My understanding of classes/objects is that you create a class that acts as a "template".From there you simply declare an object of that class and operate directly on that object.eg, object.methods, object.properties etc.That's my limited understanding.I've got a huge form in another project that is crying out for a decent class structure to hold references to a multitude of numbered textboxes.
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I am wondering the best way to store an object in memory that is used in a lot of classes throughout an application. We have multiple databases, 1 per customer. We also have a master table and each row is detailed information about the databases such as database name, server IP it's located and a few config settings.
I have an application that loops through those multiple databases and runs some updates on them. The settings I mentioned above are updated each loop iteration into memory. The application then runs through series of processes that include multiple classes using this data. The data never changes during the processes, only during the loop iteration.
The variables are related to a customer, so I have them stored in a customer class. I suppose I could make all of the members shared or should I use a singleton for the customer class? I've never actually used a singleton, only read they are good in this type of situation. Are there better solutions to this type of scenario? Also, I could have plans for this application to be multithreaded later.
I am at a new company and I am building a wizard for a web app, (.Net/4.0). The user goes to a few separate screens during the wizard process and must return to the original screen before completion of the wizard. This is different from how they normally do this. But this is how it is TO BE DONE.
One option is to store the result of each panel in the main screen in the DB. So then, when the user leaves & redirects back. I could check for a querystring then call a datareader and populate original values appropriately.
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In .net, it's possible to use generics so that a function can accept arguments which support one or more interfaces and derive from a base type, even if there does not exist any single type from which all valid argument types derive. For example, one could say: Sub Foo(Of T As {IInterface1, IInterface2, SomeBaseType})(Param as T) And be allowed to pass any derivative of SomeBaseType which implements both IInterface1 and IInterface2. This will work even if SomeBaseType does not support Interface1 and Interface2, and classes which do implement those interfaces don't share any common ancestor that also implements them. This can be very convenient if one won't need to keep the parameter anywhere after the function has exited. Unfortunately, I can't figure out a way to persist the passed-in parameter in such a way that it can later be passed to a similar function, except perhaps by using Reflection. Is there any nice way of doing that?
The closest I've been able to come up with is to define an interface INest (perhaps not the best name-- thus:
Interface INest(Of Out T)
Function Nest() As T
End Interface
And for any interface that will be used in combination with others or with base-class "constraint", define a generic version as illustrated below:
Interface IFun1
' Any members of the interface go here, e.g. ...'
Sub DoFun1()
[CODE]...
A class which will support multiple interfaces should declare itself as implementing the generic ones, with itself as the type argument.
Class test123a
Inherits sampleBase
Implements IFun1(Of test123a), IFun2(Of test123a), IFun3(Of test123a)
End Class
If that is done, one can define a function argument or class variable that supports multiple constraints thusly: Dim SomeField as IFun1(Of IFun2(Of IFun3(Of sampleBase)))
And then assign to it any class derived from sampleBase, which implements those interfaces. SomeField will implement IFun1; SomeField.Nest will implement IFun2; SomeField.Nest.Nest will implement IFun3. Note that there's no requirement that IFun1, IFun2, IFun3, or sampleBase share any common derivation other than the generic interfaces inheriting from INest(Of T). Note also that, no matter how many INest-derived interfaces a class implements, it only needs to define one implementation of INest(Of T).Nest. Not exactly beautiful, but there are two nice things about it: (1) any concrete class which in fact implements the necessary interfaces can be assigned directly to a field declared as above, without a typecast; (2) while fields which chain the types in a different order are not assignment compatible, they may be typecast to each other. Is there any better way to store something in such a way that it's "known" to support multiple interfaces and derive from a certain base type? Given that one can write such code in a type-safe manner, it would seem like the .net 2.0 CLR could probably support such a thing quite nicely if compilers offered a little assistance.
I was looking through some legacy code we have and I noticed something that struck me as particularly odd.Say we have the concrete class TestClass. TestClass implements the interface ITestClass.What sort of behavior should I expect in the following case, then? (I didn't realize this was even possible)
Dim testClass as TestClass = Nothing
Try
testClass = New ITestClass
[code].....
