How To Create Accumulator For Collection Objects
Apr 23, 2012
I am trying to maintain a total for multiple collection objects in a class. When I create a new object, it resets the total to zero, only adding the current value being passed to the function. I have tried to use a static variable, create a second variable to hold the old total while adding the new value. The base class holds the total value, while the sub class creates the new object that holds information. I am passing the new value to a function in the base class adding the new value to the total when each new record is created.
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Oct 21, 2011
we have 3 classes:Class S, class A, class B / A and B inherits S.A has a property A1 and B has a property B1.we also have a collection of objects that has A and B objects.ex.
Dim c as Collection = new Collection
c.add(new A)
c.add(new B)
Now we want to make a general object that will read from the collection.
ex .
Dim obj as S
how can we cast obj in order to see properties A1 or B1 according to the class;
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Dec 28, 2011
suppose I have a collection of objects of different classes (like controls in a form), and all of their classes have a MyMethod extension method. How do I have the appropriatemethod be called for each object, depending on its type?or example,
For Each ctrl In Me.Controls
'call ctrl real type's MyMethod
Next
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Jan 25, 2011
i've researched and written a generic class (all my objects are the same structure) and i'm was just working on the collection using a hash table but i've just read a comment within (url...) in this forum...that we shouldn't use hashtables at all with vs2008.i actually need and object collection that contains other object collections within them.the application i'm trying to write is relatively simple (but i'm new to vb.net)it keeps track of the time for weight lifting training/workouts.a workout consists of 'say' a bench press, military press, curls, dead lift, etc within the "bench" you have 1,2, or 3 sets (how many times you do "the bench", within a set you have 1,2,3 or 4 lifters, each lifter does reps.then it starts over with military press..i guess i could base it on a treeview type structure (with parent child type relationships) but i usually think in terms of collections it appears that a collectionbase has no key and i'd have to keep track of them on my own...
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Nov 16, 2010
I'm trying to figure out the lifetime of the tmpTabPages in the following bit of code. Lets assume the form has an empty TabControl named MyTabControl, that there's a collection of strings called NameCollection.
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May 29, 2009
So I have a collection of Razzies created from a Collection of Bloops. I retrieve this collection using a Linq query. Reference:select-certain-properties-into-another-object for the query.I would like to know if it is possible to run a method on all of the newly created Razzies before returning the collection, or even right after, just without using a for-loop.
I tried ths:
Dim results = From item In bloops _
Select New Razzie() With _
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Nov 24, 2011
I'm implementing a customized Graph algorithm in vb.net, and I'm having the following problem:
Supose the code:
dim col as new collection
dim myC as new system.collections.genericList(of myClass)
dim obj1 as new myClass
dim obj2 as new myClass
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'In the next statement, the myC2 inside col collection will be decreased to contain 'only obj1, like myC. I supose this is for myC and myC2 contains only a pointer to 'objects obj1 and obj2 as well col contains pointers to myC and myC2 myC.remove(obj2)'The problem is that I have to only copy myC to myC2, like a ByVal argument in a function,'instead a ByRef argument, in order to mantain a copy of objects in myC2 while these 'objects should be removed from myC. How should I do it?
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Jan 29, 2009
Thought I had got this sorted earlier but unfortunately not. A property in a class is a collection of objects.
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Oct 4, 2010
I have a question. I have a class of Cars that I need to display in a simpli-ish string if they will be sold or not base on their number.
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I'd like to display a simple string like this:Cars to be sold: 1, 3-5, 7-8, 11, which is based of the .Sell value.Is there some kind of heuristic to create this kind of string in .NET or is it just a bunch of for/each and if/then and redimming of arrays?
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Mar 6, 2009
i have a sql query that can bring back a large number of rows via a DataReader. Just now I query the DB transform the result set into a List(of ) and data bind the Grid to the List.This can result occasionally in a timeout due to the size of Dataset. I currently have a three teir setup where by the UI is acting on the List of objects in the business layer.
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Nov 19, 2010
I have an object of type Dictionary(Of Int16, Polygon) and which contains sometimes up to 15 or so Polygons that i am creating bitmap files with the Polygon. This can take like 20 seconds sometimes so i was trying to pass the full Dictionary to background worker as an argument but i get an issue when trying to access each individual Polygon inside of the Dictionary because the Polygons still belong to the UI thread. How can I access the Polygons inside the Dictionary with the backgroundworker?
