overwrited class property not updated in the control.I have the following custom dgv:
Public Sub New()
MyBase.New()
Me.AllowUserToAddRows = False
Me.AllowUserToDeleteRows = False
Me.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle
Me.EnableHeadersVisualStyles = False
[Code]...
Is there a (simple) way to connect a textbox, label etc. to a property in a class?I have a project with a complex series of dialogs to enter data into a list of a costum class describing an experiment with many parameters that are stored as properties (both simple variables such as strings and integers, but also more complex ones).I need both to be able to update the list of my experiment class, but also to go the other way to populate the dialogs from the class.It can of course be done outside the class and the dialogs in separate subroutines. This however, quicly becomes unmanagable and hard to maintain as the dialogs and experiment class is expanded with new elements.If there was a simple way to connect say a textbox or label in a dialog with the appropriate property holding the information it would make it much easier.
View 5 RepliesIf we say blue is the default colour of the Backcolor property I understand it as if you don't specify a colour for Backcolor blue will be its colour. But I could not make sense of default property of a class in the context of building a custom user control. After calling an instance of a class we have to either call one of its members or assign an other object for it. Therefore why should there be a default property?
View 9 RepliesHaving trouble with properties in a Class, demonstrated by the code below.If create a class (person) that has another class (address) as a property and set the elements of the address, the set method on the first class never gets called.It also allows the property to be updated although the set method prevents this.
Module Module1
Class PostalAddress
Property Street1 As String[code]....
Is it possible to create a user control with a list of custom class type property? If it is, how can I? The issue is that, in designer mode the property is not displayed in property window. I can add the list on markup but when i switch to the designer mode it gives an error which is 'The user control does not have a public property named BookList'.
View 1 RepliesWhen inheriting class or control e.g. ListView, TreeView, etc..., what is the best way to distinguish between built-in methods/property/events and mine?
Currently, i start my methods/property/events with "aa" in order to make them at the top of auto complete list.
I need some help to understand my options to get this working. I try to update a textbox control by a property-changed event from a class variable. I've digged around for a day and have a vague understanding that this can be solved in three ways:
1. Using some "if InvokeRequired", "Invoke" code in the handler method
2. By programming a special delegate class for this variable
3. By using a databinding directly linking the control (textbox) to the class event
Now.. Are these options correct? And would it be possible to get some help to show these three solutions in actual code (relevant to mine)? I can't seem to manage to sort all the information to a working code. Also, what are the pros and cons of the different solutions?
As my code stands now, it's obviously none of the above, as it gives a cross-thread error, as indicated.
[Code]...
I have a UI control that gets updated from two different threads using the standard delegate/Invoke thing. The problem is that the calls that go through the invoke are happening way after the calls from the main thread. I need them to update the UI in the order they where called.
[Code]...
I have a very simple class that holds a few public properties - ID, Text, Colour, etc. and a Boolean called 'SelectedItem'. Just like the Checked property on RadioButtons, only one item can have its SelectedItem property set to True within a particular group. Note: there will be several separate groups (lists), each allowed to have only one item with SelectedItem = True.
My first thought was that I would probably just have to handle everything outside of the class, setting SelectedItem to False for every other item in a particular list when another item was selected. But that seems rather inelegant to me. So I've been trying to think of how this might be done within the class. For example: could I perhaps have a private string property called say "GroupName" - set in the New sub when adding a new instance of the class - and then use a private shared method to set every item's SelectedItem property to False, provided the item has the same GroupName as the newly selected item? I would have a go at doing this but I have no idea how to enumerate every instance of a class from within that class, or whether that's even possible. Is it? Or is there another (better) way to achieve my goal? Here is a cut-down version of what I've got so far:
Public Class ResourceItem
Public ID As Integer
Public Text As String[code]....
As can be seen: instead of instantiating a new ResourceItem and passing that as an argument to the manager's Add procedure, I'm simply passing the details of the new item and the procedure is creating the item from those. I don't know whether this is a good or bad idea - please advise - but I've done it because I couldn't figure out how to make the SelectedItem property only writeable by the manager, so I wanted to avoid having directly accessible objects that could have their SelectedItem property set to True without it deselecting all the other items in the same group. Of course that still leaves the possibility of setting a variable to one of the manager's list items and setting it from there, so I would still like to know how I could prevent that, if possible.
UPDATE: I didn't use the code above in the end, deciding instead to go with Cyborgx37's solution - which seems to work perfectly well for me despite the warnings about best practice. I also realised I would need to use the same class in another scenario where multiple items could be selected, so it was easy to add a Boolean property to the manager to enable that.
