Object Oreinted Random Failure - Define Two Instances Of Class And Configure ?
Oct 27, 2009
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.
I was create Access database with Access 2003. I create VB project with Visual Studio 2005 Standard With connection wizzard I create coonect with this Access database, select all tablesI see this database inside Data sources and inside Server explorer Test connection is OK When I drag and drop table from Data sources, Wizzard don't create DataGridView, DataSourceBinding etc .. and I see popup window with mesage: Object reference not set to an instance of an object and then "game over"
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).
I have created a class for a Sports Facility. A facility has a Name, Status, Notes, etc as members of the class. This works well, I can create a new instance of an exisitng Sports Facility from the database, create a new instance, etc. All working well.What I am stuck on is accessing a list of Sports Facilities. I know I can create a new list by doing
Dim List As New List(Of Facility)
For Each fRow As DataRow In ds.Tables("Facilities").Rows
The class Random is out right defective. It always produces the same random numbers in the same sequence. Things I have tried so far is every kind of seed you can think of as well as Randomize. The result is that I always get the same random numbers in exactly the same sequence.
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
I am trying to figure out how to use variables to define which object to update. I could of course use a case statement to pick the object based on a variable, but it seems to me like there should be a more direct way. Here is a smaller example of what I would like to do.In my form I have 4 picture boxes (pbox1, pbox2, pbox3, and pbox4). I then want to change the image in one of the boxes, but the box I want to change will be determined by a variable (say maybe a randomly generated number). Is there some way to dynamically concatenate the "pbox" with the number that VB would understand it and use it as an object?In this example I could easily build a case statement to handle the selection, but in my real program there will be many more than 4 options.
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:
I've created a private sub which enables me to move to the next object when I press enter in the textbox or any input controls... What I want to do is to create a universal sub procedure for moving to next object. this is my code
In the following code as you see I am defining myFile inside the timer sub; which of course is not a good idea. The FilePath is derived in form load before the timer kicks in. How can I declare myFile globally so it can be used in timer sub as well as in form load?
Private Sub tmrInterval_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tmrInterval.Tick Dim myFile As New IO.FileInfo(FilePath) If myFile.Exists Then ... ...
I want something like this:
Public Class Form1 private myFile As New IO.FileInfo()
'but I do not have strMessageFilePath value yet, that will be achieved in form load.
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'm trying to create 3 instances of the the Workshop selector form for the 3 individuals that I have inthe listbox to appear when I first run the program.
dim object1 as new clsDatadim object2 as object object2 = getobject("object1") "getobject" function is my "needed function"
the purpose is to set object2 to have same memory address with object1 so if i change the properties of object2 then the properties of object1 also changes..
I have the following problem. (VB.Net 2008)I have created a class (myFirstClass). In this class there are a lot of calculations being made wich gets fired by events in that same class.Now i want that same class to be able to fire more instances of itself. However i noticed that each time i fire an event from a Sub the program waits till the event is finished before going to the next line of code. This is a problem since i want the event wich fires a new instance of the class to fire it and forget about it.
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
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"
this is probably something I should know, but I'm puzzled by this.I'm trying to create some objects and being able to access and modify these globally. I tried to create a Public Module and declare a few objects in this.I am able to access these from another sub, but I get an exception error when after building and runing the process and trying to modify these object. The same thing happens if I declare the object in the Public Class Form1. For example like this:
Public Class Form1 Public appWord = New Microsoft.Office.Interop.Word.Application Public wordDoc as Microsoft.Office.Interop.Word.Document
Is there some interface I can implement to allow basic comparisons and math to happen as it would an integer?
For example, let's say I have the following class:
Public Class Something Public SomeBigNumber as UInt64 End Class
I would like to do something like this:
Dim SomethingA, SomethingB, SomethingC as New Something .... If (SomethingA-SomethingB) > SomethingC Then 'Do stuff End If
I was hoping to be able to implement some interface (if that is even the right term for it) that would return the UInt64 contained in the class for comparison and math, if possible.
I have a form whose purpose is to let the user to load map files.The form may manage a variable classes of maps, and each class have his own UserControl.To make it more user friendly, I added to each UserControl (different instances of the same class), a little map, showing a small picture of the map, and some data, as bound coordinates.
