C# null reference error

Question

Can't seem to find what's wrong here, I'm using this method :

public void AddPlayerToTeam(Player player, Team team)
{
    Team t = new Team();
    if(team.PlayersList.Count>=20)
        return;
    if (!(team.PlayersList.Contains(player)))
        team.PlayersList.Add(player); 
}

and later in this test:

[TestMethod]
public void CheckTeamOfPlayer9()
{
    Assert.AreEqual(wcm.GetPlayerById(9).PlayerTeam.CountryName, "Japan");
}

I get the following error: Object reference not set to an instance of an object. with the null reference exception. This is the method the test runs:

public Player GetPlayerById(int playerId)
{
    var result = from b in Players
                 where b.PersonId.Equals(playerId)
                 select b;

    return result.FirstOrDefault(); 
}

Any one has an idea?

Your debugger will tell you where the problem is. Some referenced object is null. — Bart Friederichs, Nov 12 '13 at 18:25
Where are you creating a player with ID 9? `GetPlayerById` will return null if there's no such player... — Jon Skeet, Nov 12 '13 at 18:25
`wcm.GetPlayerById(9).PlayerTeam` is the culprit. Either wcm, GetPlayerById(9) or PlayerTeam is returning null. — crthompson, Nov 12 '13 at 18:26
And what would you like us to do? Do you want us to guess which of the references contains a null reference? It's impossible for us to see and very easy for you to check, since you are running your program and having presumably using a debugger. — Steven, Nov 12 '13 at 18:30

score 1 · Accepted Answer · answered Nov 12 '13 at 18:34

1

return result.FirstOrDefault() will return a default value if thaere is no match. In the case of Player, that is null.

Check the result of wcm.GetPlayerById(9). Presumably it is null.

answered Nov 12 '13 at 18:34

David Arno

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C# null reference error

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