Populating Dictionary - Creating Objects Within Loop?
May 16, 2010
I am trying to populate a dictionary with objects created from data in a recordset, but am having difficulty with VB's object referencing. I am very new to VB. Pseudo code of what I am trying to do:
dim dict as Dictionary
rs = getRecordSet
while rs.moveNext
set myObj = new MyClass
myObj.properties = rs.relevantFields
dict.add myObj.getUniqueKey, myObj
wend
However, all 'objects' in the dictionary are actually references to the most recently created (and thus last) object in the dictionary. I know why what I am doing above is not working, but I don't know the correct way to do it so that each element in the dictionary is it's own object.
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Aug 31, 2011
I don't know if this is doable, maybe with Linq, but I have a List(Of MyType):
Public Class MyType
Property key As Char
Property description As String
End Class
And I want to create a Dictionary(Of Char, MyType) using the key field as the dictionary keys and the values in the List as the dictionary values, with something like:
New Dictionary(Of Char, MyType)(??)
Even if this is doable, internally it will loop through all the List items, I guess?
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Jul 20, 2011
Recently started working with VB.NET, and I'm just playing around with the controls and everything. What I want to do, is populate a drop-down list or a combobox (on program load) with data from a dictionary. I'm used to php, so I tried a for each dictionary.items as newitem combobox.items.add(newitem) but I can't get it working. Can someone give me an example of this? And what if i wanted only the key to show in the drop-down, and the corresponding value shown on a label besides it when I make a selection?
[Code]...
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Jan 29, 2011
I have a program like this.
Module Module1
Public Class Mstr
Public Property Prop1 As String
Public Property Prop2 As String[code]....
But it is not working as I expect it to. You can see it from.The DtlsB properties of all three DtlsA objects are having values from last iteration.
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May 12, 2011
I add objects (structure type) to a dictionary with string keys.
i don't figure out how to update a value of a object.
i use TryGetValue to get a reference to a object of the dictionary collection.
But the changes i made at the referenced object are not made at the object at the dictionary.
Any hints how to get a object reference to change values without to re-add the complete object?[code]...
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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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Jun 5, 2012
I'm having trouble implementing an IComparer method. Essentially, I want to compare the properties of two custom objects (the properties are of type integer).dE is a Dictionary(Of String, customObj)prTabIndex is a property of customObj and is of type Integer (these hold true for all examples)After some more searching I found this thread which suggested 3 things: a List approach, utilizing LINQ, and using some C# 3.0 features. I've tried three different ways:...rolling my own IComparer implementation:
Public m As Sub(ByRef d As Dictionary(of String, customObj))
Dim sortedD As New SortedDictionary(Of String, customObj)(d, myCompare)
End Sub
[code]....
Note that VS2008 has underlined 'dE.ToDictionary...' (to the end of the line) and giving me two messages depending on where I hover my mouse:
1) "Data type(s) of the type parameter(s) in extension method 'signature' As 'signature defined in 'System.Linq.Enumerable cannot be inferred from these arguments. Specifying the data types explicitly might correct this error. Seen while hovering over "ToDictionary".
2) Nested function does not have the same signature as delegate 'signature'. Seen while hovering over anything after "ToDictionary".
Q1) How far off am I in each of the implementations?
Q2) Which one is the computationally least expensive? Why?
Q3) Which one is the computationally most expensive? Why?
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Jun 17, 2010
I'm looping through a zip file trying to add the file name of each file within.Is this the correct method?
Dim ZipNameArray(?)
Using zip As ZipFile = ZipFile.Read(ZipToUnpack)
For Each file In zip
[code].....
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Jul 29, 2011
Currently I'm trying to fill a 3x3 square with random x's and o's to make a tic tac toegame. Unfortunately the game doesn't seem to output all the x's and o's. Logically, from what I can see, it should be able to but it's not.
Shared Sub twodimension()
Dim tic(2, 2) As String
Dim min As Integer
[code].....
