C#中委托用法

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。