serialize into XML

Question

I was searching on the internet the whole while but could not find any help. My issue is to serialize an arraylist to xml. I first gather data from the database and assign it to the arraylist as follows,

    ArrayList conRc = new ArrayList();        
    while (readIp.Read())
    {
        string ipVal = readIp.GetString(0);
        string conLvlVal = readIp.GetString(1);
        string ispVal = readIp.GetString(2);
        string tsVal = readIp.GetString(3);
        ispVal = ispVal.Trim();
        ispVal = ispVal.Replace("\"", "");
        string localPortVal = readIp.GetString(4);
        string foeriegnGeoVal = readIp.GetString(5);


        conRc.Add(new Confidence(tsVal, ipVal, localPortVal, ispVal, foeriegnGeoVal, conLvlVal));


    }

and trying to serialize the arraylist as follows,

    System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(ArrayList));
    System.IO.TextWriter writer = new System.IO.StreamWriter(@"F:\myItems.xml", false);
    serializer.Serialize(writer, conRc);
    writer.Close();

but i get an error saying,

There was an error generating the XML document.

May I know how to perform this task please..it ll be a great help.

FYI, below is the Confidence class,

public class Confidence
{
    private string ip;

    public string Ip
    {
        get { return ip; }
        set { ip = value; }
    }
    private string count;

    public string Count
    {
        get { return count; }
        set { count = value; }
    }

    private string isp;

    public string Isp
    {
        get { return isp; }
        set { isp = value; }
    }
    private string colColor;

    public string ColColor
    {
        get { return colColor; }
        set { colColor = value; }
    }

    private string timeStamp;

    public string TimeStamp
    {
        get { return timeStamp; }
        set { timeStamp = value; }
    }

    public string Port
    {
        get { return port; }
        set { port = value; }
    }

    public string ForeignGeo
    {
        get { return foreignGeo; }
        set { foreignGeo = value; }
    }

    private string port;

    private string foreignGeo;
    public Confidence(string timeStampVal, string ipVal, string portVal, string ispVal, string foreignGeoVal, string countVal)
    {
        this.timeStamp = timeStampVal;
        this.ip = ipVal;
        this.port = portVal;
        this.isp = ispVal;
        this.foreignGeo = foreignGeoVal;
        this.count = countVal;
    }


    public Confidence(string ipVal, string countVal, string ispVal, string colorVal, string timestampVal)
    {

        this.ip = ipVal;
        this.count = countVal;
        this.isp = ispVal;
        this.colColor = colorVal;
        this.timeStamp = timestampVal;
    }

    public Confidence(string ispVal)
    {

        this.isp = ispVal;

    }
}

EDIT

Prevoiusly the error was due to the missing parameterless constructor, as Alex Filipovici suggested, but now i get a new error as follows,

[InvalidOperationException: The type Confidence was not expected. Use the XmlInclude or SoapInclude attribute to specify types that are not known statically.]
   System.Xml.Serialization.XmlSerializationWriter.WriteTypedPrimitive(String name, String ns, Object o, Boolean xsiType) +1151604
   Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterArrayList.Write1_Object(String n, String ns, Object o, Boolean isNullable, Boolean needType) +465
   Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterArrayList.Write2_ArrayOfAnyType(Object o) +271

[InvalidOperationException: There was an error generating the XML document.]
   System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id) +651
   System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o, XmlSerializerNamespaces namespaces) +72
   System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o) +10
   Dashboard.getDataOutTable() in c:\Users\DELL\Documents\Visual Studio 2010\WebSites\Dashboard\Dashboard.aspx.cs:1035
   Dashboard.Page_Load(Object sender, EventArgs e) in c:\Users\DELL\Documents\Visual Studio 2010\WebSites\Dashboard\Dashboard.aspx.cs:59
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +51
   System.Web.UI.Control.OnLoad(EventArgs e) +92
   System.Web.UI.Control.LoadRecursive() +54
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +772

Answer 1

First error : no default constructor in Confidence

=> Add in Constructor class :

public Confidence()
{
}

Second error : Serializer don't recognize type of ArrayList. => modify Serializer :

 System.Xml.Serialization.XmlSerializer serializer = new System.Xml.Serialization.XmlSerializer(typeof(ArrayList),
 new System.Type[] { typeof(Confidence) });

Answer 2

If you take a look at the inner exception you'll see that you have to add a parameterless constructor to the Confidence class:

public class Confidence
{
    public Confidence()
    {

    }

    // other class members
}

For the subsequent exception, try using this constructor:

System.Xml.Serialization.XmlSerializer serializer = 
    new System.Xml.Serialization.XmlSerializer(typeof(ArrayList), 
    new Type[] { typeof(Confidence) });