Creating An Object Array Of Different Object Types?
Mar 29, 2010
I am having some trouble creating an object array of different object types. Here is what I have so far:
Public Sub New()
Dim b1 As New Book("Book Title 1", "Gold Book Publisher", 1.0, "Bob Jones", "192DJDJD212", "01/02/10")
Dim b2 As New Book("Book Title 2", "Gold Book Publisher", 1.0, "Bob Jones", "192DJDJD212", "01/02/10")
Dim b3 As New Book("Book Title 3", "Gold Book Publisher", 1.0, "Bob Jones", "192DJDJD212", "01/02/10")
[code]....
If I define the array As Book (Public publicationArray(6) As Book) or Magazine (Public publicationArray(6) As Magazine) I am able to access the properties of that class but not both. I think I need to define a type for each array instance but not sure how to do this.
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Jan 1, 2008
I have set my datasource on my datagridview to be a subset of rows as follows:
dg.DataSource = myDataSet.testTable.Select("id=" & id)
But I get a runtime error that Operator '=' is not defined for types 'Object' and '1-dimensional array of DataRow' There should be an easy way to do this that doesn't involve creating new tables, etc.
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Jun 23, 2012
I'm trying to create a pivot table by opening an Excel file from my drive.But I'm receiving the error saying "Object reference not set to an instance of an object".[code]
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Apr 13, 2012
I'm having this problem with my code and cannot seem to get past it although it was working fine before. The error is "An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object." The code is:
CODE:
I am trying to get information to be pulled out of a database and show in text boxes on another form (frmviewsdets). The error occurs when it gets to the line frmviewsdets.txtsnumber.Text = rdr("StudentNumber") and even when a breakpoint is applied there it just moves on to the next and so on.
I have tried to show frmviewsdets before I pull the data out of the database beut I get the same message.
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Nov 1, 2009
I have a class with a Property called 'Value' which is of type Object.Value can be of any type, a structure, a class, an array, IList etc.My problem is with the setter and determining whether the value has changed or not.This is simple enough for value types, but reference types and lists present a problem.For a class, would you assume that the Equals method has been implemented correctly, or just assume that the value has changed every time the setter is called?If I did assume it's changed, then perhaps I should assume it for value types as well, so that the behaviour is consistent.
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Aug 6, 2010
Here is the structure that I have:
Friend Class StandardFormatFile
Friend fileType As String
Friend numberOfSeries As Integer
[code].....
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Apr 30, 2009
WTF, here's my code...
Public Class Form1
Dim BIT01 As Integer = BIT_01.Text
Dim Value As Integer = TB_OutPut.Text
[code].....
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Nov 1, 2011
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..
[Code]...
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Mar 4, 2009
I have an interface that describes an specialized list in my application...
[Code]....
Is there a way to make an interface serializable, or am I going to have to convert each of my objects into a concrete class implementing the interface, and then return that class?
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Jul 10, 2010
I am somewhat new to object oriented programming and am attempting to flatten a Linq object hierarchy by using a shim class.how to initalize a derived class with property values from a base class?I have two objects, a base object with about 100 properties, and a derived object which inherits from the base object and adds a few additional properties beyond those of the base object. My simple constructor creates the derived object, but I am looking for a way to initialize the derived object properties with values from the base object.Right now I am using reflection to iterate over the properties individually and I suspect there may be a better way. The following example shows my shim class constructor for the derived class, and two properties:
newProperty1 - a new string property of the derived class
flattenedProperty2 - a new string property of the derived class, copied from a 2nd-level object of the base class
Code example:
Public Class derivedObj
Inherits baseObj
Private _newProperty1 As String[code].......
Is this the correct constructor approach to flatten the object hierarchy using a shim class? My second question relates to initialization of properties in the derived class. The constructor above creates the derived object, but what is the best way to initialize the derived object properties with values from the base object? The following code uses reflection to iterate over the properties individually, but I suspect there may be a better way.
Code example:
' property names are in the string array fieldNames
'baseObjQuery is an ienumerable of baseObj
'derivedObjList is a list of derivedObj[code].....
Is there a simple way to initialize values for the properties in the derived object based upon the values of the common properties in the base object?
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Sep 27, 2010
I understand that different data types have different uses, String for text, Integer for numerical ect. However, if the Object type can be used for ALL types and supportive of everthign then why should i worry about using correct data types such as string and integer if i can just use "Object" for them all and it will work.I could do
Dim Test as Object = "John"
or i could do
Dim Test as String = "John"
They both do the same thing; there must be something very important im missing here but can only think of one thing that it could be; Memory Management.I think that by using a type such as object may take up more memory than using string?
