I can't seem to test for a null in this c# Unity script-CodePudding

I have a Unity App that is using c#.

I am getting a NullReferenceException: Object reference not set to an instance of an object on the line:

WeatherDict.Add(WeatherTypes[i].WeatherId, new List<WeatherMaps>());

for WeatherTypes[i].WeatherId

I am trying to check for null by using string.IsNullOrWhiteSpace as you can see.

for (int i = 0; i < WeatherTypes.Length; i  )
{
    if (!string.IsNullOrWhiteSpace(WeatherTypes[i].WeatherId))
    {
        if (!WeatherDict.ContainsKey(WeatherTypes[i].WeatherId))
        {
            WeatherDict.Add(WeatherTypes[i].WeatherId, new List<WeatherMaps>());
        }
    }
}

I also tried this:

if (WeatherTypes[i].WeatherId != null || WeatherTypes[i].WeatherId != "")

But that still throws the same exception.

Is there another way to check for null?

Thanks!

CodePudding user response：

If Weathertypes is null, the following code will cause a null reference exception:

if (WeatherTypes[i].WeatherId != null || WeatherTypes[i].WeatherId != "")

A safer approach looks like this.

if (WeatherTypes == null || WeatherTypes[i] == null)

You should learn to use the debugger. It will allow you to step through the code and look and see exactly what is null.