     {
         new ChartEntry(CharacteristicValue)
         {
             Color=SKColor.Parse("#FF1943"),
             Label ="January",
             ValueLabel = "200"
         },
         new ChartEntry(400)
         {
             Color = SKColor.Parse("00BFFF"),
             Label = "March",
             ValueLabel = "400"
         },

     };

And in the .xaml.cs file:

 public CharacteristicDetailPage()
    {
        
        InitializeComponent();

        ChartTest.Chart = new LineChart() 
            {
                Entries = CharacteristicDetailViewModel.entries,
                LineMode = LineMode.Straight,
                LineSize = 8,
                PointMode = PointMode.Square,
                PointSize = 18,
            };
    }

(Yes, I know this chart makes no sense right now, I just wannna make the updating work before it gets more complicated)

Thank you! :)

Answer 1

CharacteristicDetailViewModel.entries is not a static member. You need a concrete instance of a CharacteristicDetailViewModel :

var myCharacteristicDetailVM = /*some initializing or retrieval logic of a concrete instance of the VM*/

And then:

ChartTest.Chart = new LineChart() 
{
    Entries = myCharacteristicDetail.entries /*a concrete instance of the VM*/, 
    LineMode = LineMode.Straight,
    LineSize = 8,
    PointMode = PointMode.Square,
    PointSize = 18,
};

That said, you seem to have a deep misunderstanding about what static actually means in c#. I suggest you read up on the subject here .