Hashtable is nothing but a collection of objects. To get brief idea,
Take a few instance of Name Class and add them to a Hashtable. Your Name will be value for Hashtable but you need to decide about key. key will unique in the Hashtable. When you are retrieving values from Hashtable this key place a major role.
First thing you need to add is namespace for Hashtable.
using System.Collections;
then take few instance of your class Name.
//Creating few instances for Class Name
Name emmu = new Name("Emmaneale", "Mendu");
Name vamshi = new Name("Vamshi", "Malyala");
Name pradeep = new Name("Pradeep", "Kandula");
We got our Values ready. So lets use initials as our key to insert into Hastable as shown below.
//Add Names into Hashtable
Hashtable SampleHashtbl = new Hashtable();
SampleHashtbl.Add("EM", emmu);
SampleHashtbl.Add("VM", vamshi);
SampleHashtbl.Add("PK", pradeep);
here if you try to use duplicates for key. You will get an error as shown in Figure 1.
Figure 1
Done with inserting. Now lets retrieve them and display on our page.
//Retrieve Names from Hastable
Name ex = (Name)SampleHashtbl["EM"];
if (ex != null)
Response.Write(ex.FullName + "<br/>");
else
Response.Write("NOT FOUND<br/>");
To retrieve we need key string. If it didn't found the key it returns null. So check before display.
That's a small example on Hashtable.
Here is the Complete Code and Output in Figure 2.
protected void Page_Load(object sender, EventArgs e)
{
//Creating few instances for Class Name
Name emmu = new Name("Emmaneale", "Mendu");
Name vamshi = new Name("Vamshi", "Malyala");
Name pradeep = new Name("Pradeep", "Kandula");
//Add Names into HashTable
Hashtable SampleHashtbl = new Hashtable();
SampleHashtbl.Add("EM", emmu);
SampleHashtbl.Add("VM", vamshi);
SampleHashtbl.Add("PK", pradeep);
//Retrieve Names from HasTable
Name ex = (Name)SampleHashtbl["EM"];
if (ex != null)
Response.Write(ex.FullName + "<br/>");
else
Response.Write("NOT FOUND<br/>");
ex = (Name)SampleHashtbl["VM"];
if (ex != null)
Response.Write(ex.FullName + "<br/>");
else
Response.Write("NOT FOUND<br/>");
ex = (Name)SampleHashtbl["PK1"];
if (ex != null)
Response.Write(ex.FullName + "<br/>");
else
Response.Write("NOT FOUND<br/>");
}
public class Name
{
string FirstName;
string LastName;
//Constructor for our Class
public Name(string first, string last)
{
FirstName = first;
LastName = last;
}
//public property for FullName
public string FullName
{
get
{
return FirstName + " " + LastName;
}
}
}
Figure 2
Emmaneale Mendu
.Net Developer
