Object reference not set to an instance of an object.
Description: An unhandled exception occurred during the execution of the current web request. review the stack trace for more information about the error and where it originated in the code.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.Source Error:
I am trying to create a simple page with a drop down list which has 3 items. Choosing any of those 3 items calls for a specific constructor in the script. Using VB 2008
public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { } protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e) { if (DropDownList1.Text == "Coupe") { //Response.Write("You chose the Coupe"); string Engine; string Transmission; string Wheels; string Safety_Features; string Key_Systems; string Interior; string Mileage; Altima A1 = new Altima(Engine, Transmission, Wheels, Safety_Features, Key_Systems, Interior, Mileage); Response.Write(A1.displayAuto()); } if (DropDownList1.Text == "Hybrid") { Response.Write("You chose the Hybrid"); } if (DropDownList1.Text == "Sedan") { Response.Write("You chose the Sedan"); } } public class Altima { //private member variables private string Engine; private string Transmission; private string Wheels; private string Key_System; private string Safety_Features; private string Interior; private string Mileage; //public accessor methods public void displayAuto() { System.Console.WriteLine(Engine, Transmission, Wheels, Safety_Features,Key_System, Interior, Mileage); } //constructors public Altima(string Engine, string Transmission, string Wheels, string Safety_Features, string Key_System, string Interior, string Mileage) { this.Engine = Engine; this.Transmission = Transmission; this.Wheels = Wheels; this.Key_System = Key_System; this.Safety_Features = Safety_Features; this.Interior = Interior; this.Mileage = Mileage; string Engine = ("2.5-litre DOHC engine with 175 HP and 180 lb-ft of torque or 3.5-litre DOHC engine with 270 HP and 258 lb-ft of torque"); string Transmission = ("-speed manual transmission or available Xtronic CVT® with manual mode"); string Wheels = ("17 inch 5-spoke aluminum-alloy wheels (2.5 S) or 18 inch 5-split spoke aluminum-alloy wheels (3.5 SR)"); string Safety_Features = ("Six standard air bags as part of Nissan Advanced Airbag System (AABS)"); string Key_System = ("Nissan Intelligent Key® with Push Button Ignition"); string Interior = ("Leather"); string Mileage = ("Up to 5.6 L/100 km on city with eCVT"); }//coupe -------> First constructor public Altima(string Engine, string Transmission, string Safety_Features, string Mileage) { this.Engine = Engine; this.Transmission = Transmission; this.Safety_Features = Safety_Features; this.Mileage = Mileage; string Engine = ("2.5-litre DOHC engine with 175 HP and 180 lb-ft of torque or 3.5-litre DOHC engine with 270 HP and 258 lb-ft of torque"); string Transmission = ("-speed manual transmission or available Xtronic CVT® with manual mode"); string Safety_Features = ("Six standard air bags as part of Nissan Advanced Airbag System (AABS)"); string Mileage = ("Up to 5.6 L/100 km on city with eCVT"); }//sedan -----------> Second Constructor public Altima(string Engine, string Transmission, string Mileage) { this.Engine = Engine; this.Transmission = Transmission; this.Mileage = Mileage; string Engine = ("2.5-litre DOHC engine with 175 HP and 180 lb-ft of torque or 3.5-litre DOHC engine with 270 HP and 258 lb-ft of torque"); string Transmission = ("-speed manual transmission or available Xtronic CVT® with manual mode"); string Mileage = ("Up to 5.6 L/100 km on city with eCVT"); }//hybrid -----------> Third constructor } }
how do I ouput the values from the constructors when I choose the specific list box item?
Clicking the label of a drop down list, re-sets the selected value to the first item in the list. This has a history of causing data entry problems when users accidently click on the label.
In the below example ddlContactType has a selected value as 'PRIMARY' and whenever i click on the lblContactType Text, the dropdown box Selected value is changing to "Select One" Text.
How to prevent this one. It should be on PRIMARY Only.
I have a requirement in my application that, while saving the application, need to get all the value from drop down list and pass it to the view model. But application should not allow the user to select more than one item from drop down list manually, ie, only one value at a time. My view model is like ...
public class ListManagement { public IEnumerable<selectListItem> InactiveProduct { get; set; } public string[] InactiveProductSelected { get; set; } public IEnumerable<selectListItem> ActiveProduct { get; set; } }
I have a master page which has an unordered list in this way:
[code]....
