委托使用（1）
这是一个委托排序的例子
public enum Comparsion
{
theFirstComesFirst=1,
theSecondComesFirst=2
} //来决定排序的顺序
class Pair<T> //在下面我创建的两个类Student，Dog，都把他们保存在Pair里面
{
private T[] thePair = new T[2];
public delegate Comparsion WhichIsFirst(T obj1,T obj2); //定义委托
public Pair(T firstObject,T secondObject)
{
thePair[0] = firstObject;
thePair[1] = secondObject;
}
/// <summary>
/// 排序的过程
/// </summary>
/// <param name="whileIsFirst">一个委托实例的传入</param>
public void Sort(WhichIsFirst whileIsFirst)
{
if (whileIsFirst(thePair[0], thePair[1]) == Comparsion.theSecondComesFirst)
{
T same;
same = thePair[0];
thePair[0] = thePair[1];
thePair[1] = same;
}
}
public override string ToString() //重载ToString（）方法
{
return thePair[0].ToString()+thePair[1].ToString(); //调用Studnt或Dog中的ToString（）方法
}
}
定义Student类
class Student {
public static readonly Pair<Student>.WhichIsFirst w = new Pair<Student>.WhichIsFirst(Student.StudentWhileIsFirst);//如果不想再客户端中申明委托实例，可是在类中写一个静态只读的委托实例
private String _name;
public Student(String name)
{
this._name = name;
}
public static Comparsion StudentWhileIsFirst(Student s1,Student s2)//这里我用的是静态方法，定义一个委托的方法，要跟定义委托的格式一样
{
return String.Compare(s1._name, s2._name) < 0 ? Comparsion.theFirstComesFirst : Comparsion.theSecondComesFirst;
}
public override string ToString()
{
return _name;
}
}
定义Dog类
class Dog
{
private String _weight;
public Dog(String weight)
{
this._weight = weight;
}
public Comparsion DogWhileIsFirst(Dog d1, Dog d2) //这里我用的是类的实例方法
{
return String.Compare(d1._weight, d2._weight) < 0 ? Comparsion.theFirstComesFirst : Comparsion.theSecondComesFirst;
}
public override string ToString()
{
return _weight;
}
}
客户端代码
Student s1=new Student("gu");
Student s2=new Student("bao");
Pair<Student> pairStudent = new Pair<Student>(s1, s2);
//Pair<Student>.WhichIsFirst stuWhile=new Pair<Student>.WhichIsFirst(Student.StudentWhileIsFirst); //如果Student中没有那个静态只读的成员，就用这一句在然后再调用 pairStudent.Sort(stuWhile)
pairStudent.Sort(Student.w);
Console.WriteLine("pairStudent:{0}",pairStudent.ToString());
Dog d1 = new Dog("56");
Dog d2 = new Dog("54");
Pair<Dog> pairDog = new Pair<Dog>(d1,d2);
Pair<Dog>.WhichIsFirst dogWhile = new Pair<Dog>.WhichIsFirst(d1.DogWhileIsFirst);
pairDog.Sort(dogWhile);
Console.WriteLine("dogStudent:{0}", pairDog.ToString());
