Constructors

A constructor is a special subroutine named New.

Class constructors can take any number of parameters. If you provide no constructors, Visual Basic allows a default empty constructor that takes no parameters. If you provide any constructor, Visual Basic does not provide a default empty constructor. If you want to allow the program to use an empty constructor in that case, you must either provide one or provide a constructor with all optional parameters.

The following code shows a Person class that implements a constructor to make it easier to initialize its properties:

  Public Class Person     Private m_FirstName As String     Public Property FirstName() As String         Get             Return m_FirstName         End Get         Set(ByVal value As String)             m_FirstName = value         End Set     End Property     Private m_LastName As String     Public Property LastName() As String         Get             Return m_LastName         End Get         Set(ByVal value As String)             m_LastName = value         End Set     End Property     ' Empty constructor.     Public Sub New()         m_FirstName = ""         m_LastName = ""     End Sub     ' Initialization constructor.     Public Sub New(ByVal first_name As String, ByVal last_name As String)         m_FirstName = first_name         m_LastName = last_name     End Sub End Class 

Structure constructors are very similar to class constructors with two major exceptions. First, you cannot make an empty structure constructor. Second, Visual Basic always provides a default empty constructor, even if you give the structure other constructors.