本文实例讲述了C#中委托用法。分享给大家供大家参考。具体分析如下：

　　对于用户要查找的条件的千变万化,我们在写条件去查找时,是不可能一下写死的,那样,如果你写好了一个类让别人用,别人需要的不是那种查询,得去找你改条件.

　　那么我们能否让使用这个类的人自己定义一个规则(条件),直接传条件给你,你帮我查询出结果来,C#就可以用委托来解决,相应的java可以用接口来实现

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 using System; using System.Collections.Generic; using System.Text; using System.Collections; namespace FinderTest { //性别枚举 public enum Genders { male=1,female=2 } //学生类 public class Student { public Student() { } public Student(int _id, string _name, Genders _gender, DateTime _birthday, string _telephone) { this._id = _id;//学生id this._name = _name;//学生姓名 this._gender = _gender;//学生性别 this._birthday = _birthday;//学生生日 this._telephone = _telephone;//学生电话 } int _id; public int Id { get { return _id; } set { _id = value; } } string _name; public string Name { get { return _name; } set { _name = value; } } Genders _gender; public Genders Gender { get { return _gender; } set { _gender = value; } } DateTime _birthday; public DateTime Birthday { get { return _birthday; } set { _birthday = value; } } private string _telephone; public string Telephone { get { return _telephone; } set { _telephone = value; } } public void show() { Console.WriteLine(string.Format("我的姓名:{0}/t学号:{1}/t性别:{2}",_name,_id,_gender)); } } }

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 using System; using System.Collections.Generic; using System.Text; using System.Collections; namespace FinderTest { //学期枚举 public enum Semesters { x1 = 1, x2 = 2, x3 = 3 } public delegate bool Predicate(Student s);//定义一个委托 //班级类 public class Class : ArrayList { public Class() { } public Class(string _name, string _master, Semesters _semester) { this._name = _name; this._master = _master; this._semester = _semester; _allStudents = new ArrayList(); } private string _name;//班级名字 public string Name { get { return _name; } set { _name = value; } } private string _master;//班长 public string Master { get { return _master; } set { _master = value; } } private Semesters _semester;//学期 public Semesters Semester { get { return _semester; } set { _semester = value; } } //班级里的学生集合 ArrayList _allStudents; public ArrayList AllStudents { get { return _allStudents; } } public ArrayList FindAll(Predicate match) { if (match == null) { return this._allStudents; } ArrayList result = new ArrayList(); for (int i = 0; i < this._allStudents.Count; i++) { Student one = (Student)this._allStudents[i]; if (match(one)) { result.Add(one); } } return result; } } }

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 using System; using System.Collections.Generic; using System.Text; using System.Collections; namespace FinderTest { class Program { static void Main(string[] args) { Class c1 = new Class("0603", "jsp", Semesters.x1); Student s1 = new Student(1, "zs", Genders.male, DateTime.Parse("1988-02-23"), "13088522635");