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

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)); } }}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; } }}
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"); Student s2 = new Student(2, "ls", Genders.female, DateTime.Parse("1986-12-03"), "13188522888"); Student s3 = new Student(3, "ww", Genders.female, DateTime.Parse("1988-11-15"), "13288576885"); Student s4 = new Student(4, "zl", Genders.male, DateTime.Parse("1984-02-21"), "13388534635"); Student s5 = new Student(5, "qq", Genders.female, DateTime.Parse("1988-02-23"), "13488524335"); Student s6 = new Student(6, "cb", Genders.male, DateTime.Parse("1989-02-23"), "13588527636"); c1.AllStudents.Add(s1); c1.AllStudents.Add(s2); c1.AllStudents.Add(s3); c1.AllStudents.Add(s4); c1.AllStudents.Add(s5); c1.AllStudents.Add(s6); ArrayList list= c1.FindAll(match); //查找班级女生的资料 // ArrayList list = c1.FindAll(match1); //查找学号从1到5的学生 foreach (Student s in list) { s.show(); } } //条件为女性 public static bool match(Student s) { if (s.Gender.Equals(Genders.female)) { return true; } return false; } //条件为学号从1到5 public static bool match1(Student s) { if (s.Id.CompareTo(1) >= 0 && s.Id.CompareTo(5) <= 0) { return true; } return false; } }}

希望本文所述对大家的C#程序设计有所帮助。