C#集合与列表(一) -- 对象的统一性和对象的等值性

　　首先创建一个Person类.

 public class Person
        {
                string FirstName;
                string LastName;

                public Person(string first, string last)
                {
                        FirstName = first;
                        LastName = last;
                }

                public string FullName
                {
                        get { return FirstName + " " + LastName; }
                }

}

class Program
        {
                static void wl(string s)
                {
                        Console.WriteLine(s);
                }
                static void w(string s)
                {
                        Console.Write(s);
                }
                static void br()
                {
                        Console.WriteLine();
                }
                static void Main(string[] args)
                {                       
                        #region ArrayDemo
                        Person scott = new Person("Scott", "Hanselman");
                        Person bill = new Person("Bill", "Evjen");
                        Person srini = new Person("Srinivasa", "Sivakumar");

                        Person[] people ={ bill, scott, srini };

                        Console.WriteLine("We used foreach.");
                        foreach (Person p in people)
                        {
                                Console.WriteLine(p.FullName);
                        }
                        br();
                        Console.WriteLine("We used a for loop.");
                        {
                                for (int i = 0; i < people.Length; i++)
                                {
                                        Console.WriteLine(people[i].FullName);
                                }
                        }
                        br();

                        Person scott2 = new Person("Scott", "Hanselman");
                        int indexOfBill = Array.IndexOf(people, bill);
                        wl("Bill is at " + indexOfBill);
                        int indexOfScott = Array.IndexOf(people, scott);
                        wl("Scott is at " + indexOfScott);
                        int indexOfScott2 = Array.IndexOf(people, scott2);
                        wl("Scott2 is at " + indexOfScott2);

                        #endregion

                        Console.ReadKey();
                }
        }

执行结果如下:

 

虽然这两个对象包含相同的至,但不是同一对象, 如果要获取scott对象的索引,同时把scott2作为要搜索的对象,只需在Person类上提供一个Equals方法, 系统更可以使用该方法建立值相等的对象；

在Person类中重写Equals方法之后的结果如下: 

 public override bool Equals(object obj)
                {
                        Person other = obj as Person;
                        return (other.LastName == this.LastName && other.FirstName == this.FirstName);
                }

 

执行结果:

 

 

object.Equals方法与 object.ReferenceEquals说明:

object.Equals: 用于对象的等值性比较

object.ReferenceEquals: 用于对象的同一性比较 

Person scott = new Person("Scott", "Hanselman");
                        Person bill = new Person("Bill", "Evjen");
                        Person srini = new Person("Srinivasa", "Sivakumar");

                        Person scott2 = new Person("Scott", "Hanselman");
                        int indexOfBill = Array.IndexOf(people, bill);
                        wl("Bill is at " + indexOfBill);
                        int indexOfScott = Array.IndexOf(people, scott);
                        wl("Scott is at " + indexOfScott);
                        int indexOfScott2 = Array.IndexOf(people, scott2);
                        wl("Scott2 is at " + indexOfScott2);
                        Person scott3 = scott2;

                        br();
                        wl("Equals " + object.Equals(scott, scott2).ToString());//对象等值性比较
                        wl("ReferenceEquals " + object.ReferenceEquals(scott, scott2));//对象同一性比较
                        #endregion