Transparencies - Quickly Made Up A Class That Inherits Listboxes And Uses
Aug 10, 2010I have quickly made up a class that inherits listboxes and uses
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I have quickly made up a class that inherits listboxes and uses
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I've been creating short test apps repeatedly to try to understand some of the concepts in VB.NET.For the most part it has been illuminating.I read Bucky's .NET knowlegebase tutorial on passing objects as parameters to newly created forms. He shows how to create a new class that inherits from the base form class and define a New() method with parameters Extending the concept I thought about doing the same thing with a form that was created at design-time (In this case Form2).
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If Class X is within the scope of Class Y, is X a subclass of Y?If Class A is a sub Class of B, then is Class B considered a super class of A?if Class C inherits Class D is Class D a superclass or parent of Class C?if Class E extends Class F then we can consider Class E a child of F?if Class G inherits Class H and is within the scope of Class I then who is the parent of Class G? Classes that inherits Class J and classes that are within Class J are all sub classes of Class J?
View 1 RepliesI am trying to create a class in VB.NET which inherits a base abstract class and also implements an interface. The interface declares a string property called Description. The base class contains a string property called Description. The main class inherits the base class and implements the interface. The existence of the Description property in the base class fulfills the interface requirements. This works fine in C# but causes issues in VB.NET.
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If I have a class that inherits another class in which there are objects that are disposed in the dispose() procedure, do I use mybase.dispose? ex Class A inherits Class B. [code]
View 2 RepliesI think I remember reading somewhere that it was possible to assign items to a variable if the item inherited from a base class, but I can't remember how.
I want to have a class that gets properties set and one of the properties is an error code property. I want to assign any exceptions that occur to the property, but it could be any type of exception. I remember that all exceptions inherit from the Exception class.
How can I assign an exception to a property based on the class it inherits from?
I'm extending the ComboBox class in VB.NET and I'm running into a problem prepopulating the collection. I try to do so by using Me.Items.Add() calls in the New() sub. However, once I place the control on a form in the form designer, Visual Studio automatically adds those items to the collection in form designer, then they are added again at runtime. How can I make them only added once?
View 1 RepliesI have a class that inherits from the picturebox class, is represents a gauge. In that class I have an overriden function : [code]and I have on my screen what I expected. But in my form I have a timer that generates a new value for the gauge.[code]For some reason the refresh doesn't work. The gauge doesn't change, the overriden onpaint doesn't get triggerd again. anybody has any idea why?
View 12 RepliesI have a base class called PageBase and then a derived class TestPage that inherits from PageBase. In PageBase I have overridden the OnInit() and when it is called and I inspect the value of 'Me', it is of the type of the derived class and not the base class. My question is how does inheritance really work? For instance, when instantiating TestPage does an instance of PageBase get created too?
Here is my code;
Partial Public Class TestPage
Inherits PageBase
Public Sub New()
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I have created 3 classes which inherits from(System.Collections.Specialized.NameObjectCollectionBase)
The first class "SQLCommandsCollection" stores "SQLCommands" in a collection.
The second class "SQLTableNamesCollection" stores "SQLCommandsCollection" objects in its collection.The Third class "SQLDBNamesCollection" stores "SQLTableNamesCollection" objects in its collection.
Ultimately I will sit with a "SQLDBNamesCollection" collection which contains all Table names and its respective SQLCommand objects.
I would like to store this "SQLDBNamesCollection" object in my.settings("QueryViewerQueriesPerTableNamePerDBName")
at runtime but I am unsure what this settings type should be.
I have tried system.oject but this does not seem to work as I get an "Unable to cast object of type 'System.String' to type 'Fusion.SQLTableNamesCollection'" exception when I try to retrieve from settings. See below code.
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When I write the following statement in VB.Net (C# is my normal language), I get an "end of statement expected" referring to the "Implements" statement.
<Serializable()> _
<XmlSchemaProvider("EtgSchema")> _
Public Class SerializeableEntity(Of T As {Class, ISerializable, New}) _
Implements IXmlSerializable, ISerializable
...
End Class
The C# version that I'm trying to emulate is:
[Serializable]
[XmlSchemaProvider("MySchema")]
public class SerializableEntity<T> : IXmlSerializable, ISerializable where T : class, new()
{
....
