String s = "test"; String is a class, so to use it we should create an object of it. But rather we just make a reference of it and give it a value. How is it possible and what concepts are used in it. The metadata of String class shows the following :
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I am trying to start the process with the following parameters When I try to start it though I get an System.nullreferenceexception: Object reference not set to an instance of an object
Dim exepath As String = Application.StartupPath + "inffmpeg.exe"
Dim sr As StreamReader
Dim cmd As String = " -i """ + input + """ -ar 22050 -y """ + output + """"
Dim ffmpegOutput As String
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The book "Beginning ASP .NET 4 in VB 2010" contains the following:NOTE: TaxableProduct inherits from Product.You can also cast in the reverse directionfor example, cast a Productreference to a TaxableProduct reference. The trick here is that this
View 2 RepliesHere is the structure that I have:
Friend Class StandardFormatFile
Friend fileType As String
Friend numberOfSeries As Integer
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I have a class in which some of the fields are also classes.
I can put values in the "normal" properties, but in the others when o try to assign values it gives the: "Object reference not set to an instance of an object"
But the code compiles fine.
dados_Defenicao = New ServiceReference1.draftClaimEntryDefinition
dados_Defenicao.arCode = "123"
dados_Defenicao.claimMarket.warrantyType = "w" - Here it gives the error
If we are within the derived class then ofcource we can use MyBase keyword to access base class's object reference . That's fine , how can we take that base class's object reference outside that derived class's definition.My following code will explain what i want . Actually that is giving error right now, but it is explaining my requirement .
Public Class Base
Public x As String
End Class
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Actually there is error in ReadOnly Property BaseReference's Getter . Error is "Error 1 'MyBase' must be followed by '.' and an identifier. " how can i get base class object reference in Main method ?
I have a Parent Class Called Fuselage that containsfour child classes called Forebody, CenterBody, AftBody, and CrossSection. CrossSection classcontains objects common to Forebody, CenterBody, and Aftbody (example: width). How do I access thewidth property in CrossSection from within the classForebody?
Public Class Fuselage
Dim Forebody As ClsSection
Dim Centerbody As ClsSection
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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"
View 2 RepliesThe code below works for the class that I hard coded "XCCustomers" in my RetrieveIDandName method where I use CType. However, I would like to be able to pass in various classes and property names to get the integer and string LIST returned. For example, in my code below, I would like to also pass in "XCEmployees" to my RetrieveIDandName method. I feel so close... I was hoping someone knew how to use CType where I can pass in the class name as a string variable.
Note, all the other examples I have seen and tried fail because we are using Option Strict On which disallows late binding. That is why I need to use CType.I also studied the "Activator.CreateInstance" code examples to try to get the class reference instance by string name but I was unable to get CType to work with that.When I use obj.GetType.Name or obj.GetType.FullName in place of the "XCCustomers" in CType(obj, XCCustomers)(i)I get the error "Type 'obj.GetType.Name' is not defined" or "Type 'obj.GetType.FullName' is not defined"
'+++++++++++++++++++++++++++++++
Imports DataLaasXC.Business
Imports DataLaasXC.Utilities
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I am trying to make a customer class that will simply make a bunch of controls (hotspots) Visible value = False.
For instance: WinStartSpot.visible = False
Thing is I have roughly 60 "spots" that need to be turned on and off as the user clicks through the program (its a very simple OS simulator) I tried to make a class using boolean return but that failed miserably. how to code a class like that?
Dim db As New DataClasses2DataContext
Dim newvet = From n In db.vets Select n.vetid Distinct
(Label1.Text = newvet.Count.ToString)
this is the error message I am getting:Object reference not set to an instance of an object.
If we are within the derived class then ofcource we can use MyBase keyword to access base class's object reference . That's fine , how can we take that base class's object reference outside that derived class's definition.
My following code will explain what i want . Actually that is giving error right now, but it is explaining my requirement .[code]...
I am attempting to create a new mobile app using VB in visual studio 2008. I select "File" "New Project". Select "Smart Device" in new project window. Select the "Smart Device Project" from templates. Select ".NET Framework 3.5". Select "OK" and get the dreaded "object reference not set to an instance of an object"
View 1 RepliesInterface makes sure a class does have a Method / Property, However is there a way to create an unInterface, making sure that the class does not have a method / property or is there a way to implement something that will unimplement every other implements except for itself?
what i want to do: i've got a class that serves as a storage for information only, so i decided to give it a blank interface IBank, the other classes that share this feature will implement this interface. they should not implement any other interface the use is that when i seek out the interface of a class and realise that its IBank i know that its just a class for info storage.
This is something that has been bugging me for a while as it is easily fixed but not desirable.I have a DataGridView that has 5 columns. The first is called ID.In vb.net the following line gives an error "Object reference not set to an instance of an object": dgvJobs.Columns("ID").Visible = False ' ERROR dgvJobs.Columns(0).Visible = False ' OK
Obviously using the name is much better than a hard coded value to reference the column but wondering if there is anything i can do to get this to work correctly?The datagridview datasource is BindingSource control with the datasource being a dataset.
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MVC 3 razor VB.NET project. I have resorted to manual building a list for a drop down box so I can insure certain values are available in the select list and also to control what the first item is in the list. The below is my code snippet for the part that is giving me problems..
