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How to use Object in Visual Basic?
All controls in the Visual basic Toolbox are classes. When you do drag and drop those controls into a form, you are actually taking a particular object from that class. Form itself is also a class. Form has several methods such as Load (to load new form in memory but does not show it), Show (to display the form), Unload (to remove the form from memory), and Hide (to hides the form, but does not remove from memory), Move (to move the form), and so on.
To use an object variable is similar to use a conventional variable,
but with one additional step assigning an object to the variable:
First you declare it:
Dim
variable
As
class
Then you assign an object to an object variable with the Set
statement:
Set
variable = [
New
]
object
You declare an object variable in the same way you declare other variables,
with
Dim
,
ReDim
,
Static
,
Private
, or
Public
. The only differences
are the optional
New
keyword and the class argument.
The
New
keyword is used to create object, an instances
of forms, controls, classes defined in class modules, or collections.
The syntax is:
{Dim | ReDim | Static | Private | Public} variable
As [New] class
To set or get the
Property
of an object, it is similar
to assigning to or to obtain value from a variable. To call the
Method
of the object is similar to call function or procedure. To set the value
of a property, use the following syntax:
object.property = expression
Example:
Text1.Top = 200 ' Sets the Top property to 200
twips.
Text1.Visible = True ' Displays the text box.
Text1.Text = "hello" ' Displays 'hello' in the text
To get the value of a property, you use the following syntax:
variable = object.property
Example:
myVar = Text1.Text
Calling an object method is using the following syntax:
[varName =] object.method [arg1, arg2, ,
argN]
For Example:
Me. Show To show the Form
Form1.Circle (1600, 1800), 1200, vbBlue Draw a blue circle with
a 1200-twip radius
Picture = Clipboard.GetData (vbCFBitmap) To returns a picture
from the Clipboard
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