I create a string array from a bunch of files that were dropped on a control after that i use a loops to pass that data into an array of my pictureObjects object (just stores filePath info and some other things).for some reason after it's been passed to the control the "My.Computer.FileSystem.RenameFile" doesn't seem to work at all... it's a valid file name and everthing.
Dim sFileArray() As String = e.Data.GetData(DataFormats.FileDrop)
'load sFileArray into new array of picureObjects
ReDim dropedPicture(sFileArray.Length)
Dim dropedOnPictureBox As Integer[code]......
I'm adding themes to my application so that the user can customize colors. What is the best way to store colors in SQL for the purposes of retrieving them and setting control colors in VB.Net? As an integer? The RGB value as a string? (There will be colors involved that don't have names, so I can't go the route of storing the name.)
View 3 RepliesI am using vb.net (visual studio 2010) and have made a form application that uses a login screen. All that works but I am having trouble any firm way to encrypt the passwords in the database. The encryption doesn't have to be very high standard as its just for a college project. Whats the best way to encrypt the password into the database? Or just encrypt the password string, I can then sort out the database end myself.
View 2 RepliesI'm obtaining data from a StreamReader.My StreamReader is called "reader" and I'm reading the stream with "responseOutput" like this "responseOutput = reader.ReadToEnd()" And in that bunch of text that I receive I want to FIND and EXTRACT a piece of text and then STORE that extraction in a variable of String type.Here is part of the code I'm referring to:
Dim response = request.GetResponse
Dim responseOutput As String
Dim reader As StreamReader
reader = New StreamReader(response.GetResponseStream())
responseOutput = reader.ReadToEnd()
And here is the text or data that I'm receiving (what I'm about to show you is the result of a "MessageBox.Show(responseOutput)":
<TweetPhotoResponse xmlns="http://tweetphotoapi.com" xmlns:i="http://www.w3.org/2001/XMLSchema-instance"><Large>http://cdn.cloudfiles.mosso.com/c54092/x2_7e143b</Large><MediaId>7e143b</MediaId><MediaUrl>http://tweetphoto.com/8262715</MediaUrl><Medium>http://cdn.cloudfiles.mosso.com/c54102/x2_7e143b</Medium><Original>http://cdn.cloudfiles.mosso.com/c61132/x2_7e143b</Original><PhotoId>8262715</PhotoId><SessionKeyResponse/><Status>OK</Status><Thumbnail>http://cdn.cloudfiles.mosso.com/c54112/x2_7e143b</Thumbnail><UserId>2268670</UserId></TweetPhotoResponse>
And all I want to do, is to extract a specific part of that text, which is the "PhotoId" value (I highlighted it in red), in this case the value is "8262715", and then store it in a variable (I know how to do that I just need the value).The text or data I'm receiving changes only the PhotoId everytime it's requested.
There are "text" files, there are databases, I used to use a record (now called a structure) in a ".dat" file, but I'm having trouble finding documentation support in vs2010. So I'm thinking maybe it's time to move up to ... ? databases? ".txt"s? The current app I'm trying to write will only have a couple of hundred "records" at the very most; Old vb6 command like LenB which would return the size of a file in bytes is no longer, and I can't find how len( .."as byte" of file) would actually be implemented. len( <filename>, as byte) isn't the correct syntax - what is?
Is there some thing less dramatic than a full blown database? Or getting used to how a database uses SQL and all that goes along with that shoud be something to get handy with?
I am trying to store 8 separate pieces of information in a text file (like a database) [but not a SQL database], consisting of integers and strings. How would I use an array to do this? Will an array collect data from text boxes (I also want to display the 8 pieces of information in separate boxes). also how would I save the text file so I can open it again or open a different text file (database?), from within the program?
EDIT: I see I need to use readline and writeline to read/write from a text file but how would I find specific data to show in my boxes?
What is the easiest method of storing data and retrieving it using VB? FYI, I have not used Access before. It will be a movie database that stores title genre, etc. I thought about using a text file but i think thats crude and ran across this site:
View 1 RepliesI have data that I want to store in some type of variable where I can easily access when needed. For example I have:
google.com -> This is a cool website.
yahoo.com -> News website
gmail.com -> Mail website
I want to be able to store those in some type of group so if I go like:
get data of google.com without going through a loop.