Dim worker As New BackgroundWorker
AddHandler worker.DoWork, AddressOf MeasurePolygons
AddHandler worker.RunWorkerCompleted, AddressOf WorkerCompleted
worker.RunWorkerAsync(PolygonCollection)
that is how im calling the thread. PolygonCollection is the Dictionary(Of Int16, Polygon) that contains all the polygons that i will be creating a bitmap file out of.
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Feb 28, 2012
I'm having problems doing a sort of a custom collection. The collection is Device Classes which is a collection of Device Class. My sort does not produce an error but the treeview control shows nothing. I am not sure what I am missing. I'm guessing just a simple sort won't work here but I don't know what I'm missing in my code. Here's the code that creates the collection
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Simply sorting the treeview will not work because it throws off the display of related info for a given device in listview controls. The collection itself needs to be sorted before the data is added to the treeview.
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Sep 16, 2010
I was just curious as to whether after you have added all of the Parameters to the SQL Command Parameters Collection. Is there a convenient way to iterate or loop through the Parameters and make Assignments to the SQL Command Parameters Values Property?
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Jan 24, 2012
I have a GUI which allows the user to select a report to view/edit. When the user selects a report, it shows the Items in the report. The Item has many properties - most of which are binding properly. One of the properties is Owner, and this is bound to a ComboBoxColumn.
Report
Items
Owner
I have done something very similar to this a few times and had no problems when I set the DataPropertyName, DataSource, ValueMember, and DisplayMember. The only difference is that this time instead of the Item type having an OwnderID it actually has an instance of the Owner object.giving the items bound in the list a self-referencing property that allows them to return themselves for the purposes of setting the ValueMember.However, When I bind it this way:
OwnerColumn.DataPropertyName = "Owner"
OwnerColumn.DataSource = ownersBindingSource1
OwnerColumn.ValueMember = "Self"
OwnerColumn.DisplayMember = "OwnerName"
I get a lot of errors like: Unable to cast object of type 'System.String' to type 'Owner'.
and:
The following exception occurred in the DataGridView:
System.ArgumentException: DataGridViewComboBoxCell value is not valid.To replace this default dialog please handle the DataError event.I was able to get around some of these errors by binding it like this:
OwnerColumn.DataPropertyName = "Owner"
OwnerColumn.DataSource = ownersBindingSource1
and also by making the ToString function on the Owner display the OwnerName property. This seems pretty hacky though - and I think I'm misunderstanding something fundamental as it still does not function properly.
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Nov 11, 2011
I have an error while using a collection that has been stumping me for years.I wrote a class to allow users to write equations in a txt file using RPN (stack based notation).The class runs through a select statement while reading the equation and then ends up with a final number as the answer. I have a collection to place these objects in for easy reference. For whatever reason I get random object reference not set to an instance of an object errors when there is nothing in the program that would remove objects from the collection, kill objects, or change the collection in any way. It is possible for one thread to call the calculate function while another thread calls the CurrentValue property. I'm not sure if this could be causing the error, but once it happens I get an error every time the program enters that code until I run out of memory.
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Jun 10, 2012
I need to Store Objects with Key like:
Key: <Fontname & FontSize> / Object: <Font Object>
Example content:
ArialRegular8 | <Corresponding Font Object>
ImpactItalic10 | <Corresponding Font Object>
TimesRomanRegular12 | <Corresponding Font Object>
These font types come from an external library, the real type is DocumentFont, I prefer not to store just values and recreate the font object later, so I need to store the object, and i want to be able to call Contains() later without looping. like for example Dictionary (of T Key, T Value), is this the best option? Also, to be able to call Contains(), i will have to overload function Contains() using an Interface or this is already built-in in some Collections / Dictionaries when using a String as Key?
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Apr 11, 2011
I created a custom class for a custom object. I instantiate like so[code]...
Now, I have two problems. First, right now this is just overwriting the same object properties, again, and again. I need to somehow dynamically name the object. Then, I need to place these objects in an array so I can iterate through them...
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Mar 19, 2012
I've got a multi-threaded app - that is using a global COLLECTION of objects.I'm starting to think that objects - when copied to objects - are really just reference pointers to the "single object" in memory - as they would be in JAVASCRIPT (too many languages At any rate - this code - when taking the object from the collection to work with is it making a new object to play with or is it working the single object that actually resides in the collection?
