Show Balance after user is selected-CodePudding

            var user = (User)cbUser.SelectedItem;
            tbBalance.Text = "Balans: "   user.Balance.ToString();

So I want to use this code to print the balance of each user for a gambeling app. Only the problem is that this gives me an error before the app starts saying user is null. Is there a way to run this code after the user is selected. My user can be selected in a combobox in a xaml application binded to my User class.

I tried to use a AfterSelected method but this gave me weird errors and I really don't how to use such a method.

CodePudding user response：

You can also reset the text when there's nothing selected.

var user = (cbUser as User)?.SelectedItem;
tbBalance.Text = $"Balans: {user?.Balance ?? "N/A"}";

This means that if nothing is selected, the balance text would be "Balans: N/A".

This code will also ensure that no nasty "object reference not set to an instance of an object" errors are thrown.

CodePudding user response：

Use defensive coding, one way is below.

var user = (User)cbUser?.SelectedItem;
if(user != null)
{
    tbBalance.Text = "Balans: "   user.Balance.ToString();
}

That means whether the user is null then this code will not execute, otherwise it will execute.