LAB
EXERCISE 17: Area Calculator
Goal:
In this exercise, you will learn how to:
1.
Insert the Main Method (Main Entry Point to the Java Program)
2 Import a Java Class Library
3. Create a Superclass
4. Create Subclasses
5. Declare Public Variables
that can be access by Subclasses
6. Create Public Void Method that can be
access by Subclasses
7. Use a Try-Catch block statement for error
handling and exceptions
8. Use the This keyword
to reference a method in a Superclass
9. Create the Object from the
Class
10. Call the Object’s Method
Program Specifications:
Create
an application that prompts the user to input the height, width and color of a
shape. The program will then calculate
and display the area of the shape.
A. Pre-requisites:
1.
Create a folder on your desktop Exercise-17
2. Launch Java EE- Eclipse
Note: You will need to use the Java
Perspective Workbench for this exercise
3. Setup your Eclipse Workspace to point to the Exercise-17
folder
a. Select File-> Switch Workspace
b. Browse and select your Exercie-17 folder as your Workspace.
B. Requirements:
1. Create
a Java Project and name it as AreaCalculator
2. Create
the first Class that will have the Main Method
a.
Name the Class as MainApp
b.
Choose the main method to insert into the
class
3. Create
the second Class that will be the Superclass
a.
Name the Class as Shape
b.
Do not select the main method stub
4. Create
the first Subclass that will inherit the methods
and variables in the Shape class.
Name the Class as Rectangle
5. Create
the second Subclass that will inherit the
methods and variables in the Shape class.
Name the Class as Triangle
6. Create
the third Subclass that will inherit the methods
and variables in the Shape class.
Name the Class as Square
C. Requirements
for the Shape Class:
1. Insert
the import java.util.Scanner class
which will allow data to be inputted from the console.
Insert the line @SuppressWarnings("resource")
2. Declare
the Public variables height
and weight using the double data type.
Declare the Public variable color using the String data type
NOTE: These variables will be accessed
by the subclasses
3. Create
the Public Void Method called getData () that that will prompt the
user to input the data
Note: This method does not return a value. It just executes code
a. Use
the Try-Catch
block statement to perform error
handling.
b. Below
is the code to prompt the user to enter the shape’s height, width and color
Scanner
inputHeight = new Scanner(System.in); |
c. If the user inputs an invalid data, the code
in the Catch block will be executed:
System.out.println("Invalid data
entered.") |
D. Requirements
for the Rectangle Class:
1. The Rectangle class will be a subclass of the
Shape parent class (superclass)
NOTE: A subclass will inherit the methods and variables from the superclass
Add the
keyword "extends Shape" after the name of class
2. Create
the Void Method called getDimensions()
3. Insert
the report header
System.out.println("Rectangle
Shape Dimensions"); |
4. Call
the this.getData() Method from the parent class- Shape
NOTE: Use the “this” keyword to call the
method
5. Calculate
the area of the shape- double area = height * width
6. Display
the results on the screen
//
display the results on the screen |
E. Requirements
for the Triangle Class:
1. The Triangle class will be a subclass of the
Shape parent class (superclass)
NOTE: A subclass will inherit the methods and variables from the superclass
Add the
keyword "extends Shape" after the name of class
2. Create
the Void Method called getDimensions()
3. Insert
the report header
System.out.println("Triangle Shape
Dimensions"); |
4. Call
the this.getData() Method from the parent class- Shape
NOTE: Use the “this” keyword to call the
method
5. Calculate
the area of the shape- double area = (height *
width)/2;
6. Display
the results on the screen
//
display the results on the screen |
F. Requirements
for the Square Class:
1. The Square class will be a subclass of the
Shape parent class (superclass)
NOTE: A subclass will inherit the methods and variables from the superclass
Add the
keyword "extends Shape" after the name of class
2. Create
the Void Method called getDimensions()
3. Insert
the report header
System.out.println("Square Shape
Dimensions"); |
4. Call
the this.getData() Method from the parent class- Shape
NOTE: Use the “this” keyword to call the
method
5. Calculate
the area of the shape- double area = (height * width);
6. Display
the results on the screen
//
display the results on the screen |
G. Requirements for the MainApp Class:
1. Add
comments (documentation)– Program Description, Author and Date
2. Create
the instance of object called areaRec
from the Rectanagle class
Call the object’s method - areaRec.getDimensions()
3. Create
the instance of object called areaTri
from the Triangle class
Call the object’s method - areaTri.getDimensions()
4. Create
the instance of object called areaSqr
from the Square class
Call the object’s method areaSqr.getDimensions()
H. Test:
1. Save your Java code
2. Compile and run your Java program.
3. Verify there is no syntax, logical or run-time
errors.
4. Use the following set of test data to
determine if the application is running properly
5.
I. Submit your exercise in the Canvas Lab
Exercise #17 Drop Box.
1. Submit the screen shot of the Eclipse
Workbench window showing the Console output screen.
You can use Paint (save as JPG) or Word to paste the screenshot.
2. Zip up and submit the compressed AreaCalculator subfolder that is in the Exercise-17
folder.
NOTE: Right click on the subfolder and select
Send to “Compress Folder”. The file will
have a file extension of .zip.