I'm fairly new to ASP.NET and of course happened to stumble some strange problem. problem is very popular, but none of the replies I found worked for me.
[Code]...
And the image doesn't change. It doesn't even fire up the showphoto.aspx code.The property is changed (because next time i step into it, it's changed), but showphoto is never fired.I'm aware of image caching issues, but I can't get even one image, not mentioning have it changed.For sure there's a very simple explanation, but I'm fighting with this for 2 days now to no avail.
I have the following code:
Public Class MyColorsClass
'Constructors
Public Sub New()
'Empty Constructor
[code]....
However, if the empty constructor was called to instatiate this class then the colortype is not yet set. Therefore, if one accesses the 'IsColorCool' property it will always return 'False'. Now for the sake of this example, I must keep the empty constructor as part of the class.Now I could add some code in the 'IsPropertyCool' to check and see if a ColorType has been defined, and throw an exception if it has not been set, but I don't really want to do that.I also could always move the logic OUT of the property and into a method on the class called 'DefineIfColorIsCool' or something, and make the owness on the caller to make sure the method was called if they want to use the property 'IsColorCool'?
part of my code is in below
[Code]...
I would expect to see the path.Path include the new record, however, I also notice that tempnextgen also include the new record. Can anyone help me out on this issue? Why the tempnextgen got updated as well, how to prevent this unexpected operation?
I have a DataTable that's constantly being updated with new data from my database via a timer. That data is eventually reformatted and displayed in a DataGridView control.In an effort to prevent the DataGridView from completely refreshing from re-databinding (thus, clearing out selections, resetting scrollbars, defaulting sorting settings, and making the gridview flash as it reupdates), I'm simply removing old rows from the datagrid that no longer exist in the DataTable, and adding new rows to the datagrid that appear in the DataTable since the last update.
For the sake of simplicity, we'll call DataGridView the LEFT table, and DataTable the RIGHT table I'm looking for a way to go through both tables (LEFT and RIGHT), and remove old rows that are no longer in RIGHT and delete them from LEFT. And look for new items in RIGHT and add them to LEFT. Each table has a column called "RecID" containing a unique id for each entry that can be used for comparison. is there a way to do this all in one loop? What I'm looking for, in pseudo code:
<loop through everything>
if RecID does not exist in LEFT but exists in RIGHT
add new item to LEFT
if RecID does exist in LEFT but does not exist in RIGHT
[code]....
Supose a base class
Public Class airplane
Private var_num_seats As Integer
Private var_num_engines As Integer
[code]....
Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?
I have procedure (Import) that calls a for a new instance of frmImportData. I also have a class name clsBatch that has a data table property called prpParametersTable.For some reason, I get an error (indicated below with ERROR>>>) when trying to assign prpParameterTable to cv_dtImport2. The error states "Object reference not set to an instance of an object.". Why does this error not happen when I assign dtBP to cv_dtImport1? Both cv_dtImport1 and cv_dtImport2 are equal to Nothing and in my Import procedure dtBP = prpParametersTable.
Public Sub Import(ByVal clsB As clsBatch)
Try
Me.cv_clsB = clsB
[code]....
I have three class files, accounts.vb and transactions.vb in addition to my form.vb. I am unable to retrieve a member variable from on class from inside the other. When the combobox index changes, the program loads the correct account (checking or saving) from two different sequential files. I don't think I have the calcBalance procedure in the correct class file. And that is what I am having trouble with. Accessing it to display it. [Code]
View 1 RepliesThis is a bit of a continuation from a previous post for which AtmaWeapon was very informative.
Problem:
A parent class has a sub class with various properties. A property of the parent class is a List(of T) with T = the sub class The issue is how to store data in the sub class of the instantiated parent
Some example code (hopefully formatted correctly):
Code:
'=========== Class Definitions =============
Public Class courseClass
Public Class timeTableClass
[Code].....
I'm looking for a tutorial on how to Adding a list(of Class) or Collection as another Class's Property.What I am after is something like the Columns Collection for the DatagridView control.I would like to add Items in the graphics screen. Where the item list is displayed in the left panel and the selected Item properties are displayed in the right panel.
View 4 RepliesI have a class that has the following property that is generated by the methods in the constructor.
Public Class clsLoadTables
Private _ds As New DataSet
Public Property ds() As DataSet
Get
[CODE]........................
