public void CreateChallenge(string Name, List <string> Splits) { if (Name == null || Splits == null) { throw new ArgumentNullException(); } if (Splits.Count == 0) { throw new ArgumentException(); } Challenges.CreateChallenge(Name, Splits); challengeList = Challenges.GetChallenges(); CurrentChallenge = Name; // We changed some of our public properties. NotifyPropertyChanged("ChallengeList"); }