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Posted on 2006-04-09
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When we write a program, whatever it is, and then create a class, let say, "MySample". When we need to use MySample, we need to instantiated using New. If we use a class, for example, Arraylist, or any other classes, do we need to use New, always?
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Question by:VBdotnet2005
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by:PockyMaster
ID: 16414604
You need to use new in case you use an instance

Methods you will call on the instance will generally do something with your instance.

But there are also methods, referred to as 'Shared' in VB.NET.

These are methods you can call without creating an instance first, e.g.

String.Format(...)

ArrayList got a few Shared Methods as well.

To make your code readable, don't confuse yourself and call the shared methods on instances.

e.g.

Dim s1 as String = "string1"
Dim s2 as String = "string2"

'working but confusing
MessageBox.Show (s1.Copy("s2"))

'wrong
s1.Copy("s2")
MessageBox.Show(s1)

'right
s1 = String.Copy("s2")

MessageBox.Show(s1)

Hope its more clear now...
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by:VBdotnet2005
ID: 16414676
'But there are also methods, referred to as 'Shared' in VB.NET.

Does shared  method always use in Class?

Private Shared mintCount As Integer  

or


 Public Shared Function Speed(ByVal x As Integer) As Integer
        Return x

    End Function
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Author Comment

by:VBdotnet2005
ID: 16414683
...so that we don't need to instanciate it
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PockyMaster earned 500 total points
ID: 16414801
Yeah, you can do like this, but that is used for methods that do not interfere with member variables in your class. You cannot access instance methods from a shared method.

Most of the time your class will contain some data as well, and in that case, you will probably choose to use the non-shared methods.

Shared you will use if you got some kind of functionality that belongs to a class but does not interfere with the class itself.

Think like:
Shared can use in e.g. a math class (Generally speaking)
Non-shared e.g. in a collection class

This is not ALWAYS the case, but to give you a pointer what to think about
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