C# 重写IComparer 接口
首先定义比较类 继承自IComparer<Racer>
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1 public class RacerComparer : IComparer<Racer> 2 { 3 public enum CompareType 4 { 5 FirstName, LastName, Country, Wins 6 } 7 private CompareType compareType; 8 public RacerComparer(CompareType compareType) 9 { 10 this.compareType = compareType; 11 } 12 public int Compare(Racer x, Racer y) 13 { 14 if (x == null && y == null) return 0; 15 if (x == null) return -1; 16 if (y == null) return 1; 17 18 int result; 19 switch (compareType) 20 { 21 case CompareType.FirstName: 22 return string.Compare(x.FirstName, y.FirstName); 23 case CompareType.LastName: 24 return string.Compare(x.LastName, y.LastName); 25 case CompareType.Country: 26 result = string.Compare(x.Country, y.Country); 27 if (result == 0) 28 return string.Compare(x.LastName, y.LastName); 29 else 30 return result; 31 case CompareType.Wins: 32 return x.Wins.CompareTo(y.Wins); 33 default: 34 throw new ArgumentException("Invalid Compare Type"); 35 } 36 } 37 }
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1 class Racer : IComparable<Racer> 2 { 3 public int Id { get; private set; } 4 public string FirstName { get; set; } 5 public string LastName { get; set; } 6 public string Country { get; set; } 7 public int Wins { get; set; } 8 public override string ToString() 9 { 10 return String.Format("{0} {1}", FirstName, LastName); 11 } 12 public Racer(int id, string firstName, string lastName, string country) 13 : this(id, firstName, lastName, country, wins: 0) 14 { 15 } 16 public Racer(int id, string firstName, string lastName, string country, int wins) 17 { 18 this.Id = id; 19 this.FirstName = firstName; 20 this.LastName = lastName; 21 this.Country = country; 22 this.Wins = wins; 23 } 24 public int CompareTo(Racer other) 25 { 26 if (other == null) return -1; 27 int compare = string.Compare(this.LastName, other.LastName); 28 if (compare == 0) 29 return string.Compare(this.FirstName, other.FirstName); 30 return compare; 31 } 32 }
调用比较方法
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1 var graham = new Racer(7, "Graham", "Hill", "UK", 14); 2 var emerson = new Racer(13, "Emerson", "Fittipaldi", "Brazil", 14); 3 var mario = new Racer(16, "Mario", "Andretti", "USA", 12); 4 5 var racers = new List<Racer>(20) { graham, emerson, mario }; 6 racers.Sort(new RacerComparer(RacerComparer.CompareType.Country));
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