}
Sometimes in my web applications I used to get this sort of error, I have no clue why is it coming however if I refresh the page few times the page is loading normally.I am using .net framework 2.0 and visual web developer 2005.
View 1 RepliesI have a window service that Inherits System.ServiceProcess.ServiceBase. While running in debug mode (havent tested compiled), the thread does not see the current user credentials. I need the credentials so I can set up the WebProxy and I would prefer to use the account that service is running under instead of passing the user and pwd as a string.Can someone help me figure out why the code running in the class the inherits from ServiceBase does not have have the credentials of the logged in user?
View 1 RepliesI have made a class using New->Class Library. I have 2 constructors, 1 function (that computes length of circle), one subroutine that computes area of circle, and main subroutine.
Public Class Class1
Class Circle
Dim rad As Double
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My problem is when I try to run the program: No errors of syntax.
What I must do? I need to right click in solution explorer add new item->add->class and copy here this code?
After I write the code I chose from the vb menu: Build->Build Solution_name
Before writing the code I choose File->New->and selected class library then save all to save as a project.
Or class library is only a dll file that runs with a windows forms application. (that is added after i write the code for write library).
I have made a class that represents people. When I create a new person, it causes an warning saying "Variable 'NewPerson' is used before it has been assigned a value. A null reference exception could result at runtime"
HOW I have tried to fix it.
I have tried adding value to many of the properties, but it still says that.
WHAT it is like.
It is almost like I have a string with a value of null.
I created this function to remove vbCrLf from the values of properties in a Custom Class:(vTransaction)
Public Function ValidateTransaction(ByRef vTransaction)
Dim property1 As String
Dim value1 As String
For Each p As System.Reflection.PropertyInfo In vTransaction.GetType().GetProperties()
If p.CanRead Then
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Throughout testing I can verify that vbCrLf is being replaced with a space as expected. When I re-examine vTransaction the changes have not been retained and the vbCrlf's are still there. What do I need to do to retain the changes being made to values in vTransaction.
Is it possible to save into temp data a user made class? I have a class with many structures and each structure contains variables and im trying to add to my program a way to save the data of that class object with its structures and everything is that possible? I tried manually making some sort of save but its taking too long and proving way too hard for me. Is there a way to just convert it into some general object format and save the object? Is that possible can you just save undefined objects without having to create a format manually for that object?
View 6 RepliesI am just testing how to use dll and after googling a lot, I made it work partially...Created new project Class Library, named it myFirstDll and made a Public Shared Sub helloDll to do something. Now since this is my first time, the dll is simply showing the input in a msgbox:
Public Shared Sub helloDll(ByVal msg As String)
If msg <> "" Then
MsgBox(msg, MsgBoxStyle.OkOnly, "WE HAVE SOME MSG")
Else
MsgBox(msg, MsgBoxStyle.OkOnly, "NO MSG")
End If
End Sub
After building the dll-file, I started a new project using normal windows forms, named it "useMyDll", I clicked Project -> Add Reference, and added my dll. The program file that I made needed a textbox and a button for using the dll:
Private Sub useDllButton1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles useDllButton1.Click
Dim msg As String = Nothing
msg = TextBox1.Text
myFirstDll.myFirstDLL.helloDll(msg) 'this will be in msgbox in dll-file
End Sub
And when running this I could write something in the textbox and a msgbox with that input would pop up. Really happy with that. My first attempt to make a dll and use it was very successful. Then I thought, what about running the dll from rundll32.exe? It would be handy to make a dll that could be run without my exe. After googling a long time, I tried to add a new button:
Private Sub useDllButton2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles useDllButton2.Click
'Now let us see if we can open it using rundll32.exe ?
Dim msg As String = Nothing
msg = TextBox1.Text
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Now the first button still works just fine, but the second button gives some error (translated to english would be) like "missing entry: helloDll" I also tried to open with command prompt, same result.
After googling again I read one place that you can't run a visual basic dll with rundll32.exe, so is this true? Or is there some way of doing it? I read one place that it works if you make the dll be "COM-Visible", but I don't really understand how to or what it means. I tried to open properties, clicked Assembly Information, and "Make assembly COM-Visible", but this doesn't change anything. Then I read somewhere that it has to be in a module to work. Could it be that I need to rewrite some codes and it would work, or would I have to start learning c++ in order to accomplish this?
