LAB EXERCISE 20: Paint Job Estimator

Goal: In this exercise, you will learn how to:
1. Create Packages containing Classes
2. Insert the Main Method (Main Entry Point to the Java Program)
3 Import a Java Class Package and Java Library
4. Create a Superclass
5. Create Subclasses
6. Declare Public Variables that can be accessed by a Subclass
7. Declare Constant Variables
8. Create a Constructors
9. Use for the For Loop and running total variables
10. Use a Try-Catch block statement for error handling and exceptions
11. Create the Object from the Class
12. Call the Object’s Variables

Program Specifications:
Create an application that allows the user to enter the number of rooms to be painted and the price of the paint per gallon.
Assume for every 115 square feet of wall space that one gallon of paint and eight hours of labor are required. The hourly wage rate is $18per hour.

The application should display the following information:
1) Number of gallons of painted requires
2) Hours of labor required
3) Cost of the paint
4) Labor charges
5) Total cost of the paint job.

A. Pre-requisites:
1. Create a folder on your desktop Exercise-20

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-20 folder
a. Select File-> Switch Workspace
b. Browse and select your Exercie-20 folder as your Workspace.

B. Requirements:

1. Create a Java Project and name it as PaintJobEstimator

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 1st Package called residentialPaintJobs and create two Classes in the package:

a. Create a class called RoomsPainted. This will be the superclass (parent) of the Cost class
b. Create a class called Cost. This subclass will inherit the methods and variables of the RoomsPained superclass

4. Create the 2nd Package called buildingPaintJobs and create two Classes in the package:

5. Below is the folder structure of the Project:

C. Requirements for the RoomsPainted Class in the residentialPaintJobs Package:

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 numRooms and pricePerGallon using the double data type.
NOTE: These variables will be accessed by the subclass

3. Create the Constructor called RoomsPainted() that that will prompt the user to input the data
a. Use a try-catch block to perform error handling if invalid data is inputted.

// declare the scanner object that will be used to input the number of rooms to be painted
Scanner input1= new Scanner(System.in);
System.out.print("Enter the number of rooms to be painted: ");
numRooms = input1.nextDouble(); // assign the input value to the variable

// declare the scanner object that will be used to input the price of paint per gallon
Scanner input2= new Scanner(System.in);
System.out.print("Enter the price of the paint per gallon: $");
pricePerGallon = input2.nextDouble(); // assign the input value to the variable

b. In the catch block, display “Invalid data entered” message

System.out.println("Invalid Data Entered")

D. Requirements for the Cost Class in the residentialPaintJobs Package:

1. Insert the import java.util.Scanner class which will allow data to be inputted from the console.

2. The Cost class will be a subclass of the RoomsPainted parent class (superclass)
NOTE: A subclass will inherit the methods and variables from the superclass

Add the keyword "extends RoomsPainted" after the name of class

3. Declare the local variables squareFeet and totalSquareFeet using the double data type

4. Declare the public variables as double that will be called from the object in the MainApp
totalGallonsReq, totalHoursLaborReq, costOfPaint, laborCost and totalCost

5. Declare the local static constant variables as double and initialize
HOURLYRATE = 18, WALLSPACE = 115, LABORHOURS = 8

6. Create the Constructor called Cost () and declare as public. This special method will prompt the user to input the data
a. Declare the scanner object used to input the square feet for each room

Scanner input1= new Scanner(System.in)

b. Use the For Loop to enter the square feet for each room and
accumulate a running total of the square feet of rooms to paint

System.out.print("Enter the square feet of room " + (i+1) + " :");
squareFeet = input1.nextDouble(); // assign the input value to the variable

// running total of the square feet of room(s) to paint
totalSquareFeet= squareFeet + totalSquareFeet;

c. Close the scanner object: input1.close()

d. Calculate the total paint gallons required:
totalGallonsReq = totalSquareFeet/ WALLSPACE

e. Calculate the labor hours required to paint all rooms:
totalHoursLaborReq = (totalSquareFeet/WALLSPACE) * LABORHOURS

f. Calculate the paint and labor cost and total cost:
costOfPaint = totalGallonsReq * pricePerGallon

laborCost = totalHoursLaborReq * HOURLYRATE

totalCost = costOfPaint + laborCost

E. Requirements for the MainApp Class in the default package:

1. Add comments (documentation)– Program Description, Author and Date

2. Import the Residential package containing the classes: import residentialPaintJobs.*

3. Create the instance of the object - paintjob from the Cost class: Cost paintJob = new Cost()

4. Display the required results on the console

System.out.println();
System.out.print("Number of Gallons of Paint Required: ");
System.out.format("%.2f", paintJob.totalGallonsReq);

System.out.println();
System.out.print("Hours of Labor Required: ");
System.out.format("%.2f", paintJob.totalHoursLaborReq);

System.out.println();
System.out.print("Cost of the Paint: ");
System.out.format("$%.2f", paintJob.costOfPaint);

System.out.println();
System.out.print("Labor Cost: " );
System.out.format("$%.2f", paintJob.laborCost);

System.out.println();
System.out.print("Total Cost: ");
System.out.format("$%.2f", paintJob.totalCost);

F. 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

G. Submit your exercise in the Canvas Lab Exercise #20 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 PaintJobEstimator subfolder that is in the Exercise-20 folder.
NOTE: Right click on the subfolder and select Send to “Compress Folder”. The file will have a file extension of .zip.