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Visual Basic Copy Constructor
Visual Basic Copy Constructor
In visual basic, Copy Constructor is a parameterized constructor that contains a parameter of the same class type. The copy constructor in visual basic is useful whenever we want to initialize a new instance to the values of an existing instance.
In simple words, we can say copy constructor is a constructor which copies the data of one object into another object. Generally, visual basic won’t provide a copy constructor for objects but we can implement ourselves based on our requirements.
Visual Basic Copy Constructor Syntax
Following is the syntax of defining a copy constructor in visual basic programming language.
Class User
' Parameterized Constructor
Public Sub New(ByVal a As String, ByVal b As String)
' your code
End Sub
' Copy Constructor
Public Sub New(ByVal user As User)
' your code
End Sub
End Class
If you observe the above syntax, we created a copy constructor with a parameter of the same class type and it helps us to initialize a new instance to the values of an existing instance.
Visual Basic Copy Constructor Example
Following is the example of creating a copy constructor to initialize a new instance to the values of an existing instance in visual basic programming language.
Module Module1
Class User
Public name, location As String
' Parameterized Constructor
Public Sub New(ByVal a As String, ByVal b As String)
name = a
location = b
End Sub
' Copy Constructor
Public Sub New(ByVal user As User)
name = user.name
location = user.location
End Sub
End Class
Sub Main()
' User object with Parameterized constructor
Dim user As User = New User("Suresh Dasari", "Hyderabad")
' Another User object (user1) by copying user details
Dim user1 As User = New User(user)
user1.name = "Rohini Alavala"
user1.location = "Guntur"
Console.WriteLine(user.name & ", " & user.location)
Console.WriteLine(user1.name & ", " & user1.location)
Console.WriteLine("Press Enter Key to Exit..")
Console.ReadLine()
End Sub
End Module
If you observe the above example, we created an instance of copy constructor (user1) and using an instance of the user object as a parameter type. So, the properties of user object will be sent to user1 object and we are changing the property values of user1 object but those will not effect the user object property values.
When we execute the above visual basic program, we will get the result as shown below.
If you observe the above result, we initialized a new instance to the values of an existing instance but those changes not effected the existing instance values.
This is how we can use copy constructor in a visual basic programming language to create a constructor with the parameter of the same class type based on our requirements.
