I need to do something like this Class A End Class Class B Inherit A End Class A=B If i try i get an exception! that i can not cast B in A. How can I overcome this problem? I need to define 2 classes B identical to A but as a distinct class What I need is to be able to cast one class to the other like A=B or B=A I tried with directcast but i got the exception what can I do
View 1 RepliesI'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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Is there a way to define a class such that there can be only a single instance of that class?
View 5 Repliesbelow is my code to use binarywriter it work fine on class form1 level
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Interface Iinterface
Sub myMethod()
End Interface
class myCls implements Iinterface
End Class
i did this and i wanted to define the myMethod() within the class myCls but i am getting an error in this line:
class myCls implements Iinterface
error:end of statement required
I would like to define a class as something like a constant, and use the class directly rather than having to always create an instance. Is this possible? I've tried a handful of combinations of syntax, but nothing I've tried lets me do what I'm after. To give an idea of what I'm after:
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I need to define a property in my class which is an array (of doubles).My original (bad) version is this:
Public Class Market
Property Correlations0 As Double
Property Correlations1 As Double
Property Correlations2 As Double
[code].....
This however doesn't work. I get an error already at design time: "Public Property Correlations as Double has no parameters and its return type cannot be indexed."What should I do with it? I also do not know in advance how large the array should be (the array size is determined at runtime based on other properties).
I'm developing a software that handles very specific regional standards. In one part of the country they have different standards for entering this data than they do in other parts of the country. In fact there are hundreds or thousands of possible configurations that would be best in various regions.
The solution I've come up with is to write a program that can load different control configurations with the supporting code to its main form at runtime. I do not know how to accomplish this. Would I use visual inheritance at runtime? Would I use a plugin system? I just need to potentially allow a power user to design thier own interface or to modify an existing interface to better suit thier needs.
Edit: Is there a way to define the base class of a form at runtime? Could I create user controls in a plugin and pass them in to the host program?
I was just practicing some coding and noticed that I was able to use class instead of Module in VB .NET. So I replaced my module to class and I got this error message:No accessible 'Main' method with an appropriate signature was found in 'practicevb'.practicevb
I made sure that the startup object was set correctly in Properties > Application > Startup Objects.The error message disappears if I change it back to Module but I would like to keep it class since the other parts of my code I changed to class and didn't return and error messages.
Class Atic
Sub Main()
Console.WriteLine("Hello, this proram will calcaulate the quadratic forumla ax^2 + bx + c")
Dim Quads As New Quads
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1 - Need to create a kind of composite property, like the font property, that it's showed with a plus sign to expand. For example i need to define a new pen, i need to define the color and the width... 2 - I need to define the color for one brush, but if i create a property of the type brush in the PropertyGrid it appears like "System.Drawing.SolidBrush"
View 2 RepliesUnder Visual Basic 2010, I am trying to define a specific instance of a static method that was created as a Java class. I have a vendor supplied dll added in as a reference.[code]...
But, I can't seem to define a specific instance of this method. Using "IntegrationMethod.getIntegrationMode()"always returns a value of zero.
There doesn't appear to be any way to "setIntegrationMode" to a specific value.
The documentatoin for this Class as provided by the vendor are shown below.
When I asked the vendor for assistance, their response was: "
Our javadocs for the IntegrationMethod class show that we provide three predefined instances of the IntegrationMethod class[code]...
I am having a problem with a and OOP class i made that contains a sub that creates random integers.
Problem is if i define two instances of this class and configure them(name in this case) then they both display different names but the random integers are ALWAY the same. in this case having the integers the same kinda kills the idea of the program.
Is it possible that the random part only every works for one class, but if .NET is fully OOP then this should not be possible... right?
Some of my Code (broken down to something smaller) i will display for obvious reasons.
Code:
how to display any image (by code)that scan it from twin scanner in picture box?
View 3 RepliesI define some global variables of a class as follows:
Private Class MyClass
Private var1 as Decimal
Private list1 as List(Of string)[code].....
But I found that after this form is closed, all above variables, var1, list1, list2 still exist in memory. I thought they should be collected by gc since the form is already disposed as I confirmed.
Add: I have monitored half an hour after the form is closed. But these variables are not collected by gc. I have an automatic update procedure on the form which uses above variables.Since the above variables still hold values, the automatic update procedure is always called which causes exception. (One quick fix is to check if form.isDisposed in update procedure. But I do not think this is elegeant. Besides, these variables occupy memory.)
This Image shows type-safe method of defining the Actionlinks ,how to define it in VB.NET
View 1 RepliesThis image shows how to define the RouteTable in C#, using the Route Class. How to define it in VB.NET?
