使用数据绑定在文本框中显示文本文件数据

Question

I am trying to read the text file in textbox with the help of data binding.

Here is the code of class where i used get and set properties

public class FileData : INotifyPropertyChanged
{
    public string data;
    public string Data
    {
        get { return data; }
        set
        {
            data = value;
            OnPropertyChanged();
        }
    }

    public FileData(string data)
    {
        Data = data;
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged([CallerMemberName] string caller = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(caller));
        }
    }
}

}

And this is the code of Mainpage.Xaml.cs

     private async void Button_Click_1(object sender, RoutedEventArgs e)
    {

        display.DataContext = fd;
        StorageFile file = await      ApplicationData.Current.LocalFolder.GetFileAsync(filenamebox.Text + ".txt");
        fd.Data = await FileIO.ReadTextAsync(file);
    }

And when i read the file this exception comes out

"Object reference not set to an instance of an object."

please help me :(

Answer 1

Check if file return is null or not

StorageFile file = await ApplicationData.Current.LocalFolder.GetFileAsync(filenamebox.Text + ".txt");
if ( file != null)
{
     // Do what you want
}