Updating String Property In A Class?
Jun 2, 2012
I have created a new class with a string property called "Text".
The property will hold a sentence typed by the user.
I use "KeyPress" event to get the character pressed and use "Console.Text = Console.Text & e.KeyChar" to update the property. Where console is an instance of the class.
The problem is when I press "Delete" nothing happen.
That's the code within the event scope
MsgBox(Asc(e.KeyChar))
Console.Text = Console.Text & e.KeyChar
MsgBox(Console.Text)
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Oct 1, 2011
I am trying to use several Class arrays to hold values that I will cycle through at a later point to perform some calculations. I need to change the array sizes to fit the data as it is entered. I am using one procedure to set the first element of each array and then a separate procedure to pass the additional values as they are entered.
Until my last attempt at changing my code, my StartBalance sub seemed to work, I could step through and see the values assigned to the class arrays in the code block. However, when it moved on to the Transaction sub, it did not recognize that the first set of values were set, the array shows zero values for index 1.
I have gone through several changes trying different ideas from reading blogs and articles, but I guess I am not understanding how these work. I even used the class arrays directly instead of the Property procedures to see if I would get a different result, but I do not.
I believe I must be approaching this incorrectly and though I can find dozens of examples of setting class variables and even a couple on using arrays as class variable, I can not find any that show how to then pass values to those arrays.
Public Class Statement
Private _tranDate(1) As Date
Private _amount(1) As Double
[Code]....
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Nov 16, 2010
I have a function that updates a Client in the database. A client object is passed in, along with a string array of fields/properties that should be updated. I need a way of accessing each property in the client object, based on what is in the array. Basically, I am looking for the VB .NET equivalent to this javascript:
var fields = ["Firstname","Lastname","DOB"];
for(field in fields)
{
[code]....
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Nov 3, 2009
I have created a class that contains a property array, but I cant use the setters and getters.
[Code]...
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Jan 5, 2010
I am trying to create a property of type string array (if this is possible).....and I seem to be lost.
I tried the following, but it says "String cannot be converted to '1-dimensional array of string'" at the return
Private _strZipList As String()
Public Property strZipList(ByVal i As Integer) As String()
Get
[Code].....
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Jun 1, 2012
I have a very simple class that holds a few public properties - ID, Text, Colour, etc. and a Boolean called 'SelectedItem'. Just like the Checked property on RadioButtons, only one item can have its SelectedItem property set to True within a particular group. Note: there will be several separate groups (lists), each allowed to have only one item with SelectedItem = True.
My first thought was that I would probably just have to handle everything outside of the class, setting SelectedItem to False for every other item in a particular list when another item was selected. But that seems rather inelegant to me. So I've been trying to think of how this might be done within the class. For example: could I perhaps have a private string property called say "GroupName" - set in the New sub when adding a new instance of the class - and then use a private shared method to set every item's SelectedItem property to False, provided the item has the same GroupName as the newly selected item? I would have a go at doing this but I have no idea how to enumerate every instance of a class from within that class, or whether that's even possible. Is it? Or is there another (better) way to achieve my goal? Here is a cut-down version of what I've got so far:
Public Class ResourceItem
Public ID As Integer
Public Text As String[code]....
As can be seen: instead of instantiating a new ResourceItem and passing that as an argument to the manager's Add procedure, I'm simply passing the details of the new item and the procedure is creating the item from those. I don't know whether this is a good or bad idea - please advise - but I've done it because I couldn't figure out how to make the SelectedItem property only writeable by the manager, so I wanted to avoid having directly accessible objects that could have their SelectedItem property set to True without it deselecting all the other items in the same group. Of course that still leaves the possibility of setting a variable to one of the manager's list items and setting it from there, so I would still like to know how I could prevent that, if possible.
UPDATE: I didn't use the code above in the end, deciding instead to go with Cyborgx37's solution - which seems to work perfectly well for me despite the warnings about best practice. I also realised I would need to use the same class in another scenario where multiple items could be selected, so it was easy to add a Boolean property to the manager to enable that.
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Aug 13, 2009
I have the following code:
Public Class MyColorsClass
'Constructors
Public Sub New()
'Empty Constructor
[code]....
However, if the empty constructor was called to instatiate this class then the colortype is not yet set. Therefore, if one accesses the 'IsColorCool' property it will always return 'False'. Now for the sake of this example, I must keep the empty constructor as part of the class.Now I could add some code in the 'IsPropertyCool' to check and see if a ColorType has been defined, and throw an exception if it has not been set, but I don't really want to do that.I also could always move the logic OUT of the property and into a method on the class called 'DefineIfColorIsCool' or something, and make the owness on the caller to make sure the method was called if they want to use the property 'IsColorCool'?
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Apr 7, 2011
Supose a base class
Public Class airplane
Private var_num_seats As Integer
Private var_num_engines As Integer
[code]....
Obviously, I don't wish that the class Glider has the method "start_engines" neither the property "num_engines". Otherwise, other child classes may have. How can I supress these property and method in child class, not just ignoring (if I can)?