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Feb 26, 2009
We use a custom collection derived from CollectionBase to store our Business objects
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Jun 30, 2010
Okay I've been wondering about this for a while now, but whenever you assign variable values to objects they tend to just become references to the original object
For example:
Dim copiedCollection As ListBox.ObjectCollection = ListBox1.Items
For Each L As String In copiedCollection
If L = "Goodbye" Then ListBox1.Items.Remove(L)
Next
As soon as it encounters the string "Goodbye" and removes the item from the listbox, the program will throw an error saying the the collection (copiedCollection) has been modified. How can I make copiedCollection a true copy (not a reference) to the Listbox1.Items collection?
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Jan 24, 2010
I need two seperate lists, which every item is Integer, String, Bitmap - and one which every item is Integer, String String. However I don't know how to do this, or even where to look - I've googled for custom objects and custom object lists. What I'm trying to do is this.Custom Object1 is Integer, String, Bitmap Custom Object2 is Integer, String, String
In one thread I'll be adding items to List1(Of Object1), and processing them, and adding the results to List2(Of Object2), however I need to be able from other threads to look at the list and say only give me the items where Integer = (my thread ID), is this possible? Any help, or even links to information that would be relevant to this request would be helpful?
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Nov 16, 2011
code to use to add an accumulator so I can total up the items in my shopping cart?
Public Class MainForm
Private Property LabelText As String
Private Property ValueType As Integer
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Nov 7, 2009
This is for vb.net I've been working to develop a system which involves computation.What I've been trying to develop in my program is, I have a textbox where user will enter a numeric value,there is a button and a label below and in the first place the label should be set to zero. Everytime you enter a numeric value in the textbox and click the button it should add the value in the label and should save the value in the label so even if you exit the program whatever the last value displayed in the label should remain the same when run the program again,I believe it requires a database to save the value.Basically its like with payment system which saves the total amount of all payments made.
This is how should it works,say for example,if you will enter 1,2,3 it should save the sum value which is 6 in the label even if you close the program and when you run it again and enter another value it should add to the current value which is 6.
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Mar 23, 2010
I am having some trouble with my program that I am doing. I am supposed to code the application so that it creates a report which I have done. Now the problem that I am having is I have to use an accumulator for the total sales amount in the access file. I am stuck on how to have it say "Total Sales:" and then have the accumulator with the ammount of $32000 next to it becuase I have to use the accumulator to total the sales.
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Nov 30, 2010
I am currently going through Murachs Beggining .net programming book. I am trying toimplement an application for an exercise at the end of chapter 5. The applicationspecification is as follows.
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Jul 19, 2010
[code]The reason that this is a problem is that this is a collection of EventBase objects, but I'm trying to populate it with child classes instead. For example, I might have a JumpEvent class that inherits EventBase, and this is being put into the EventBaseCollection. That means that value.GetType() returns the type of JumpEvent, which as you might guess does not equal the type of EventBase.The goal of course is to simply loop through all of the various events without having to know anything about the sub-classes. Is there a way to determine the type of the base class so that the OnValidate call will work? Or is this just the wrong way to go about it altogether?
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Dec 29, 2010
If I have a large number of classes, each similar to the other in certain aspects (they all share a common base class, but each does things differently), and I need to create Windows forms for each to allow easy changing of their values through a GUI? Create one matching form for each object in VS' forms designer, Or Use code to create the forms dynamically at runtime.
#2 makes the most sense to me, because a lot of these objects will share very common features of the form, notably "Ok" and "Cancel" buttons. But one object might need to draw a textbox on the form while another might need to draw a combobox. Not to mention, if I want to put icons on the "Ok" and "Cancel" buttons, I'd have to do this for each copy of the form in designer, and that sounds like it could get out of hand quickly.But is drawing forms through code sane? VS' forms designer is pretty sophisticated and designed to make life easier. Am I wise to consider ignoring its functionality and diving into the trench warfare of forms design through code? Or are there examples of automating form creation based on an existing object's properties?
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Apr 13, 2012
OK, so my accumulator is now adding and showing properly in the form as a total. However, something is wrong in my if... then statement and it's not throwing it to the 2nd level after reaching the 125.*Edit to show updated with the Do While Loop. Now causing issues with my input error msgbox... *
do while decTotalCredits < 125
If IsNumeric(txtCredit.Text) Then
' This statement will convert the string entered to decimal and establish the
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Nov 16, 2011
the code to use to add an accumulator so I can total up the items in my shopping cart?
[Code]...
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Apr 25, 2010
Okay my assignment is to change a code up using two functions instead of a subprocedure to calculate total rainfall and avedrage rainfall and then to add a startover button to the application which not only clears all the labels but also clears the counter and accumulator. This is what I have gotten so far my functions do not work and I can get the labels cleared. I just can't get the counter and accumulator to reset back to zero
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