转载

读改善c#代码157个建议：建议10~12

一、建议10：创建对象时需要考虑是否实现比较器

比较一下基本工资：

class Salary : IComparable {  public string Name { get; set; }  public decimal BaseSalary { get; set; } 
  public decimal Bonus { get; set; }     public int CompareTo(object obj)  {   Salary comparer = obj as Salary;      if (BaseSalary > comparer.BaseSalary)   {    return 1;   }   else if (BaseSalary == comparer.BaseSalary)   {    return 0;   }   else   {    return -1;   }  } }

客户端调用：

List<Salary> salaries = new List<Salary>();             salaries.Add(new Salary() { Name = "Sun", BaseSalary = 1000 });             salaries.Add(new Salary() { Name = "Yuan", BaseSalary = 2000 });             salaries.Add(new Salary() { Name = "Kun", BaseSalary = 3000 });             salaries.Add(new Salary() { Name = "Qun", BaseSalary = 3000 });             salaries.Add(new Salary() { Name = "Sun", BaseSalary = 4000 });              salaries.Sort();              foreach (var s in salaries)             {                 Console.WriteLine("【Name】：{0},【BaseSalary】：￥{1}{2}", s.Name, s.BaseSalary,System.Environment.NewLine);             }              Console.ReadKey();

运行：

读改善c#代码157个建议：建议10~12

如果不想用基本工资BaseSalary进行排序，而是以奖金Bonus进行排序，使用IComparer实现自定义比较器：

class BonusComparer : IComparer<Salary>     {         public int Compare(Salary x, Sarlary y)         {           return left.Bonus.CompareTo(right.Bonus);         }     }

客户端提供我们上面创建的比较器：

List<Salary> salaries = new List<Salary>();             salaries.Add(new Salary() { Name = "Sun", BaseSalary = 1000,Bonus=4000 });             salaries.Add(new Salary() { Name = "Yuan", BaseSalary = 2000, Bonus = 3000 });             salaries.Add(new Salary() { Name = "Kun", BaseSalary = 3000, Bonus = 2000 });             salaries.Add(new Salary() { Name = "Qun", BaseSalary = 3000,Bonus=4000 });             salaries.Add(new Salary() { Name = "Dun", BaseSalary = 4000,Bonus=0 });              salaries.Sort(new BonusComparer());              foreach (var s in salaries)             {                 Console.WriteLine("Name：【{0}】,BaseSalary：￥{1}，Bonus:{2}{3}", s.Name, s.BaseSalary,s.Bonus, System.Environment.NewLine);             }              Console.ReadKey();

输出：

读改善c#代码157个建议：建议10~12

二、建议11：区别对待==与Equals

两者都是指相等性，即：值相等性和引用相等性。

值类型：如果值类型相等，返回True。

引用类型：如果指向同一个引用，返回True。

很好理解，举个例子：

1、值类型：==与Equls()

            int x = 1;              int y = 1;              Console.WriteLine("int x=1;{0}int y=1;{0}", System.Environment.NewLine,System.Environment.NewLine);              Console.WriteLine("x==y:{0}",x == y);              Console.WriteLine("x.Equals(y):{0}{1}",x.Equals(y),System.Environment.NewLine);              x = y;              Console.WriteLine("x=y;{0}", System.Environment.NewLine);              Console.WriteLine("x==y:{0}", x == y);              Console.WriteLine("x.Equals(y):{0}", x.Equals(y));              Console.ReadKey();

运行：

读改善c#代码157个建议：建议10~12

2、引用类型

class People     {         public String Name { get; set; }     }

客户端：

People p1 = new People() { Name = "Sun" };              People p2 = new People() { Name = "Yuan" };              Console.WriteLine("People p1 = new People();{0}People p2 = new People();{1}", System.Environment.NewLine, System.Environment.NewLine);              Console.WriteLine("p1==p2:{0}", p1 == p2);              Console.WriteLine("p1.Equals(p2):{0}{1}", p1.Equals(p2), System.Environment.NewLine);              Console.WriteLine("------------------------------------");              p1 = p2;              p1.Name = "Moon";              Console.WriteLine("p1=p2;{0}", System.Environment.NewLine);              Console.WriteLine("p1==p2:{0}", p1 == p2);              Console.WriteLine("p1.Equals(p2):{0}", p1.Equals(p2));

运行：

读改善c#代码157个建议：建议10~12

后面我们修改了p1里Name="Moon"的值，但是，p2的Name值也变成了Moon。所以，==与Equal()在比较引用类型时，引用地址一样，返回True

3、引用类型重载Equals()达到值类型比较效果

还有一点，有时我们需要我们的类型看上去和string类型类似，有值类型的感觉。所以说，我们的这个引用类型，需要重载==或者Equals()。

这里建议只重载Equals()来达到像值类型一样的比较效果。保留==，保留引用比较。例如：生活中我们认为身份证号码一样的是同一个人。

class People {  public String Name { get; set; }  public string IDCode { get; set; }  public override bool Equals(object obj)  {   People p = obj as People;   return p.IDCode == IDCode;  } }

客户端：

People p1 = new People() { IDCode="No1" };              People p2 = new People() { IDCode = "No1" };              Console.WriteLine("People p1 = new People();{0}People p2 = new People();{1}", System.Environment.NewLine, System.Environment.NewLine);              Console.WriteLine("p1.IDCode={0}", p1.IDCode);             Console.WriteLine("p2.IDCode={0}", p2.IDCode);             Console.WriteLine();              Console.WriteLine("p1==p2:{0}【保留引用地址的对比】", p1 == p2);              Console.WriteLine("p1.Equals(p2):{0}【重载比较IDCode,值类型比较效果】{1}", p1.Equals(p2), System.Environment.NewLine);              Console.WriteLine("----------------------------------");              p1 = p2;              p1.IDCode = "No2";              Console.ForegroundColor = ConsoleColor.Red;              Console.WriteLine("p1.IDCode={0}", p1.IDCode);             Console.WriteLine("p2.IDCode={0}", p2.IDCode);             Console.WriteLine();              Console.ForegroundColor = ConsoleColor.White;              Console.WriteLine("p1=p2;{0}", System.Environment.NewLine);              Console.WriteLine("p1==p2:{0}", p1 == p2);              Console.WriteLine("p1.Equals(p2):{0}", p1.Equals(p2));              Console.ReadKey();