委托示例(利用委托对不同类型的对象数组排序)

using System;

using System.Collections.Generic;

using System.Text;



namespace delegateTest

{

    /// <summary>

    /// 演示利用委托给不同类型的对象排序

    /// </summary>

    class Program

    {

        delegate bool CompareOp(object lhs,object rhs);//声明委托(注意方法签名的格式是两个object类型参数)



        static void Main(string[] args)

        {

            Employee[] employees = {

                new Employee("Bugs Bunny",20000),

                new Employee("Elmer Fudd",10000),

                new Employee("Daffy Duck",25000),

                new Employee("Wiley Coyote",(decimal)1000000.38),

                new Employee("Foghorn Leghorn",23000),

                new Employee("Road Runner",50000)

            };



            CompareOp c1 = new CompareOp(Employee.CompareEmploySalary);



            BubbleSorter.Sort(employees, c1);//对employees数组，按工资高低排序



            for (int i = 0; i < employees.Length; i++)

            {

                Console.WriteLine(employees[i].ToString());

            }



            Console.WriteLine("---------------------------------------");



            object[] ints = { 3, 5, 2, 8, 6, 0 };



            c1 = new CompareOp(CompareInt);

            BubbleSorter.Sort(ints, c1);//对ints数组，按数值大小排序

            for (int i = 0; i < ints.Length; i++)

            {

                Console.WriteLine(ints[i].ToString());

            }



            Console.WriteLine("---------------------------------------");           



            Console.ReadLine();

        }



        /// <summary>

        /// 比较整数的大小

        /// </summary>

        /// <param name="x">整数1</param>

        /// <param name="y">整数2</param>

        /// <returns>如果第一个数小于第二数,返回true,反之false</returns>

        static bool CompareInt(object x, object y) 

        { 

            return (int)y>(int)x?true:false;

        }



        /// <summary>

        /// 冒泡排序类

        /// </summary>

        class BubbleSorter

        {

            static public void Sort(object[] sortArray, CompareOp gtMethod)

            {

                for (int i = 0; i < sortArray.Length; i++)

                {

                    for (int j = i + 1; j < sortArray.Length; j++)

                    {

                        if (gtMethod(sortArray[j], sortArray[i])) //比较大小，注:不同的object,比较大小的方法不同,比如Employee是按工资高低来比较,int是按数字大小来比较,利用委托的好处就在于不用管具体用哪种方法,具体调用的时候才确定用哪种方法

                        {

                            object temp = sortArray[i];

                            sortArray[i] = sortArray[j];

                            sortArray[j] = temp;

                        }

                    }



                }

            }

        }

    }



    

    /// <summary>

    /// 员工实体类

    /// </summary>

    class Employee 

    {

        private string name;

        private decimal salary;





        /// <summary>

        /// Employee构造函数

        /// </summary>

        /// <param name="name"></param>

        /// <param name="salary"></param>

        public Employee(string name, decimal salary) 

        {

            this.name = name;

            this.salary = salary;

        }



        /// <summary>

        /// 覆盖ToString()方法

        /// </summary>

        /// <returns></returns>

        public override string ToString()

        {

            return string.Format(name + ",{0:c}", salary);

        }



        /// <summary>

        /// 按员工工资高低比较大小

        /// </summary>

        /// <param name="lhs"></param>

        /// <param name="rhs"></param>

        /// <returns></returns>

        public static bool CompareEmploySalary(object lhs, object rhs) 

        {

            Employee empLhs = (Employee)lhs;

            Employee empRhs = (Employee)rhs;

            return (empRhs.salary > empLhs.salary) ? true : false;

        }

    }

}