List<T> 排序(Sort)查找(Find)功能的多种实现

记录 List<T>功能中的Sort和Find功能的几种实现方式

 

Person类

    public class Person:IComparable<Person>

    {

        public string Name { get; set; }

        public int Age { get; set; }

        public Person(string name, int age)

        {

            this.Name = name;

            this.Age = age;

        }



        public int CompareTo(Person p)

        {

            return this.Age - p.Age;

        }



        public static int NameCompareTo(Person p1, Person p2)

        {

            return System.Collections.Comparer.Default.Compare(p1.Name, p2.Name);

        }  

    }

 

 调用类

 

List<Person> Persons = new List<Person>() { 

                new Person("jdmin",20),

                new Person("aleax",35),

                new Person("xhina",23)

            };

            //排序

            //方法 1. 让Person类继承IComparable接口,实现CompareTo方法

            //Persons.Sort();

            //方法2.自定义一个方法来实现

            Persons.Sort(Person.NameCompareTo);

            //Persons.Sort(delegate(Person p1, Person p2) { return Comparer.Default.Compare(p2.Name, p1.Name); });

            foreach (Person p in Persons)

            {

                Console.WriteLine(p.Name + " Age:" + p.Age);

            }

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

            //方法3. 使用Lambada

            //"Lambda表达式" 的语法格式：

            //参数列 => 语句或语句块

            //如果参数列中有0个或1个以上参数，则必须使用括号括住参数列

            var temList = Persons.OrderBy(p => p.Name);//名字升序, A-Z

            //var temList = Persons.OrderByDescending(p => p.Age);//按年龄降序

            foreach (Person p in temList)

            {

                Console.WriteLine(p.Name + " Age:" + p.Age);

            }

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



            //查找年龄>25的数据

            //查找单个数据

            Person oPerson = Persons.Find(delegate(Person p) { return p.Name == "aleax"; });

            Console.WriteLine("Name: {0}, Age: {1}", oPerson.Name, oPerson.Age);

            //查找出满足条件的所有数据

            List<Person> ageList = Persons.FindAll(AgeFind);

            //var ageList = Persons.FindAll(delegate(Person p) { return p.Age > 25; });

            //var ageList = Persons.Where(p => p.Age > 25);

            foreach (Person p in ageList)

            {

                Console.WriteLine(p.Name + " Age:" + p.Age);

            }

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

            //查看指定的名字是否存在

            var bUserExists=Persons.Exists(delegate(Person p){return p.Name=="aleax";});

            Console.WriteLine(bUserExists);

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