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Sep 29, 2011
I have procedure (Import) that calls a for a new instance of frmImportData. I also have a class name clsBatch that has a data table property called prpParametersTable.For some reason, I get an error (indicated below with ERROR>>>) when trying to assign prpParameterTable to cv_dtImport2. The error states "Object reference not set to an instance of an object.". Why does this error not happen when I assign dtBP to cv_dtImport1? Both cv_dtImport1 and cv_dtImport2 are equal to Nothing and in my Import procedure dtBP = prpParametersTable.
Public Sub Import(ByVal clsB As clsBatch)
Try
Me.cv_clsB = clsB
[code]....
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Nov 14, 2009
I have three class files, accounts.vb and transactions.vb in addition to my form.vb. I am unable to retrieve a member variable from on class from inside the other. When the combobox index changes, the program loads the correct account (checking or saving) from two different sequential files. I don't think I have the calcBalance procedure in the correct class file. And that is what I am having trouble with. Accessing it to display it. [Code]
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Mar 30, 2010
This is a bit of a continuation from a previous post for which AtmaWeapon was very informative.
Problem:
A parent class has a sub class with various properties. A property of the parent class is a List(of T) with T = the sub class The issue is how to store data in the sub class of the instantiated parent
Some example code (hopefully formatted correctly):
Code:
'=========== Class Definitions =============
Public Class courseClass
Public Class timeTableClass
[Code].....
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Apr 2, 2010
I'm looking for a tutorial on how to Adding a list(of Class) or Collection as another Class's Property.What I am after is something like the Columns Collection for the DatagridView control.I would like to add Items in the graphics screen. Where the item list is displayed in the left panel and the selected Item properties are displayed in the right panel.
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Apr 19, 2010
I have a windows form which contains a textbox.I have a loop in my code doing some farly intensive work. In the middle of the loop I want to update my text box.text property on the form to let my users see some simple progress.
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Apr 7, 2012
I have a class that has the following property that is generated by the methods in the constructor.
Public Class clsLoadTables
Private _ds As New DataSet
Public Property ds() As DataSet
Get
[CODE]........................
My problem is that I do not want to inherit this class, but I have other classes that need to access the ds DataSet property. If at all possible I would like to not use inheritance and not load my datatable more than once in the program.
Here is my failed attempt to access the property inside another class that is not inheriting clsLoadTables:
[CODE].........................
How I can access this dataset that I want to load only once in the program from many classes without using class inheritance or a global module?
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Jul 29, 2010
I know that an interface can contain another interface within it.But;can a class contain another class within it?Can an interface contain another interface within it?
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Jun 17, 2009
Using Office automation in Word 2007, I view the Document Information Panel, showing me properties of a document that resides in a SharePoint location. Using VS 2008, I interrogate the following in the Immediate Window:
[code]...
but I don't see a corresponding change to the screen. I do however see that, on Advanced Properties/Custom Tab that a Custom Property by the name of "Process Name" has been recorded with the value "New Value"There seems to be some kind of one way mapping going on between "server" and "custom" properties, but the really strange part is:I can update SOME server properties, others I cannot.I don't know a darn thing about SharePoint, other than as a dumb user. And getting any help from a SharePoint admin in my company is probably a very long shot...I checked all of Word's Built-in Properties and Custom Properties, I decided that none of them can be used to update the "Process Name" "server" property.How can I update this stubborn property? Most of the server properties I can update, a few I cannot.I see some articles referring to using what looks like "SharePoint objects." Do I need to download an SDK just to populate these properties? So far I've used Office automation, because I am running locally on the user's PC and pre-filling documents using the Word object model. All that is left is to finish populating the last couple of server properties after I copied the doc to a Sharepoint folder.
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Jul 28, 2010
I have two classes, and for a property in one of the classes I'd like to be able to load it up with an array of the other class. However my attempt at accomplishing this results in a "Object reference not set to an instance of an object" error. I know it's a rookie mistake, but I'm stumpedssist?
My code is as follows:
Namespace Parking
Public Class garage
[code]......
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Jul 5, 2010
bare with me during this silly example. :-) Let's say I have a class like this:
Public Class Animal
Public iLegs as int32 ' Number of legs
Public bWings as Boolean ' Wings? Yes/No
End Class
And another class that inherits the "Animal" class and adds one more property:
Public Class ScaryAnimal
Inherits Animal
Public iScariness as int32 ' 0-100, how scary is it?
End Class
Now, if I have an instance of "Animal" with some values in it, and I decide I want to cast it to a ScaryAnimal for some reason, how do I do that without having to create a new instance of "ScaryAnimal" and copy each property value?Basically I'm looking for a way to do this, without having to write the lines marked with '*** below:
[Code]...
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Feb 17, 2010
I have a vb.net class with properties defined as follows:
Private m_Property1 As String
Public Property Property1() As String
Get
[Code].....