In the program I'm working on, there is a 'sign-in' form that pops up for the user to enter first name, last name, and DOB. What I want to do is STORE that information in a text file for FUTURE use by the program (i.e. displaying a list of all previous users of the program).I already know how to use streamwriter to write text to a file, but I would like for the text file to be stored within the program files and also for a new user's data to be appended to that file every time.
Do I simply add the text file to the project files? When I do that, its path is 'My Documents'. How will that affect the program when I publish it? I guess I just don't yet understand what happens when the program is finished and published. The code for the 'Submit' button on the sign-in form is pasted below. At the bottom, I've put a comment to indicate where I want to store the data to a file.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim TxtBox() As String = {TextBox1.Text, TextBox2.Text, TextBox3.Text}
For i As Integer = 0 To 2
If TxtBox(i) = Nothing Then
[code]....
I have an application that gathers data from a SQL database that is used by a 3rd party helpdesk application.My application is pulling out information of the number of hours worked by each engineer for the current and previous 2 months.Also as part of this process, my application works out the target hours for each of those months.
My application has 3 groupboxes whose label is generated at runtime. My application gives the Groupbox1.text the name of the current month, Groupbox2.text the name of the previous month, and Groupbox3.text the name of the month before that (e.g. Mar, Feb, Jan).
What I am trying to do is have 2 text boxes for each month where I can enter the number of engineer holidays taken and the number of public holidays if any. I want to store these values in an XML file, and I guess they need to be stored to match the Groupbox text (i.e. Mar, Feb, Jan).
When the application starts, I need to parse that XML file and re-populate the text boxes with those number of days - BUT if the month has moved on, so that the Groupboxes are now called Apr, Mar, Feb then I want the Mar and Feb data to be loaded, and I want the XML file to be updated so that Apr is added and Jan is removed from it.I want the XML file to keep the current and previous two months figures only.
What I'm trying to accomplish is first of all, adding items in a list box, but while doing so, store data into that item so when the user clicks on it, the data will be brought up into the correct text boxes.
My idea on how this will all work out has to do with array lists. I'm thinking each time an item is added to the list box, an array list is generated containing all the data from the text boxes. The array list would be named as the text of the list box item.
So then when the user clicks on one of the items, it can find that array list easily because of the selected index, and then update the text boxes with the data.
Is the way I'm thinking of possible? If not, or if there is an easier what, what would that be?
I'll try to explain what i'm doing here, i wan't look through a text file, adding certain lines to an individual array element. So i want to build an array with mcode, mTitle, mCredits, mSemester, moduleStats, currentYear <--- this information as an array element. So here is my attempt at the code,
Dim sr As StreamReader = New StreamReader("datasource.txt")
Dim line = sr.ReadLine() ' get each line and store it
Dim currentYear As Integer
[code].....
Here is what I would like to do:
- Store string data from a 'sign in' form into a text file. This text file must be one that is saved even after the user exits the program. The text file must also be one that will stay with the program even after it is published (executable).
- Be able to write to/read from the file for purposes of displaying some or all of that data on a form.
I use an Application Setting to do this - of type 'Specialized String Collection'. I tried this, but for some reason I could not get it to work. It was a good idea, but I need to be able to SEE the data that has been saved, and with a setting it seems like that is not easily done. I've decided that I either need to use a simple text file or a 1-table database for this. I would prefer just a text file, but in either case, it needs to be part of the .exe when published.
I have added a text file to my project, but I am not sure if it will be "included" in the project when I publish it. The path of the file I've added is in 'My Documents', but in my code, I will have to specify the path in order to use Streamwriter. How will this affect the program when I publish it? I felt the need to make a new thread because on my last one we had been mainly talking about settings, and I've decided that isn't the best option for me.
I'm creating a small tool for our team that performs backups of our servers. The plan is to put the tool in a central location so that anyone can use it.I'd like to store, somewhere, the date of the last backup for each server. I was wondering if I could use an application settings (with Application scope) for this? Is this bad practice? If so, what's the best practice? XML? text file? registry?
View 6 RepliesI've got a dictionary<string,string> that I need to access and use on several windows forms. In asp.net, I could store it in Session and use it from any aspx page. How would I do this in forms?