The problem is, that it looks really ugly. The maps are so big, compared with the rest of the UserControl (who contains just a button and a textbox to search for files).I wish to fix it, but I din not see an elegant way to include the pictures and info.I attach a form screen capture with two UserControl.I would like to get some tips for more experienced users. There are some guidelines?
info on creating instances of my own class at runtime. Simple project for family recipes but would like the option to add new recipes with new instances of my own food Item class at runtime. Creating my own class,no problem. Storing the data in an XML file, OK on that as well. My issue is creating new instances of different food item class as I use this program over time
I have a sub that runs on a button click which I want to create a new instance of a custom class and add it to a list of already created instances of this class. I want the result to be a List Of collection of all of my class instances.
My problem is that each time I run the sub, it simply 'overwrites' the first instance of the class and adds a copy of it to the list instead of writing a new instance. My code is along these lines
dim objFixture as new clsFixture For n As Integer = 1 To intNoOfChannels objFixture.SetChannelAddress(n, intCurrentChannelTotal + 1) intCurrentChannelTotal += 1 next lstFixtures.Add(objFixture)
I created a program a while back, in the traditional VB.NET way by drawing a bunch of forms. I have started playing around with creating the forms at runtime using classes. I have a placeholder form called frmStartup which merely calls the CreateLogin() sub from the CreateFormClass. The CreateLogin() sub creates a new blank form, then calls the grpbxLogin(), btnSave() and btnExit() subs from the FormElementClass which adds all the buttons and textboxes to the form. Within the FormElementClass, I have associated btnSave and btnExit with event handlers. These even handlers call subs from the DataProcessingClass. The event handler for Exit works just fine.I am having a problem with the Save event handler. Precisely, I don't know how to pass either the username or password from the Login form to the btnLogin_Click() sub in the DataProcessingForm. I have tried using Me. and frmLogin., but the program doesn't see either of those. If the Login form is an instance that is disposed of once another Sub is called, then it won't exist later on to call from. I have tried declaring variables and passing those along to btnLogin_Click, but no matter where I put it, the program doesn't see txtbxUsername.Text or txtbxPassword.Text. Not even from within FormElementsClass, which is were the boxes are created.Any ideas on how to pass variables in this case? I am not even sure what you would call this such as passing between classes, or passing between instances.[code]
I've decided to forget the d@mned custom code because everything I do with comes up with errors I don't know how to fix and it seems no one else does either. Or they do and they're keeping to themselves.
I put the functions that I needed to use in a class called MsgBoxOperations. The file name is MsgBoxOperations.vb In the report, up on the standard bar where file, edit, view, and all the other stuff is, is one that says report. You click that and go to report properties and it brings up where you can name the report and put in custom code...(hate custom code right now...) and where you can put references and class instances. Clicking on the Reference tab brings up wher you put in your references and classes.
In the classes area it asks for the Class Name, which I put in MsgBoxOperations, and the instance name of that class, this case mbo. I get that far and put in those two things and save it. Then I go to the textboxes where the values need to be. I put in the text box: =Code.mbo.GetStartDate
I've already tried taking the Code. part out and it screams that mbo isn't declared. So it does have to be there. I go to run the code and comes up with this error: QuoteError in class instance declaration for class MsgBoxOperations: [BC30002] Type 'MsgBoxOperations' is not defined.
I've posted before and still have received no help or someone tried to help but then stopped when their suggestion failed and then no one else wanted to help. I've googled this problem to the point where every link that it comes up with I have already clicked and found their information useless. I've got a freaking migraine because of this issue and have been in tears over it more than once.
I am just getting started with VB.NET - what I couldn't find in my book is whether a new instance of an object with the same variable-name will delete the previously stored values - or will that somehow remain in memory?This is the scenario:
I open a data file and load the contents in 'Dim var As New dataObject'what happens when I again open another file and the same line is encountered:Dim var As New dataObject'
Hope the question is clear p.s. the dataObject is a simple structure with a bunch of variables in it - nothing fancy.