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Jul 29, 2010
I am building an ASP.NET application that needs dynamic tables. That's another issue that I've already posted about (and gotten a pretty good response!). Now, I'm running into another issue - I want to add new rows to my table, but given that I will have 10-12 tables on one page, each containing different objects in their rows (text boxes, check boxes, etc.) I need a way of simply generically adding a new row that has the same objects as the first row in the table. Here's my code:
Private Sub AddTableRow(ByRef originalTable As System.Web.UI.WebControls.Table)
Dim originalRow As System.Web.UI.WebControls.TableRow = originalTable.Rows(1)
Dim insertingRow As New System.Web.UI.WebControls.TableRow[code]......
Stepping through with a debugger, I see that this strategy is working - but the additional table row still doesn't appear...and still does when I do this statically.
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Feb 22, 2010
The last line in the code below throws the error. Is it because I haven't intialized the size of the byte array?
Public Class Form1
Private toSocket_IPP As Byte()
Public Sub New()
[code].....
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Feb 3, 2011
Here's what I'm looking to do. I have an array of objects that all implement a particular interface. What I want to do is search that array of objects for a particular object type.I have to do this in several places, so I'm trying to create a function where I pass in the object array and the type that I'm searching for, and have that function return the object that matches that type - or nothing if no match is found.I wrote the following, but it isn't working, so I'm missing something:
[code]...
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Jan 11, 2011
This is my code in vb.net 2010:
Structure feature_s
Public feature() As Integer
End Structure
[CODE]............
I keep on getting a error "object not set to an instance of an object" i am puzzled by this since there are no errors until i run the program. I redim the array. the build is fine. the exception is handled. and the structures and "dims are all global"
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Apr 15, 2011
I'm trying to figure out 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:
HTML
Public Class word
End Class
Public Class noun[code]....
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?
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Feb 10, 2010
My quest is in regards to xml serialization. I need to get rid of the root node of a collection. I don't have access to my source now so I'll just try to generalize
public class SomeClass
'...some other properties...
<XMLArray(isnullable:=true), _
<XMLArrayitem(datatype:=(getType(object1)), _
[code]....
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Nov 9, 2011
I am having problems with my code, where I get the "Object cannot be cast from DBNull to other types" message when Insert(). I get the message on every Insert to this table, even though the data is successfully inserted. If I Update the same data after Insert(), it does so without error. I have checked my values and none of them are DBNull. Even when the same values are passed on Insert that are passed on Update.
My code is :
Private Sub Save()
Dim bo As tbl_GL
bo = New tbl_GL()
bo.ConnectionString = AppConfig.ConnectString
[Code] .....
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Feb 15, 2011
Given a list of objects, I'd like to print a string version of them just in case the object.ToString() result is a relevant string.By that I mean I don't want to get things like:
obj.ToString() -> System.Collections.Generic.List`1[MyLib.Dude]
obj.ToString() -> System.Collections.Generic.Dictionary`2[System.Int32,System.DateTime]
obj.ToString() -> System.Byte[]
But I want to get things like:
obj.ToString() -> Hi
obj.ToString() -> 129847.123
obj.ToString() -> Id = 123
What should be the best way to implement this in a method:
Public Sub PrintInterestingStuffOnly(ByVal coolList as Ilist(Of Object))
For Each obj in coolList
'insert solution here
[code].....
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Jun 14, 2011
I didn't think it fair to post a comment on Fredrik Mörk's answer in this 2 year old post, so I thought I'd just ask it as a new question instead..NB: This is not a critiscm of the answer in any way, I'm simply trying to understand this all before delving into memory management / the marshal class.
In that answer, the function GetByteArray allocates memory to each object within the given array, within a loop.Would the GetByteArray function on the aforementioned post have benefited at all from allocating memory for the total size of the provided array:
Dim arrayBufferPtr = Marshal.AllocHGlobal(Marshal.SizeOf(<arrayElement>) * <array>.Count)
I just wonder if allocating the memory, as shown in the answer, causes any kind of fragmentation? Assuming there may be fragmentation, would there be much of an impact to be concerned with? Would allocating the memory in the way I've shown force you to call IntPtr.ToInt## to obtain pointer offsets from the overall allocation pointer, and therefore force you to check the underlying architecture to ensure the correct method is used*1 or is there a better way? (ToInt32/ToInt64 depending on x86/64?)