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I am using VS 2010 and I want to read the Text File values and place them into variables. This is my code
Me.OpenFileDialog1.FileName = Nothing
If Me.OpenFileDialog1.ShowDialog = System.Windows.Forms.DialogResult.OK Then
Me.TextBox2.Text = Me.OpenFileDialog1.FileName
filename = Me.TextBox2.Text
End If
[Code] .....
I am unable to move pointer to next line.
Recently I started a project with the goal being to have text that was inputted into a textbox stored within a three dimensional jagged array. The idea is that every time a button is pressed, whatever text that is inputted into the textbox is split into separate elements, where each word occupies its own element in the array. So for example, if a poem were entered into the textbox and the button clicked, each word of the poem would be assigned to a discrete element in the vertical dimension, and each line of the poem assigned an element in the horizontal dimension. After the text is stored into the 3D jagged array, the text should be cleared from the textbox and a counter should then ensure that on the next button press, the new text inputted into the textbox is stored in a discrete element of the array. Below is the code I have written so far, but I know that I am far from having anything might accomplish what I have just described.
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what I have to do is read the 5 names inside the Sequential Access File and store them in an array. I'v encountered a problems in storing it in an array. Here's the code
Dim infile As IO.StreamReader
Dim names(4) As String
Dim filename As String = "names.txt"
[Code]....
Theres an error in the code saying that a string cannot be converted into a one dimensional array.
"I need to create a program that will allow the user to enter in 10 test grades from a class. I need to store these grades into an array, and use a loop to add up the total. Then I'll need to output the average, and the letter grade for the average using:
90 - 100 A
80 - 89 B
70 - 79 C
60 - 69 D
Below 60 F"
That's all it needs to do. Here is some code that shows you that the only thing I know how to do is (allow the user to enter in 10 test grades from a class.) The rest I'm so lost on and have a crappy instructor. This assignment is due tomorrow, but the instructor is not available over the weekend.
Here is my This is all I have:
Dim MyNumbers(9) As Integer
Dim Total As Integer
Dim i As Integer
[Code]....
I want to learn how to rotate an object by direction and speed and also how to move an object using the arrow keys?
View 2 RepliesI'm using the following code to try and search a listview (I got it from msdn):
Dim atem As New ListViewItem = ListView1.FindItemWithText(TextBox2.Text, True, 0, True)
If atem IsNot Nothing Then
ListView1.TopItem = atem
End If
Then I got the " Object reference not set to an instance of an object" error highlighting the following line: ListView1.TopItem = atem So then I tried this:
Dim atem As New ListViewItem atem = ListView1.FindItemWithText(TextBox2.Text, True, 0, True)
If atem IsNot Nothing Then ListView1.TopItem = atem End If it still isn't working.
I am struggling with the following - I try to add a value to a list, where the list is defined in a structure.
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I get error (Object reference not set to an instance of an object)trying to read a reg key, it stops after the first msgBox which shows MyRegKey value it shows a blank value
Dim MyReg As Microsoft.Win32.RegistryKey = Microsoft.Win32.RegistryKey.OpenRemoteBaseKey(Microsoft.Win32.RegistryHive.CurrentUser, (OldPCTxtBx.Text))
Dim MyRegKey As Microsoft.Win32.RegistryKey
[code]...
I have a treeview with a contextmenu. I'm trying to disbable specific items in the contextmenu when the user doesn't have a node clicked, but each try gives me the same error: "Object reference not set to an instance of an object."I tried several methods in the Mouse_Down-event (IsSelected, etc), this was my last:
If .Nodes.Count > 0 Then
If .SelectedNode.Text <> "" Then ' <<< this line is highlighted
enable_expl_mnu() ' enable the contextmenu
[code]....
I get the error, Object reference not set to an instance of an object., on:
vb
For Each comboItem As String In My.Settings.ComboBox1
That code is in:
vb
Private Sub Me_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Me.Load
For Each comboItem As String In My.Settings.ComboBox1
[code]....
I am trying to get it to load those settings when the program loads up, VS does not report that program till i attempt to run in debug. Before the program is even loaded that happens.