My problem is that I do not want to inherit this class, but I have other classes that need to access the ds DataSet property. If at all possible I would like to not use inheritance and not load my datatable more than once in the program.
Here is my failed attempt to access the property inside another class that is not inheriting clsLoadTables:
[CODE].........................
How I can access this dataset that I want to load only once in the program from many classes without using class inheritance or a global module?
I know that an interface can contain another interface within it.But;can a class contain another class within it?Can an interface contain another interface within it?
View 9 RepliesI have two classes, and for a property in one of the classes I'd like to be able to load it up with an array of the other class. However my attempt at accomplishing this results in a "Object reference not set to an instance of an object" error. I know it's a rookie mistake, but I'm stumpedssist?
My code is as follows:
Namespace Parking
Public Class garage
[code]......
bare with me during this silly example. :-) Let's say I have a class like this:
Public Class Animal
Public iLegs as int32 ' Number of legs
Public bWings as Boolean ' Wings? Yes/No
End Class
And another class that inherits the "Animal" class and adds one more property:
Public Class ScaryAnimal
Inherits Animal
Public iScariness as int32 ' 0-100, how scary is it?
End Class
Now, if I have an instance of "Animal" with some values in it, and I decide I want to cast it to a ScaryAnimal for some reason, how do I do that without having to create a new instance of "ScaryAnimal" and copy each property value?Basically I'm looking for a way to do this, without having to write the lines marked with '*** below:
[Code]...
I would like to be able to set Control visual properties such as color, boarder, flat style, etc. on the base class of the control so that as I add new instances of the control, each instance inherits the visual properties of the base. I have tried using Application Settings but it appears as though I need to reference an application setting manually each time I add the control to a form. This is a Windows Form question.
View 4 RepliesI'm trying to make a program with transparent labels over pictureboxes and when I set the label Parent to the PictureBox the position of the label changes.
View 2 Repliesi frequently have troubles with the dock property. it seems that either the order of creation or adding to the parent control determines whether or not a control's dock property supersedes another's. e.g. a control with the dockstyle fill will overlap with another docked control on the same parent. does anyone know what the rules are to determine how docking will behave; particularly in dynamically created GUIs?
View 2 RepliesIs there a way to bind the text property of a control to an expression? I have a user control that I add to a FlowLayoutPanel. You can see I have 4 controls in the FlowLayoutPanel below. The first control is a LinkLabel and the other three are my user controls which are numbered 1, 2, & 3. I'd like to bind the label that shows the 1, 2, or 3 to the user controls index within the FlowLayoutPanel.
If I happen to remove the 2nd user control I want the 3rd user control to now display 2. I could use the FlowLayoutPanel ControlAdded or ControlRemoved events, but wanted to see if I could do some binding first.
If I need access to the value of a user control's property BEFORE PreRender, would I need to base the custom control off of one of the preexisting data controls (repeater, listview,etc.)?One of my user controls features a gridview control that is configured based on the user control's properties on which it resides. Several of the key properties alter the SQL Statement for the underlying recordsource. I'm now in a situation where the property that sets the WHERE statement for the SQL Statement needs to tied to a value in the user control's parent FormView. Think of the formview as displaying a customer detail record. The user control takes the customer's account number and then displays data from a related table such as Customer Contact Names. Since the gridview is created before the control's prerender event, working within the prerender event doesn't seem efficient.
View 1 RepliesExample:
Two files - TestClass.vb, myForm.vb
TestClass.vb looks as follows:
Imports System.Threading
Public Class TestClass
Private myClassThread As New Thread(AddressOf StartMyClassThread)
[code]....
The result:Application runs, no errors or exceptions.Displayed is the listbox and the Start button.I press the start button and a msgbox says "Not Invoked" as expected and upon clicking OK to that msgbox "Start Button Pressed" is added to the Output listbox control.Immediately following that the msgbox pops up again and says "Not Invoked". I was expecting "Invoked" as a separate thread is trying to use the Output listbox control.Of course this results in the Output.Items.Add being attempted which results in no visible result as the thread is not allowed to directly update the UI control.
I am searching for the Component Class. When I go to "Add New Item" ,in my project their is no Component Class Item in VS 2008. I would like to Drag and Drop control onto my new class and I can't see how to do this ?
View 6 RepliesI am running from a problem while iterating over class properties.
I have my first class:
class Item
private _UIN as integer = 0
private _Name as string = ""
[Code]....
I get UIN, Name, ItemCategory but i expected UIN, Name and Category.
I am a bit unclear about this and dun know why this is happening? What should i do to correct it?