I have recently learned Asp.Net and used C# to write code. When learning C#, I found that many beginners do not have a special understanding of inheritance and polymorphism, so I made this example. I hope it will be helpful to you. The example is very simple.
Page FileTestProfileClass2.aspx
<%@ Page Language="C#" ContentType="text/html" ResponseEncoding="gb2312" Src="profile2.cs" %>
<%@ Import Namespace="shai" %>
<html>
<head>
<style>
div{font:Arial, Helvetica, sans-serif;
background-color:#cccccc;
border-color:black;
border-width:1;
border-style:solid;
padding:10,10,10,10;
}
</style>
<script language="c#" runat="server">
public void Page_Load(Object sender,EventArgs e)
{
Profile profile = new Profile();
message.InnerHtml += "<u>Profile Class</u><br>";
message.InnerHtml += "Firstname:"+profile.getFirstname()+"<br>";
message.InnerHtml += "Lastname:"+profile.getLastname()+"<br>";
message.InnerHtml += "Phone:"+profile.getPhonenumber()+"<br><br>";
profile.save();
ExtendedProfile extendedprofile = new ExtendedProfile();
message.InnerHtml += "<u>ExtendedProfile Class</u></br>";
message.InnerHtml += "Firstname:"+profile.getFirstname()+"<br>";
message.InnerHtml += "Lastname:"+profile.getLastname()+"<br>";
message.InnerHtml += "Phone:"+extendedprofile.getPhonenumber()+"<br>";
message.InnerHtml += "Address1:"+extendedprofile.getAddress1()+"<br>";
message.InnerHtml += "Address2:"+extendedprofile.getAddress2()+"<br>";
message.InnerHtml += "City:"+extendedprofile.getCity()+"<br>";
message.InnerHtml += "State:"+extendedprofile.getState()+"<br>";
message.InnerHtml += "Postal:"+extendedprofile.getPostal()+"<br>";
message.InnerHtml += "Description:"+extendedprofile.getDescription()+"<br>";
extendedprofile.save();
}
</script>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title></title>
</head>
<body style="font:Arial, Helvetica, sans-serif">
<b><h3>Simple inheritance/polymorphism example</h3></b><br><br>
object output:<br>
<br>
<div id="message" runat="server" />
</body>
</html>
Class definition file profile2.cs
using System;
using System.IO;
using System.Xml;
namespace shai //namespace shai
{
interface ISaveData //Define an interface ISaveData, which is inherited as the base class of Profile. Due to its polymorphic characteristics, it can be
{ //Different classes call methods and modify them
void save();
}
public class Profile:ISaveData //Define class Profile
{
protected string _firstname; //It contains three attributes, namely _firstname, _lastname, phonenumber
protected string _lastname;
protected string _phonenumber;
public Profile() //Define the initial value for the property
{
_firstname = "Saidy";
_lastname = "Chen";
_phonenumber = "(010)88716990";
}
public string getPhonenumber() //Method getPhonenumber() in Profile class
{
return _phonenumber;
}
public virtual void setPhonenumber(string phonenumber)
{
_phonenumber = phonenumber;
}
public string getFirstname() //Method getFirstname() in Profile class
{
return _firstname;
}
public void setFirstname(string firstname)
{
_firstname = firstname;
}
public string getLastname() //Method getLastname() in Profile class
{
return _lastname;
}
public void setLastname(string lastname)
{
_lastname = lastname;
}
public virtual void save() //Call the save() method of the ISaveData interface
{
//Save data in Text format
FileStream fs = new FileStream("D:\myweb2\profile2.txt",FileMode.Create,FileAccess.Write);
StreamWriter sw = new StreamWriter(fs);
sw.WriteLine("Firstname:"+_firstname.ToString());
sw.WriteLine("Lastname:"+_lastname.ToString());
sw.WriteLine("Phone:"+_phonenumber.ToString());
sw.Flush();
sw.Close();
fs.Close();
}
}
public class ExtendedProfile:Profile creates a Profile subclass ExtendedProfile, which can inherit the methods in Profile
{
protected string _address1; //Attributes of the subclass ExtendedProfile
protected string _address2;
protected string _city;
protected string _state;
protected string _postal;
protected string _description;
public ExtendedProfile() //Initial value of attributes in subclass ExtendedProfile
{
_address1 = "Tsinghua University";
_address2 = "Tsinghua University Physics Laboratory";
_city = "Beijing";
_state = "Beijing";
_postal = "100024";
_description = "Professor";
}
public override void setPhonenumber(string phonenumber) //Inherit the setPhonenumber() method in class Profile
{ //Overloading of setPhonenumber() method
_phonenumber = phonenumber;
}
public string getAddress1() //The method getAddress1() in the subclass ExtendedProfile, and so on
{
return _address1;
}
public string getAddress2()
{
return _address2;
}
public void setAddress(string address1,string address2)
{
_address1 = address1;
_address2 = address2;
}
public string getCity()
{
return _city;
}
public void setCity(string city)
{
_city = city;
}
public string getState()
{
return _state;
}
public void setState(string state)
{
_state = state;
}
public string getPostal()
{
return _postal;
}
public void setPostal(string postal)
{
_postal = postal;
}
public string getDescription()
{
return _description;
}
public void setDescription(string description)
{
_description = description;
}
public override void save() //Call the method save() in the interface ISaveData(), the overload of the save() method, due to polymorphism
{ //Subclass ExtendedProfile can customize and modify the save() method
string _document = "d:\myweb2\saidy.xml";
XmlTextWriter writer = null; //Save as an Xml file
try
{
writer = new XmlTextWriter(_document,null);
writer.Formatting = Formatting.Indented;
writer.WriteStartDocument(false);
writer.WriteDocType("Profile",null,null,null); //Indicates <!DOCTYPE Profile>
writer.WriteStartElement("Profile"); //Generate root element
writer.WriteElementString("firstname",_firstname); //Generate sub-element <firstname>_firstname</firstname>
writer.WriteElementString("lastname",_lastname);
writer.WriteElementString("phonenumber",_phonenumber);
writer.WriteElementString("address1",_address1);
writer.WriteElementString("address2",_address2);
writer.WriteElementString("city",_city);
writer.WriteElementString("state",_state);
writer.WriteElementString("postal",_postal);
writer.WriteEndElement();
writer.Flush();
writer.Close();
}
catch(Exception ee)
{
Console.WriteLine("Exception:{0}",ee.ToString());
}
}
}
}