Carpool Project: Part #11
October 13, 2010 Leave a comment
I wanted to have a list of all of the swimmers NOT associated with a carpool. I got a list of all swimmers and then a list of all swimmers in carpool. I first started doing some nested For..Each and quickly realized I was doing something wrong. I went to 101 LINQ Samples and got a much better implementation (sample #52). I whipped this code:
1 public static List<Swimmer> GetNonCarpooledSwimmers(int carpoolId) 2 { 3 List<Swimmer> allSwimmers = SwimmerFactory.GetAllSwimmers(); 4 List<Swimmer> carpooledSwimmers = CarpoolFactory.GetCarpool(carpoolId).Swimmers; 5 return allSwimmers.Except(carpooledSwimmers).ToList<Swimmer>(); 6 } 7
and ran a test:
Red! Dangnabbit.
I went to the definition of Except and realized that I did not implement a custom GetHashCode or Equals() for Swimmer. I popped this code into my Swimmer class:
1 2 public override int GetHashCode() 3 { 4 return this.Id; 5 } 6 7 public override bool Equals(object obj) 8 { 9 Swimmer other = obj as Swimmer; 10 if (other == null) 11 { 12 return base.Equals(obj); 13 } 14 else 15 { 16 if (other.Id == this.Id) 17 { 18 return true; 19 } 20 else 21 { 22 return false; 23 } 24 25 } 26 } 27
And things ran like a champ…
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