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Aug 30, 2010
I want to use a Dictionary(Of Key, Value), and the Key is not a base type, but a class like:
Public Class MyKey
Sub New(ByVal packet As String, ByVal sent As Boolean)
Me.packet = packet.ToUpper.Trim
Me.sent = sent
[code]....
But to have consistent results I have also to implement Object.Equals and Object.GetHashCode:
Public Class MyKey
Implements System.IEquatable(Of MyKey)
Sub New(ByVal packet As String, ByVal sent As Boolean)
[code]....
is that GetHashCode implementation correct? How should I implement it, to return a hashcode that kind of merges the string and the boolean hash codes?
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Feb 25, 2011
I have created a script in powershell that has done this, but amo moving to a VB app and am having troubles.The snippet that I am adding shows what I did in powershell. I created variables using the XML and from a SQL database compared them, and updated the XML to reflect changes pulled from the database. I want to cycle through creating the variables as more may be added in time and want to make sure I don't have to keep adding code to pull out the data manually one node at a time.rudimentary code as I am new to both powershell and VB. Currently using VS2008.
code/xml below.
$xml = New-Object XML
$xml.load("g: estingackup_local_config.xml")[code].....
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Nov 23, 2010
How to avoid for loop (Dictionary Array) using LINQ
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Oct 24, 2009
I'd like to create a Dictionary that is indexed by Strings: Dictionary(of String, ...). I'd like the Type after the comma to be an Array of MyObject's. If all I do is the following:
Dim D as new Dictionary(of String, Array)
I feel like I'm missing out on some performance very time I access a member:
Dim Object1 as MyObject = MyDictionary("Key1")(4)
Doesn't it have to perform some type of lookup to figure out what type of object the array is holding every time I access it in this manner?
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Oct 8, 2009
I am building a form that will eventually list a group of functions on the left. If you drag a function onto the form, it will create a listbox and a label at the loction you dropped it to. If you drag a function into a listbox, it will add that function as a listbox item. I have this working kind of. The problem is that once I create a new listbox, I am no longer able to add items to the previous ones. Here is my code:
Public Class Form1
Private MouseIsDown As Boolean = False
'rivate Functionlist As ListBox
[code]....
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Jan 25, 2011
Before any jumps in and says, Why dont you just use a gridview, i have my reasons not to use it.I trying to dynamically create a table and then populate the cells via a linq object.
Good news, i can dynamically create the table and the cells.
Dim numrows As Integer = MyActions.Count()
Dim numcells As Integer = 5
[code].....
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Sep 5, 2011
As I wrote in topic.I'm using DirectoryServices to connect to remote AD
When I write Collection.Count it prints for me for example 198 - co it's good.But when I want to loop through this collection ('for each' or 'for') application shows error that counter should not be greater than collection or below 0.
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Jan 5, 2012
I have a loop with WebRequest objects which I declare every iteration. I thought it would be more efficient to declare them outside of the loop and only modify the one parameter that changed but it didn�t work. Why is that? It seems like the loop acts like a subroutine or other block that kills it�s objects at the end of each iteration. Is this the case? It seems other global objects like a text box can be modified this way so why not the WebRequest?
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Jun 17, 2011
threads that watch folders and process files. This works fine, but every time needs change to add a new folder or just change some existing rules I have to go in and change the program. I want to builda front end that storesprocessing infofor each watchfolder. The program would then read the configs and build the threads based on them. I cannot find a way to loop through creating the threads.
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Oct 5, 2010
I'm using VB.net from the Visual Studio 2008. I have a large number of PictureBoxs in a form. They have been created sequentially, Pic1, Pic2, Pic3, ... Depending on how I access this form, I want to turn off a number of them. I'm working with the code below.I can put the name of the object into a variable, Pic, but am still unable to hide the object names in that variable, Pic.Hide().
Dim StartNumber As UShort = 1
Dim StopNumber As UShort = 33
Dim Number As Object = 1
[code].....
