Visual Basic.NET How to Program (PDF)

410 Object-Oriented Programming: Polymorphism Chapter 10
1 ' Fig. 10.9: Employee.vb
2 ' Abstract base class for employee derived classes.
3
4 Public MustInherit Class CEmployee
5
6 Private mFirstName As String
7 Private mLastName As String
8
9 ' constructor
10 Public Sub New(ByVal firstNameValue As String, _
11 ByVal lastNameValue As String)
12
13 FirstName = firstNameValue
14 LastName = lastNameValue
15 End Sub ' New
16
17 ' property FirstName
18 Public Property FirstName() As String
19
20 Get
21 Return mFirstName
22 End Get
23
24 Set(ByVal firstNameValue As String)
25 mFirstName = firstNameValue
26 End Set
27
28 End Property ' FirstName
29
30 ' property LastName
31 Public Property LastName() As String
32
33 Get
34 Return mLastName
35 End Get
36
37 Set(ByVal lastNameValue As String)
38 mLastName = lastNameValue
39 End Set
40
41 End Property ' LastName
42
43 ' obtain String representation of employee
44 Public Overrides Function ToString() As String
45 Return mFirstName & " " & mLastName
46 End Function ' ToString
47
48 ' abstract method that must be implemented for each derived
49 ' class of CEmployee to calculate specific earnings
50 Public MustOverride Function Earnings() As Decimal
51
52 End Class ' CEmployee
Fig. 10.9 MustInherit class CEmployee definition.