So I made a Listbox, and also a custom class called "Enemies". I used a Bindingsource to Bind "Enemies" to the Listbox. "Enemies has three properties which are: "Name as String, Health as String, and Dead as Boolean".The thing I need is when I add a Enemy to the listbox, I want the BackColor of the item to either be Red or Green, depending on if the Item.Dead property is false or true.
View 2 RepliesI'm getting 'Catch' cannot catch type 'Object' because it is not 'System.Exception' or a class that inherits from 'System.Exception'. and 'Expression detected' Code underlined in blue: Catch obj1 As Object When (?)
Private Sub OpenJAMem()
Dim num3 As Integer
Try
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I have three classes Employee, Manager and Salesman. Manager and Salesman classes inherits Employee class.
Employee :
Public MustInherit Class Employee
' Field data.
Protected empName As String
Protected empID As Integer
Protected currPay As Single
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Manager :
Public Class Manager
Inherits Employee
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Salesman :
Public Class Salesman
Inherits Employee
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Now I have created a object of salesman and manager using the following code:
Dim objSalesMan as Employee=new Salesman("xyz",1,2000,5000)
Dim objManager as Employee=new Manager("abx",2,5000,"production")
Is this a good programming pratice or should I use:
Dim objSalesMan as new Salesman("xyz",1,2000,5000)
Dim objManager as new Manager("abx",2,5000,"production")
I want to develop an application using VB.Net to detect the arrival of USB Key once it's plugged into the USB port. I used a method by getting the list of all drives in the computer and then I check whether the type of the drive is "Removable Disk" and "Is ready" or not!. By using this method, I can figure out which drive is Removable drive. BUT I get confused with the FLOPPY Drive because it's also a type of Removable drive.
View 1 RepliesIn certain error situations within my VB 2008 code, I need to quickly terminate the program. This should be simple, but I haven't been able to figure out how to do it.
View 5 RepliesI found information about how to fade images on the net. But it is extremely slow. Here is the code:A is an ImageAttributes variable. matrixEl is the float value that is incremented to fade in the image.
View 6 RepliesI'm working on a program that has to continue functioning even if the SQL database isn't available. If the user has sufficient rights they can continue on using manually entered values.
The way I'm doing this it takes a very long time to fail before this can happen. Is there a way to quickly, or continually, determine if the SQL database is available so that I can avoid trying the stored procedure if it isn't?
Dim tblSteps As DataTable = New DataTable
Dim StepsBindingSource As New BindingSource
Private Sub cmdExecuteSproc(ByVal SO_Number As String, ByVal Prev_SO_Number As String)
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I am currently writing a program and I have all the windows in three languages. Is there any way of quickly changing through the languages? I mean, I can do it manually but the list has like 500+ languages and I was wondering if there was any keyboard shortcut to switch between the used languages, or any way to put a buttom on the toolbar.
View 4 RepliesI'm translating from C# to vb.net and this flags as an error: Classes can only inherit from other classes.
on this 3rd line:
Namespace Microsoft.Expression.Web.AddIn
Public MustInherit Class DocumentEventHandler
Inherits HTMLDocumentEvents
Implements IDisposable
Any idea where this class is? Do I need to import
This is the whole code:
' Copyright (C) Microsoft Corporation. All rights reserved.
'
' Description:
' AddInDocEvent handler - Subclassed from DocumentEventHandler with
' the document events the add-in cares about overridden
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I'm not understanding why its not seeing any of the objects or methods under Microsoft.Expression.Web.Interop.Designer ?
I using Microsoft.Office.Interop.Excel I get returned a 2D array of type object[,] which contains double for elements. Note that the index lower bound is 1 instead of the default 0, but I can deal with that easily. How can nicely convert the array into double[,] using .NET 3.5. (by nicely I mean concise, or compact).
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I am working on a application that stores videos, images and files. I would like to give the user the possibility to encrypt them. I am tying to use AES to encrypt them but the problem is that the decryption takes to long.I was hoping that the loading time from the hard disk of the encrypted file was far longer than the process of decryption of an image for example but i was wrong
So if i try to 1) load the image 2)decrypt it and 3)load it in a image control it takes 15 times more time that loading the original file not encrypted
I saw the video from microsoft teaching the techique of programming and found out they can comment multiple line and the same time.
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