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Apr 10, 2011
1) Add a Private variable named _area2) Associate the _area variable with a Property procedure called Area3) Change the CalculateArea method to a Sub procedure. The method should calculate the area and then assign the result to the _area variable.4) Include a parameterized constructor in the class. The constructor should accept one argument: the side measurement. After using the Public property to initialize the Private variable, the constructor should automatically call the CalculateArea method.At this point I believe I've completed the first 2 steps for the Square method, but I'm not sure where to go from therHere is my code for the Square class and the Main Form, in tha order:
Public Class Square
Private _side As Integer
Private _area As Integer
[code].....
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Nov 18, 2009
1. Write a Visual Basic Console Application which creates two DateTime objects. One DateTime object should be used to store a value for date purchased. The second DateTime object should be used to store a value for date paid. See below for more information.
2. Assign values to the two DateTime objects.
3. Use the toString method to display the two DateTime objects.
4. Compare the two dates to determine which date occurred first.
5. Compute the number of days elapsed between the two dates.
6. If the date purchased occurred before the date paid, display: The number of days required to receive payment was ________. Replace the _________ with the number of days computed between the two dates.
On the other hand, if the date paid occurred before the date purchased, display: The number of days this order was pre-paid was _______. Replace the _________ with the number of days computed between the two dates.
If the two dates are identical, display: The payment was received on the same date as the purchase.
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Jul 25, 2011
I'm having a problem at the moment developing my application. What i need to do is find out how many modems they are connected to my system and send data to each one in turn. I have the programme working for one modem at the moment.
So I can send data to a modem that i specify, for example a modem on COM port 1. I have functions already that will give me a list of COM ports that I need to open.My problem is that i want to dynamically create a new modem object along side existing modems and store them in a collection.
[Code]...
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Aug 27, 2010
I'm wondering on how you would go abouts instantiating a class that contains other complex objects. for example an Payment Class which has Date,Time, etc.. and it also holds a reference to a paymethod object which has id,Type,Description etc.. How do you instantiate the payment class with all the other objects without one or the other failing, how do you create the payment class which doesn
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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.
[Code]...
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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Jun 9, 2011
I have decided I would start small and make a program that would create a "receipt" list in a listbox and a total. Now, I would like the user to be able to add their own "menu" items. I'm assuming the best way to go about this would be to have them actually add it to a database and then a function in the program will refresh the dataset with the new list. However, this is where my problem lies. How can I tell VB .net 2010 that I want to create a new button (or buttons) on the fly, in an orderly pattern on the form, based on the input from a DB?
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Mar 17, 2009
I would like to dynamically create an object (in my case a thread) and then be able reference that object. Simplistically put, I would like to read from a text file and then process each item using a thread (so that I don't have to wait for each item before starting the next). The problem is that I cannot think of a way to create a new thread dynamically ie. thread name so that I can then wait for all created threads before doing something else.
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Mar 28, 2009
Is there a way to dynamically create an object at runtime?Background: Basically i have an employee class that i want to instantiate every time an employee logs in. What i don't want it to have an employee object already created for every employee, but when they log in the object gets created.
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Dec 16, 2011
I have a MySQL database with a table called "Locations" which looks a bit like this
id | name | other parameters
1 | shop1 | blah
2 | shop2 | blah
[Code]....
This works, but it is inefficient calling the database through the loop, how do I avoid this?
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Dec 16, 2011
Im considering making my own command line interface with custom commands etc. I was thinking the following objects would be sufficient:
Textbox - for input
Rich text box - for showing processes and output
Button - to insert input
If it can be done, how can I provide line breaks in the output on the rich textbox e.g.
line1: input instruction
Line2: <cp><textfile.txt>
Line3: I/O error, file not found, check file root.
My version of CLI will have no integration with the windows CMD.
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Dec 26, 2010
I have a Clients master object and then a number of child objects whose exact number is not known in advance such as Client-Contacts, Client-Payments etc, all of which have a one-to-many relationship with the Client master object.How do I define classes for such a scenario? Do I for instance create the master Clients class and can then I create an array of class somehow for child objects?
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