CSC139 Chapter 10 Lab Assignment (2)PolymorphismObjectivesIn.docx
- 1. CSC139 Chapter 10 Lab Assignment (2) Polymorphism Objectives In this lab assignment, students will learn: - How to design and define interface - How to implement methods declared in interface - How to implement polymorphism Goals In this lab assignment, students will demonstrate the abilities to: - Design and define interface - Implement methods declared in interface - Implement polymorphism Grading - Define interface (30 pts) - Define base / derived classes (40 pts) - Define tester program to implement polymorphism (30 pts) In this lab you will create an interface inheritance hierarchy and perform polymorphism in a tester program. The following is the simplified UML for the hierarchy: 1. Create a Console Application Project called “InterfaceApp”.
- 2. 2. Rename the “Module1.vb” as “IShapeTester.vb” 3. Add a class definition, modify it to an Interface named “IShape” which has two members: a. Function ToString() : String b. Function CalculateArea() :Double 4. Add a class definition named “TwoDShape”, which is an abstract base class, the following members should be included: a. xValue: Integer ---- instance variable b. yValue: Integer ---- instance variable c. Sub New(Integer, Integer) ---- constructor d. Property X():Integer ---- get and set xValue e. Property Y():Integer ---- get and set yValue f. Function CalculateArea():Double ---- “MustOverride” function and implements IShape’s CalculateArea() function g. Function ToString() ---- Overrides ToString() function in Object and implements IShape’s method, display x and y coordinate on the console window (use the following definition) Public Overrides Function ToString() As String Implements IShape.ToString Return ("X-coordinate: " & vbTab & xValue & vbCrLf & "Y- coordinate: " & vbTab & yValue) End Function 5. Add a class definition named “Circle”, which inherits from “TwoDShape” class and includes the following members: a. radiusValue: Double --- instance variable, radius of a circle b. Sub New(Integer, Integer, Double) --- constructor c. Property Radius():Double --- get and set radiusValue
- 3. d. Function CalculateArea():Double ---- override and implement the abstract method in base class Shape, calculate area of a circle using: radiusValue * radiusValue * 3.14 e. Function ToString() ----- use Convert.ToString(Me.GetType()) to display the type of shape, then display X and Y coordinates by calling base class’s ToString() function, finally, display radius value on console window (use the following definition) Public Overrides Function ToString() As String Return (Convert.ToString(Me.GetType()) & vbCrLf & MyBase.ToString() & vbCrLf & "Radius: " & vbTab & String.Format("{0:N2}", radiusValue)) End Function 6. Add a class definition named “Square”, which inherit from “TwoDShape” class and include the following members: a. sideValue: Double --- instance variable, side of a square b. Sub New(Integer, Integer, Double) --- constructor c. Property Side():Double --- get and set sideValue d. Function CalculateArea():Double ---- override and implement the abstract method in base class Shape, calculate area of a square using: sideValue * sideValue e. Function ToString() ----- use Convert.ToString(Me.GetType()) to display the type of shape, then display X and Y coordinates by calling base class’s ToString() function, finally, display side value on console
- 4. window (use the following definition) Public Overrides Function ToString() As String Return (Convert.ToString(Me.GetType()) & vbCrLf & MyBase.ToString() & vbCrLf & "Side: " & vbTab & String.Format("{0:N2}", sideValue)) End Function 7. Perform polymorphism in the Module “IShapeTester.vb”: a. Declare 4 objects: s1: a circle object ( center at (2, 4) and radius = 3.0) s2: a square object (center at (1, 5) and side = 4.0) s3: a circle object (center at(3, 6) and radius = 3.5) s4: a square object (center at(6, 3) and side = 6.0) b. Put these 4 objects into an IShape array c. Use a “For” loop to traverse the array and let each object do the following: i. Call ToString() and let it display shape type, x and y coordinates, radius or side value ii. Call CalculateArea() and let it calculate area of a shape, display the area on console window. 8. Here is the sample output window, your program should be performed similarly like this: <<Interface>> IShape + Function ToString() As String
- 5. + Function CalculateArea(): Double TwoDShape - xValue: Integer - yValue: Integer + Sub New(Integer, Integer) + Property X():Integer + Property Y():Integer + Function CalculateArea():Double + Function ToString():Strinbg Square sideValue: Double
- 6. + Sub New(Integer, Integer,Double) + Property Side():Double + Function CalculateArea():Double + Function ToString():Strinbg Circle radiusValue: Double + Sub New(Integer, Integer,Double) + Property Radius():Double + Function CalculateArea():Double + Function ToString():Strinbg