Working with ArrayList PART 1

ArrayList

File->New-> Project-Console Application

using System.Collections;

It is the namespace which  is used.

Output

Add Method
It will add the element as object in the Array List. These Objects are stored in heap.

GridView with DataSet ,DataTable, DataReader

DataBase Design

Default.aspx

Default.aspx.cs


protected void Button1_Click(object sender, EventArgs e)
    {
        /* dataset */
        con = new SqlConnection("user id=sa;password=uday;database=uday;data source=localhost");
        cmd=new SqlCommand("select *from customers", con);
        con.Open();
        da=new SqlDataAdapter(cmd);
        ds = new DataSet();
        da.Fill(ds,"customers");
        GridView1.DataMember = "customers";
        GridView1.DataSource = ds;
        GridView1.DataBind();
        con.Close();
    }


protected void Button3_Click(object sender, EventArgs e)
    {
        /* DataTable */
        con = new SqlConnection("user id=sa;password=uday;database=uday;data source=localhost");
        cmd = new SqlCommand("select *from customers", con);
        con.Open();
        da = new SqlDataAdapter(cmd);
        dt = new DataTable();
        da.Fill(dt);
        GridView1.DataSource = dt;
        GridView1.DataBind();
        con.Close();
    }

protected void Button2_Click1(object sender, EventArgs e)
    {
        /* datareader */
        con = new SqlConnection("user id=sa;password=uday;database=uday;data source=localhost");
        cmd = new SqlCommand("select *from customers", con);
        con.Open();
        SqlDataReader dr;
        dr = cmd.ExecuteReader();
        GridView1.DataSource = dr;
        GridView1.DataBind();
        con.Close();
    }

Output:

Access Specifiers in C#.

They are used to define scope of the Class or its Members i,e who can access it and who cannot Access it.

Here we will discuss about each access specifier with an example. 

.Net Supports five Access Specifiers.

1 Public.
2 Private.
3 Protected.
4 Internal.
5 Protected Internal.


public:

So any member declared as public can be accessed from the outside the class.

We can access from other class using object reference.

Example 

File-New- Project- Console Application.

In the above example we have created a object in Derived Class , since the variable is public it can be accessed from outside the class.

output

private

Members declared as private are not Accessible outside the class.

A class under Namespace cannot be declared as private.

Example 

Output:

Example for Public and Private Access Specifier.

output

2 Example

output 

Protected

If the members are declared as  protected , then they can be accessed only From the child class., it is same as private.

Note: A class under Namespace cannot be declared as private. 
This access specifier is used when we need to use Inheritance in the program.

output

Another Example of working with Protected Access Specifier.

Internal

Members are declared as internal under a class than they r accessible only with in the Project either from the Child Class or a Non Child Class. These are accessible only within the Assembly.

internal  is the default Access Specifier for the Class.

output

Protected Internal 

Members declared as ProtectedInternal under a Class enjoys Dual Scope. i,e with the project they behave as internal members and provide access to all the classes, outside the project they change to Protected and still provide access to there child classes.

Output:

Add a new project under the solution of type Console Application, name it as ConsoleApplication2 & rename the default file Program.cs as Four.cs so that class name also changes as Four, now write the following code in it by adding the reference of ConsoleApplication1 assembly from its physical location.

ICALL BACK EVENT HANDLER

We have to play with 4 functions,

Two client side functions i.e. java script function, 
JavaScript Functions
RaiseCallbackEvent function gets call automatically whenever there is a CallbackEvent. And after this function 2nd function i.e. GetCallbackResult get called automatically.
DataBase Design
<html xmlns="http://www.w3.org/1999/xhtml">
    function ReceiveServerData(retValue) {
using System.Data.SqlClient;
public partial class AddPage : System.Web.UI.Page,ICallbackEventHandler
    }
    public void RaiseCallbackEvent(String eventArgument)
Output


Two server side function i.e. c# (in this case).

1 function ReceiveServerData(retValue)
2 function Checkusername 

.cs functions

1  public void RaiseCallbackEvent(String eventArgument)

2  public String GetCallbackResult()

AddPage.aspx

<head runat="server">
    <title></title>
    <script type="text/javascript" language="javascript">
    function Checkusername ()
    {
        var values = document.getElementById("txtEname").value;
        CallServer(values, "");
    }

        if (retValue == "N") {
            alert("Please select another name; empname already exists");
            document.getElementById("txtEname").value = "";
            document.getElementById("txtEname").focus();
        }
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <table>
    <tr>
    <td>
        <asp:Label ID="Label1" runat="server" Text="Eno"></asp:Label>
    </td>
    <td>
        <asp:TextBox ID="txtEno" runat="server"  ></asp:TextBox>
    </td>
    </tr>
        <tr>
    <td>
        <asp:Label ID="Label2" runat="server" Text="Ename"></asp:Label>
    </td>
    <td>
        <asp:TextBox ID="txtEname" runat="server" onblur="javascript:Checkusername()"></asp:TextBox>
    </td>
    </tr>
    <tr>
    <td>
     <asp:Label ID="Label3" runat="server" Text="Designation"></asp:Label>
    </td>
    <td>
     <asp:TextBox ID="txtDesignation" runat="server"></asp:TextBox>
    </td>
    </tr>
    <tr>
    <td colspan="2" align="center">
        <asp:Button ID="btnSave" runat="server" Text="Save" onclick="btnSave_Click" />
    </td>
    </tr>
    </table>
    </div>
    </form>
</body>
</html>

