How to keep and add items in a List of objects during button click events
I want to add new items to my generic list when user clicks on a button, but each the the list contains only the last introduced item, it seems that during each button click list get reinitialized :(.

 This is a part of code:

 

     List<ProdusBon> listaProduseBon = new List<ProdusBon>();

    protected void Page_Load(object sender, EventArgs e)
    {
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        listaProduseBon.Add(new ProdusBon(-1, Int32.Parse(TextBox2.Text), -1, Int32.Parse (ListBox1.SelectedValue)));
    }


I also tried using this code:

     List<ProdusBon> listaProduseBon = null;

    protected void Page_Load(object sender, EventArgs e)
    {
     if (!Page.IsPostBack)
        {
           listaProduseBon = new List<ProdusBon>();
        }
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        listaProduseBon.Add(new ProdusBon(-1, Int32.Parse(TextBox2.Text), -1, Int32.Parse (ListBox1.SelectedValue)));
    }

but in this case a null reference exception was raised. 

I must keep all the items in the list and not only the last one, and when click event was raised a new item to be added to the list.

All the controls in Default.aspx got the default values only the ListBox has "Enable AutoPostBack" set to true but i believe that this is not causing this behavior.

I do not how to keep the items in the list in these conditions, please give me a hand if you know how to do this.

Thanks !
How to keep and add items in a List of objects during button click events
===

I want to add new items to my generic list when user clicks on a button, but each the the list contains only the last introduced item, it seems that during each button click list get reinitialized :(.

 This is a part of code:

 

     List<ProdusBon> listaProduseBon = new List<ProdusBon>();

    protected void Page_Load(object sender, EventArgs e)
    {
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        listaProduseBon.Add(new ProdusBon(-1, Int32.Parse(TextBox2.Text), -1, Int32.Parse (ListBox1.SelectedValue)));
    }


I also tried using this code:

     List<ProdusBon> listaProduseBon = null;

    protected void Page_Load(object sender, EventArgs e)
    {
     if (!Page.IsPostBack)
        {
           listaProduseBon = new List<ProdusBon>();
        }
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        listaProduseBon.Add(new ProdusBon(-1, Int32.Parse(TextBox2.Text), -1, Int32.Parse (ListBox1.SelectedValue)));
    }

but in this case a null reference exception was raised. 

I must keep all the items in the list and not only the last one, and when click event was raised a new item to be added to the list.

All the controls in Default.aspx got the default values only the ListBox has "Enable AutoPostBack" set to true but i believe that this is not causing this behavior.

I do not how to keep the items in the list in these conditions, please give me a hand if you know how to do this.

Thanks !