ICompareable和IComparer结合 比较大小

 

将ICompareable和IComparer结合 比较大小

这儿注意的是PersonComparer的比较方法 CompareTo调用了Person对象的重载比较方法CompareTO

        public int CompareTo(object obj, PersonCompareType compareType)
{.....
}

这样的话，Person能根据Comparer传过来的参数，进行相应的排序比较

using System;
using System.Collections;//注意using Collections
using System.Collections.Generic;
using System.Text;

namespace ZyyLove2008
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList list = new ArrayList();
            Random random = new Random();

            list.Add(new Person("A", 4));
            list.Add(new Person("B", 3));
            list.Add(new Person("D", 5));
            list.Add(new Person("C", 2));     
      
            foreach (Person personTmp in list)
            {
                Console.WriteLine(personTmp.Name + "\t" + personTmp.Age.ToString());
            }

            list.Sort(new PersonComparer(PersonCompareType.Name));
            Console.WriteLine("\r\nAfter sorting by Name\r\n");
            foreach (Person personTmp in list)
            {
                Console.WriteLine(personTmp.Name + "\t" + personTmp.Age.ToString());
            }

            list.Sort(new PersonComparer(PersonCompareType.Age));
            Console.WriteLine("\r\nAfter sorting by Age\r\n");
            foreach (Person personTmp in list)
            {
                Console.WriteLine(personTmp.Name + "\t" + personTmp.Age.ToString());
            }
            Console.Read();
        }
    }

    public class Person : IComparable
    {
        private string _name;
        public string Name
        {
            get
            {
                return _name;
            }
            set
            {
                _name = value;
            }
        }
        private int _age;
        public int Age
        {
            get
            {
                return _age;
            }
            set
            {
                _age = value;
            }
        }

        public Person(string name, int age)
        {
            this._name = name;
            this._age = age;
        }

        #region IComparable Members

        public int CompareTo(object obj)
        {
            Person personTmp = obj as Person;
            if (personTmp == null)
            {
                throw new ArgumentException("obj value is not a type of Person", "obj");
            }
            return string.Compare(this.Name, personTmp.Name);
        }

        /// <summary>
        /// Person's Overloaded CompareTo Method
        /// </summary>
        /// <param name="obj"></param>
        /// <param name="compareType"></param>
        /// <returns></returns>
        public int CompareTo(object obj, PersonCompareType compareType)
        {
            int result = 0;
            Person personTmp = obj as Person;
            if (personTmp == null)
            {
                throw new ArgumentException("obj value is not a type of Person", "obj");
            }
            switch (compareType)
            {
                case PersonCompareType.Default:
                case PersonCompareType.Name:
                    result= string.Compare(this.Name, personTmp.Name);
                    break;
                case PersonCompareType.Age:
                   result= this.Age.CompareTo(personTmp.Age);
                   break;
                default:
                    System.Diagnostics.Debug.Assert(false);
                    break;
            }
            return result;
        }

        #endregion
    }


    public class PersonComparer : IComparer
    {
        private PersonCompareType _compareType;
        public PersonCompareType CompareType
        {
            get
            {
                return _compareType;
            }
            set
            {
                _compareType = value;
            }
        }

        public PersonComparer(PersonCompareType compareType)
        {
            _compareType = compareType;
        }

        #region IComparer Members
        /// <summary>
        /// Compares two objects and returns a value indicating whether one is less than,
        /// equal to, or greater than the other.
        /// </summary>
        /// <param name="x">The first object to compare.</param>
        /// <param name="y">The second object to compare.</param>
        /// <returns></returns>
        public int Compare(object x, object y)
        {
            Person personX = x as Person;
            if (personX == null)
            {
                throw new ArgumentException("x value is not a type of Person", "x");
            }
            Person personY = y as Person;
            if (personY == null)
            {
                throw new ArgumentException("y value is not a type of Person", "y");
            }
            return personX.CompareTo(personY, _compareType);
        }

        #endregion
    }

    public enum PersonCompareType
    {
        Default,
        Name,
        Age
    }
}

Execute result as follow..