These links are directed to my content pages. I am able to highligt the selected list item on hover and on active.
But I do not understand how I can highlight the selected list item as long as the user is on that specific page/link (current list item). I know that we can specify a seperate body tag and id for each of the content pages and then use CSS to highlight the current list item, but all this code rests already inside a body tag in the master page.
I've put together the following code which generates a dropdownmenu list (values from a database) in a repeater control, then adds a final item. I can make it selected, but I'd like it to appear at the top, rather than the bottom as it does now.
I have two drop down list on a page. The first one list projects and the second list users. The userlist is populated with an object datasourse that pulls a list of users for the selected Project.Whenever the Project list selection changes the second ddl Userlist always reverts to the first person in the list instead the person that was selected before a new Project was chosen.
I have a list with 2 sorts of items. Items that have actual values (1,2,3,4 etc) and items that are like group headings so all their values are set to 0. If someone decides to select a group heading - which has a value of 0, is it possible to redirect them to my 'Select an item' item which has a value of ""?
If worse comes to worse, I can just reconstruct the entire list, although if possible I'd like to avoid it.
Started checking out VS2010 Express. I have it installed on my home laptop and my work PC. This "problem" occurs on both systems. In past versions of VS I thought I was able to add style sheets to a theme by right-clicking on the theme folder, selecting "New Item...", then clicking the Style Sheet item. In VS2010 Express, Style Sheet is not present as an option. Only Skin, XML, and XSLT are present.
Is there a way to add Style Sheet to the list of selectable items? My current workaround is to create a style sheet outside of the theme folder, then drag it into the theme folder.
I use ASP.Net web form and ADO.Net.I would like to show the data list like stackoverflow because I don't want to use GridView. I've some data fields to show example.
Title Description Date Keyword
what control I should use and that control will attach with Pager for the data list.
I need to desgin a dropdown list control which can contain N number of rows (which is normal) and M number of columns inside each row (which is not very normal)
Each column will contain a special charecter, and clicking on the charecter should add that chrecter to a textbox placed along side the dropdownlist. It can be imagined as an N * M matrix inside a dropdown list.
I want to style an ASP.NET RadioList so that the list is horizontally oriented, with two rows, the first of labels, and the second of inputs, for example:
been trying long time now to style the width of columns of a checkbox list, trying to group text by similar lengths, something like this:
small width [] wider width here [] widest width of all here [] small wid [] wider width h [] widest width of all h [] small widt [] wider width her [] widest width of all her [] (of course the checkboxes line up in the actual form)
so smaller length texts are not too far away from their checkbox, the checkboxlist control seems to have an iron grip on those col widths
I have a drop down list control populated with items and some code to take the currently selected item value. The problem is I only get the value of the first item in the list regardless of what item is actually selected. Here is my code to populate the drop down:
protected void displayCreateCategories() { StoreDataContext db = new StoreDataContext(); var a = from c in db.Categories orderby c.Name select new{catName= c.Name, catId=c.CategoryID}; ddlCategory.DataSource = a; ddlCategory.DataTextField = "catName"; ddlCategory.DataValueField = "catId"; ddlCategory.DataBind(); }
To get the value of the currently selected item which in my case is always of type integer I do label1.text=Convert.toInt32(ddlCategory.SelectedValue); I get the selected value, but it is always for the 1st item in the list. I'm pulling my hair out over this.
When "Configure ListView..." in the smart tag of ListView is clicked, one can choose one of the 4 styles on the list: Colorful, Professional, etc. I am wondering if there is any way to add one's own style to the list.
If I have a specific order that I want to sort my List by, how do I do that? For instance, I have a list of items (coming from a database), with ID's ... and they come in order, i.e 1, 2, 3, 4. After receiving this list, I'd like to reorder the list above based on a specific order, e.g. 2, 4, 1, 3. How do I do this without complicate it too much?
I have a list of Controls that are held in a List<Control> and I want to be able to check their type. As my list holds only Controls, doing typeof() isn't going to get me too far, I want to be able to ask if List<Control>[0] is a Checkbox, TextBox, Label, etc.How do I go about finding out what specific type of Control I have in my list?
I am using list view to display the the data but i am getting an error like An item placeholder must be specified on ListView 'ListView1'. Specify an item placeholder by setting a control's ID property to "itemPlaceholder". The item placeholder control must also specify runat="server.Even i have specified the itemplaceholder id but no use still same error.