*1 I read elsewhere that calling the wrong IntPtr.ToInt## will cause overflow exceptions. What I mean by that statement is would I use:
Dim anOffsetPtr As New IntPtr(arrayBufferPtr.ToInt## + (loopIndex * <arrayElementSize>))
I've read through a few articles on the VB.Net Marshal class and memory allocation; listed below, but if you know fo any other good articles I'm all ears![URL]..
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Jul 29, 2011
I am getting following error whenever I want to use IIf function inside entity framework query.
LINQ to Entities does not recognize the method 'System.Object IIf(Boolean, System.Object, System.Object)' method, and this method cannot be translated into a store expression.
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Apr 24, 2011
Suppose a click event is fired and a particular gridview datasource is set in the code behind page by retrieving a data table from a business logic class.
So programmatically speaking, what is the main difference between the two set of code listed below.
Private Sub btnGetGridViewData_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim myBLL as New BusinessLogicClass
[code]....
I guess my main question is, what is the purpose of creating a new instance of an object in the above scenario?
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Mar 25, 2010
In the code below (which I just wrote here - it closely mirrors what my actual code is...) the problem is with the line:
Thing.ThingObject.Add(MyObject)
It says: "Object reference not set to an instance of an object" Yes - it is "nothing" before I try to use the Add method so I must be doing something basic and wrong.The object I am trying to add is fine - I can tell you it is correct, it's just that I apparently cannot use the .add method on the Thing.ThingObject until it is properly created - which I have apparently not done.
Private Sub DoThing()
Dim MyObject as New Object
MyObject = MakeMyObject
[code]....
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Nov 21, 2006
I'm trying to create 3 instances of the the Workshop selector form for the 3 individuals that I have inthe listbox to appear when I first run the program.
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Jun 1, 2012
I have a class defined as follows. How to create Product object with part1 and part2 values in Component Field
Partial Public Class Product
Private ComponentField() As Component
Public Property ComponentProperty() As Component()
[code]....
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Apr 9, 2010
My project is done on vb,net& sql2000 but it is not running and showing error -
" object is not creating an instance " what to do ?
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Mar 4, 2012
I am creating a dll with all the functions and subroutines that I use all the time and I decided to create a function that I can pass different types of array to so the function obviously (or not) would have an array of type object. Now I no you can pass any type into an object type but when I pass an integer array into an object array I get an error.
value of type '1-dimensional array of integer' cannot be converted to '1-dimensional array of object' because 'integer' is not a reference type.
Shared Function CompareArray(ByVal FirstArray() As Object, ByVal SecondArray() As Object, Optional ByRef ErrorMessage As String = "") As Boolean
Dim IntArrayOne() As Integer = {1,2,3,4,5} Dim IntArrayTwo() As Integer = {1,2,3,5,6} Dim IsSame As Boolean = False IsSame = CompareArray(IntArrayOne(), IntArrayTwo())
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Sep 29, 2011
my aim is to create a new instance box at the push of a button, the box has strings name and Id to be filled concatenating the auto generated ID i.e. 0 to 210 plus a string "Box" added by the user. I had problems earlier creating a structure within the class box, frankly I am not sure if the code below will work, as i try to run it in VB I get an error indicating that I am using the variables strBoxPositions() and strBoxNumbers() without assigning a value to it. The thing is the strBoxPositions() should automatically be filled by arrPosition() which will be created at the same time the new object box is created and the strNumbers() will be created with empty strings to be filled at latter stage by the used as and when necessary.
how could I initialise those arrays to get the program to run and perhaps ill be able to see if the code works or not, or just correct this code with a better way of code with comments, also if possible some indication on how could I update the strNumbers array inputing the strings one at a time on a text box field.
Public class form1
Public Class Box
Public intBoxID As Integer
[Code].....
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Jul 15, 2011
i'm having problems creating a public string varialble in a class or module. i am going to be refering to it in many forms so this way i only will have to change the text of the string once and not on each form.Currently when i try to use the new string variable as an object variable from another form, it isnt showing up as an object i can reference. [code]
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Jan 23, 2010
I have an application with 6 cars 'racing' across the screen. Ideally I would like the random function to move only 1 of the 6 objects (cars) at one time and then loop until one car reaches a predefined finish line. However I'm not sure if this is achievable. Would I need to create a random number then create if statements?
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