Xamarin ZXing Qr to List

Question

In my project i need contunistly read barcode and put them in a list. But while i trying it its always giving me NullReferenceException but i didn't get it. When i check it in debug i can see it have a string value but while trying put it to list its always giving me that error. Its my code for Scan and take data:

 List<HoldMyString> mylist;  
 HoldMyString hold;
    private void ZXingScannerView_OnScanResult(ZXing.Result result)
    {
        Device.BeginInvokeOnMainThread(() =>
        {
            hold.HoldString = result.Text;  // HoldString is taking string value

            mylist.Add(hold);    
           

            
        });
    }

How i can put my datas in to my list contunistly. Thanks for help!

Answer 1

I was able to reproduce the same error with yours.

You could use the code below.

HoldMyString:

 public class HoldMyString
{
    public string HoldString { get; set; }
}

Code for Scan and take data:

  List<HoldMyString> mylist=new List<HoldMyString>();
    HoldMyString hold = new HoldMyString();
    private void Handle_OnScanResult(ZXing.Result result)
    {
        Device.BeginInvokeOnMainThread(() =>
        {
            hold.HoldString = result.Text;  // HoldString is taking string value

            mylist.Add(hold);
        });
    }

For more details about how to get the barcodes, you could check the thread i done before. How to embed ZXing scanner in PageRenderer/Fragment/View into Xamarin.Forms ContentPage?