View 1 RepliesI want to define several constants of pens like SystemPens. How do I do that?
View 6 RepliesI am using System.Reflection to load a type that I cannot otherwise load during design time. I need to pull all controls within a collection of this type, however, i the OfType command doesn't seem to like the reflection Syntax. here is "close to" what I got.
Dim ControlType As Type = System.Reflection.Assembly.GetAssembly( _
GetType(MyAssembly.MyControl)) _
.GetType("MyAssembly.MyUnexposedControl")
Dim Matches as List(Of Control) = MyBaseControl.Controls.OfType(Of ControlType)
So that code is bogus, it doesn't work, but you get the idea of what I am trying to do. So is there a way to use reflection and get all of the controls that are of that type?
i wonder if it's possible to define a variable/property of more than one type. Let's say i want a property TextWebControl that is a WebControl and also implements Web.UI.ITextControl(f.e. like a TextBox or Label). But i don't want to enforce that it is a TextBox or Label, but only one that inherits from WebControl and also implements ITextControl so that it also would work with controls added in future releases of .Net-Framework.
.Net-Framework 4.0
Edit: I have retagged the question and added VB.Net because it's my default language. Normally it's no problem for me to understand C# also, but i must admit that it's difficult to translate generic stuff to VB.Net without experiences and it's also better documentated in C# than in VB. So i would appreciate(and aceept) a working example of a VB.net generic type of ITextControl/WebControl.From Marc's answer i understand that i need a generic class. But how do i instantiate it in SomeClass? This won't compile:
Class SomeClass
Public Property info As InfoControl(Of WebControl, ITextControl)
End Class
Public Class InfoControl(Of T As {WebControl, ITextControl})
End Class
Is there any way to define a Generic in VB.NET which will accept only Singles or Doubles? I tried the following things, based on what I've found online, but none compile:
Dim target As Nullable(Of {Single, Double})
Dim target As Nullable(Of T As {Single, Double})
Dim target As Nullable(Of T {Single, Double})
Dim target As Nullable(Of Single, Double)
Dim target As Nullable(Of T As Single, Double)
I want to specify that target can either be a Single? or a Double? only.
I have a class called "heater". One of the properties is "designstatus", a string. I want to limit the property to one of three choices; "current", "obsolete", "notdesigned".
View 2 RepliesI want to know when I need to define a property in programming in general?,in every language
View 4 RepliesI have a list(of object) lets say ob1,ob2,ob3 that are classes I want to write a linq-querry that exstract from this list only one particolur object that is different time to time how can I write the linq querry?
dim List as new list(of Object)
list.add(ob1)
list.add(ob2)
list.add(ob3)
dim Result=(from P as ob3.gettype in list select p).tolist
but it does not work?
How to define array in vb2005? (Actually, I am making a game, whcih have to find out a pair of same pictures. I want to randomize 8 pictures, but it will randomize some pictures which is the same. Therefore, I need to use array.
View 3 Repliesbit is use for boolean where it is use to define result either 1 or 0 / true or false.
how to set it, if i want to define result either in or out/ yes or no/ big or small..
can i change it??what is the code to set it..
I know to define integer type sqlparameter but I do not know the decimal type sqlparameter for the precession.
I am giving a sample example.
//Code
Dim sqlparameters(2) as sqlparameter
sqlparameters(0)=new sqlparameter ("@RMID", SqlDbtype.integer,7)
but in case of decimal I am giving like this
sqlparameters(1)=new sqlparameter ("@RMID", SqlDbtype.decimal,7,2)
which is wrong
I have no idea as to how I can define a variable as "GLOBAL" in VB Express 2008. I used VB V 3.0 and if I remember correctly the statement "Global varName as Integer" allowed me to use the variable across different forms. I've tried the statement "Public varName as Integer = 0" on Form1 but Form2 tells me the variable is not declared.
The statement (in Form1) "Form2.Label1.Text = CStr(varName)" displays the value on Form2 in Label1 but I cannot then use the value again in Form2, e.g. "Label2.Text = Label1.Text". How I can transfer a variable value from one form to another and manipulate that variable in the second form?
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I have remplace the keyarr definition by my SQL query: With the code above, I can print both keyarr in a console. What should I change in the _sqlReader.Read() function in order to get keyarr definition like the first code. I would like that keyarr could be
interpreted by the rest of my code.
I need to define Virtual IP programmatically (Perl or VB or CMD or java).I need it for temporary use, I can't use any actual IP address and I don't care if it will be accessible only from local machine.
View 1 RepliesI'm using the Hashtable class for the first time, and have a question about it:Is it possible to define a type for all it's elements? So that when you for example only put strings in it, you can retrieve them without having to cast them from objects.
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