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May 5, 2012
I have a class in vb.net defined as public class A
class A is created on Load and gets called once per program loop
The constructor for class A includes the argument (byref Value as long)
I have a global variable called varB that is passed to class A on creation.
now why when varB is altered during the program loop, the change is not reflected within the class?
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Nov 2, 2011
I've been programming in vb.NET for a whileAnd to be honest, its turning out to be a real pain.Here is the
Form1.vb: Imports System.Threading
Public Class Form1
Dim trd As Thread[code].....
So, I have a form (form1) with a label on, this label simply reports the status of the thread.The thread begins the Class1.Main() sub, and I have a delegate setup to change the text propoerty of the label.Now,I know the label is created on the UI thread,so I assumed the delegate would work. However,it seems that it updates the .text property, but doesnt redraw the control when .Update() is called .What am I doing wrong?I have found lots of examples of delegates, but all run from within the same class. I want to use threads too, not a backgroundworker! This code is a "simplified" version of a project I am on, which is encountering the same problems
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Dec 15, 2010
I'm trying to update the UI from a background thread without invoking the control. Mainly because I've tried to do so and it never worked from a class. It worked just fine within the form class, but froze up in the class. I didn't receive any errors, it just lost its multi-threaded-ness.
I'm having a similar problem with using the SynchronizationContext class. I made a quick example to test if this would work how I think it should:
[Code]....
There's very little information on MSDN about this class in general and every example on the web I've seen so far, has nothing to do with classes.
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May 19, 2010
I have got problem when using the SQLCommandBuilder class. For me it throws an error saying that the select statement does not return any primary columns.... Which is weird becouse i am sure it does since the select statement is "SELECT * FROM MyTable" I am prety sure that selects everything including the primary column which is set to primary , realy i checked and doublechecked.
Secondly i tried to manually set the column(0) as primary by setting it's property bu no such luck of making it work.
I have these two functions in a class that i instanciate an object from in the main program:
Code:
Public Function GetDB(ByVal DBName As String) As Data.DataSetDim SQLAdapter As SqlClient.SqlDataAdapter = Nothing
Try_SQLdataSet = Nothing
[CODE]...
This Functtion fills the dataset and returns it to my main program where i do lovely stuff with it. (Just as a side note this is a SCADA system and i always need the entire DB which is never bigger then just a few ( 6 ) entries so i must go for "*" ^^). Good part is, this works like a charm, i love it. Now i need to reset a few status bits etc and i assume with the update command. And that is where my joy starts to get stomped on a bit.... The code:
Code:
Public Function SetDB(ByVal dataTable As Data.DataSet, ByVal DBName As String) As BooleanDim SQLAdapter As SqlClient.SqlDataAdapter = Nothing
Dim SQLCommandBuilder As SqlClient.SqlCommandBuilder
[CODE]...
Now this would have been a great and small sollution to updating datasets with the server but obviously it doesn't work. There is that pesky error about my table having no primary key and I know it's lying it just want to annoy me :P. But seriously I am puzzeld why that error wont go away and i have exhausted all the tutorials i can find on this.
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Sep 24, 2010
I'm having an issue where my main form isn't updating even though I see the event fire off. Let me explain the situation and share some of my code which I'm sure will be horrible since I'm an amateur. I created a class to take in the settings for running a process in the background. I add some custom events in that class so I could use that in my form instead of a timer.
[Code]...
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Oct 5, 2010
class
eg: dim classobj = xyz("CLASS_NAME") ' where classname is a valid class name
and dynamically raising a known method of that class on that newly created object or class reference.
[code].....
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Jun 15, 2010
I am running from a problem while iterating over class properties.
I have my first class:
class Item
private _UIN as integer = 0
private _Name as string = ""
[Code]....
I get UIN, Name, ItemCategory but i expected UIN, Name and Category.
I am a bit unclear about this and dun know why this is happening? What should i do to correct it?
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May 26, 2010
I have 2 classes and I set a property in class A... how can I get this value within Class B?[code]...
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Jun 25, 2011
How can I get a string with the name of a property at run time?Obviously using GetProperty, as shown below, is NOT a solution since it requires knowing the property name to begin with:
Imports System.Reflection
Module Module1
Public Class Country
Public Property Capital As String
Public Property Population As Long
[Code]...
What I want is to get the name from an instance (Nation.Capital for example) or from the type (Country.Capital).
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Aug 27, 2011
Private _Order As Order() Public Property Order() As Order() Get Return _Order End Get Set(ByVal value As Order()) _Order = value End Set End Property
I need to get property name 'color' inside the 'order()' array, i am trying ' Order.color ' but its not getting,
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May 18, 2011
I have the following class:
Class MyClass
Property MyInteger as Integer
Set(ByVal value as Integer)
_MyInteger = value
[code]....
As I'm not using any validation etc in my Property, is there any advantage of using a Property in this case, or would it be neater to use:
Class MyClass
Public MyInteger as Integer
End Class
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