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dim myCollection as new Specialized.StringCollection
dim myFoundThings as new ArrayList
dim index as Integer
dim newResultMemberName as String
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This is part of some code that will run without user interaction once it's spinning away, and I need to create a unique object from some items found in a StringCollection, naming the objects using information found in the strings stored in that StringCollection.
I want to create a class is it where I can do...
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How do I do this? Do i create a class and create a instance of CarData? but how do I add Color and Year etc to it?
I am trying to make an app that interfaces with Salesforce. Now within salesforce you can customize your database to have any tables or fields that you want/need What I am trying to do is once I do my query, salesforce has your query results returned as a salesforce object. My app basically manages info in salesforce based on rules, sometimes people may need to customize those rules based on fields in the database, however because I dont know what kinds of fields are in their particular database I need to do it programatically...
SO what I want to do is reference the objects property via a string text property name... i.e. if they use a field called "IsFromLebanon" as a boolean I want to be able to access QueryResult.IsFromLebanon. but since I dont know if that field exists or not I dont know how to access its property without spelling out each time. I know clearly thats not going to work, but I dont know how to access the property name without KNOWING the property is going to be there, does that make sense? I dont know if I am making sense or not, it makes perfect sense in my head
I am developing an IT Asset Tracking application using VB 2005 and SQL Server 2005 Express edition. Will I need to create classes to represent objects such as Computers, Printers, Scanners/Faxes, Contracts, Purchase Orders etc or are there any other approaches.For example, if I am correct, I will have a class called Computer and its properties will include Make,Model,CPU,Hard Disk,Memory etc. Is this the right approach.
Computers can be split up into Desktop PC's, Servers and Notebooks. Would I have to create separate classes for these as well or would they be ok under the Computer class.Once I create an object from the class, how can I use the object to interact with the SQL db.I am a beginner to VB.NET 2005 therefore I am slowly getting to grips with OOP.
How does the GC dispose objects created in the following 2 scenarios?
1)
Private Function DoSomething() As Boolean
Return New DatabaseManager().Insert()
End Function
2)
Private Function DoSomething() As Boolean
Dim mngr As New DatabaseManager()
Return mngr.Insert()
End Function
In Option 1, I don't create local variable to hold the reference of the object. In Option 2, I hold the reference in local variable.What option is better and why? (if any)
'This code usualy works when placed within the forms code, however I am wanting to create a class with several text manipulators. The error says System.windows.Controls is not defined
Imports System.Object
Imports System.Windows.Forms.Form[code].....
I'm trying to reference a public property from a string. How can this be done in vb.net?I have the text value of "FirstName" stored in strucParam(i).TxtPropertyName.[code]...
View 1 RepliesI want to make a hashtable of object references and I want a different object's reference to be the key. How can I do this in vb.net? In java (assuming I am using the default toString method and that add() takes a string as a key and an object ref as the value) this would be something like: hashtable.add(obj1.toString(), obj2)
I do not want to use a vb.net gethashcode() function because I want deep clones of objects to have different identifiers. A related question is what is the default toString in vb.net? How can I get a string that represents an object reference in vb.net?
Is it possible using Reflection or some other method to obtain a reference to a specific class instance from the name of that class instance? For example the framework for the applications I develop heavily uses public class instances such as:
Public bMyreference as MyReference = new MyReference
Then throughout the application bMyReference is used by custom controls and code. One of the properties of the custom controls is the "FieldName" which references a Property in these class instances (bMyReference.MyField) as a string. What I would like to be able to do is analyze this string "bMyReference.MyField" and then refer back to the actual Instance/Property.
In VB6 I would use an EVAL or something simular to convert the string to an actual object but this obviously doesn't work in VB.net. What I'm picturing is something like this:
Dim FieldName as String = MyControl.FieldName ' sets FielName to bMyReference.MyField
Dim FieldObject() as String = FieldName.Split(".") ' Split into the Object / Property
Dim myInstance as Object = ......... ' Obtain a reference to the Instance and set as myInstance
Dim myProperty = myInstance.GetType().GetProperty(FieldObject(1))
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How can I modify it so that "UserControl_appName" is not hard coded. I would like to pass it as a string.
Here is my code
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I get an error at the ReadContents(0) = FilePath line saying "Object reference not set to an instance of an object", but the message box shows that "FilePath" holds the file path string.
Under component services, a COM+ component is used by the company, right-clicking it and choosing 'Activation' tab will show the 'constructor string' that is used for DB server connection by all applications. How can I access it the simplest way possible?
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I have a class library that contains a number of classes. I would like to dynamically create an instance of one of these classes, set its properties, and call a method.
Example:
Public Interface IExample
Sub DoSomething()
End Interface
Public Class ExampleClass
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how find an object's type when it is a subclass of another object and I only know the string value of the object's type's name.
I created the follwing classes:
Public Class word
End Class
Public Class noun
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Using 'TypeOf', I correctly see that pn is a properNoun, a noun and a word. The problem is, using 'GetType' to check pn against a string value, I can only see that pn is a properNoun, not that its parent classes are noun and word.
Is there a way to check pn against the string value "noun" or "word" and get back a positive result, indicating that pn is indeed a noun and a word as well as a properNoun?