AddPage.aspx.cs

using System.Configuration;

{
    protected String returnValue;
    protected void Page_Load(object sender, EventArgs e)
    {
        String cbReference = Page.ClientScript.GetCallbackEventReference(this, "arg","ReceiveServerData", "context");
        string callbackScript = "function CallServer(arg,context)" + "{" + cbReference + ";}";
        Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "CallServer", callbackScript,true);
    }
    protected void btnSave_Click(object sender, EventArgs e)
    {
        SqlConnection con = new SqlConnection("user id=sa;password=uday;database=uday;data source=localhost");
        con.Open();
        SqlCommand cmd = new SqlCommand("insert into employee values(" + txtEno.Text + ",'" + txtEname.Text + "','" + txtDesignation.Text + "')", con);
        int i=cmd.ExecuteNonQuery();
        if(i>0)
        {
            Response.Redirect("Default.aspx");
        }
        con.Close();


    {
        SqlConnection con = new SqlConnection("user id=sa;password=uday;database=uday;data source=localhost");
        SqlCommand com = new SqlCommand("select *from employee where ename='" +eventArgument + "'", con);
        con.Open();
        SqlDataReader dr;
        dr = com.ExecuteReader();
        if (dr.HasRows == true)
        {
            returnValue = "N";
        }
        else
        {
            returnValue = "Y";
        }
        con.Close();
    }
    public String GetCallbackResult()
    {
        return returnValue;
    }
}

Working with JSON

JSON (JavaScript Object Notation) is one lightweight data exchange format.

You don’t need to download an additional library to serialize/deserialize your objects to/from JSON. Since .NET 3.5, .NET can do it natively.

Add a reference to your project to “System.Web.Extensions.dll”

File->New->Website

Add a Class(Static.cs)

Now write the Following Code in Static.cs 
using System;
/// <summary>
    public String Technologies()
    public ArrayList EmpDetails()
    public string JsonString()
Now Add New Item
Default.aspx
<html xmlns="http://www.w3.org/1999/xhtml">
Default.aspx.cs
using System.Web.UI;
public partial class Default3 : System.Web.UI.Page
Now Run
Paste the following output and Click on Viewer
using System.Web.UI;
public partial class Default3 : System.Web.UI.Page

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Script.Serialization;

using System.Collections;

/// Summary description for Static

/// </summary>

public class Static

{

    JavaScriptSerializer jss = new JavaScriptSerializer();

    {

        string jsonString = string.Empty;

        string[] courses = { "asp.net", "sqlserver", "silverlight", "sharepoint", "iPhone", "vb.net", "java", "php" };

        Dictionary<string, string[]> dicEmpInfo = new Dictionary<string, string[]>();

        dicEmpInfo.Add("Technologies", courses);

        jsonString = jss.Serialize(dicEmpInfo);

        return jsonString;

    }

    {

        Dictionary<string, string> dicpersonalinfo = new Dictionary<string, string>();

        dicpersonalinfo.Add("First Name", "Uday");

        dicpersonalinfo.Add("LastName", "Kumar");

        Dictionary<string, string> dicpersonalInfo2 = new Dictionary<string, string>();

        dicpersonalInfo2.Add("FirstName", "Anvesh");

        dicpersonalInfo2.Add("LastName", "G");

        Dictionary<string, string> dicpersonalInfo3 = new Dictionary<string, string>();

        dicpersonalInfo3.Add("FirstName", "Sunitha");

        dicpersonalInfo3.Add("LastName", "Kumari");

        Dictionary<string, string> dicpersonalInfo4 = new Dictionary<string, string>();

        dicpersonalInfo4.Add("FirstName", "Badri");

        dicpersonalInfo4.Add("LastName", "Nath");

        ArrayList empDetails = new ArrayList();

        empDetails.Add(dicpersonalinfo);

        empDetails.Add(dicpersonalInfo2);

        empDetails.Add(dicpersonalInfo3);

        empDetails.Add(dicpersonalInfo4);

        //string strJson = jss.Serialize(empDetails);

        return empDetails;

    }

    {

        string jsonString1 = string.Empty;

        ArrayList arr = EmpDetails();

        jsonString1 = jss.Serialize(arr);

        return jsonString1;

    }

}

<head runat="server">

    <title></title>

</head>

<body>

    <form id="form1" runat="server">

    <div>

    </div>

    </form>

</body>

</html>

using System.Web.UI.WebControls;

{

    protected void Page_Load(object sender, EventArgs e)

    {

        Static obj = new Static();

        string str = obj.Technologies();

        Response.Write(str);

    }

}

Now Go to 

http://jsonviewer.stack.hu/

For Second Method in static.cs

Default.aspx.cs

using System.Web.UI.WebControls;

{

    protected void Page_Load(object sender, EventArgs e)

    {

        Static obj = new Static();

        string str = obj.Technologies();

       // Response.Write(str);

        string str1 = obj.JsonString();

        Response.Write(str1);

    }

}

copy the output and 

Now Go to 

http://jsonviewer.stack.hu/