Question

I am required to use the try - catch block to validate the input as the test data uses a word "Thirty" and not numbers. The program needs to validate that input, throw an exception and then display the error message. If I don't use the try - catch method I end up with program crashing. My issue is that I can't get the try - catch portion to work. Can you please help? I have attached what I have so far. The last time I asked this question they ignored the try - catch piece and just reposted my code. It is important that the try - catch piece works and this is the second time I have had to ask the same question.

Thanks,

Overview

Many Java programs that you create will receive and process user input. In order to ensure that user input is accurate, you will need to use input validation and exception handling. For example, if you ask for a zip code, you want to ensure the user inputs a five-digit number. In this activity, you are given “buggy” code for a paint program that calculates the number of cans of paint required to paint a wall, given the wall’s height and width. You will need to debug the code and improve it by adding code to validate user input and handle exceptions.

Prompt

For this assignment, you will complete the paint program by debugging the original code and adding code that validates user input and handles exceptions. Use the Uploading Files to Eclipse and the Downloading Files from Eclipse Tutorial tutorials to help you with this project.

• Debugging
  • Open the Virtual Lab by clicking on the link in the Virtual Lab Access module. Then open your IDE. Upload the Paint1.zip folder and review the code for the Paint1.java file.
  • Find and fix the three errors in the given code.
  • Use the input values below to test your program. If you found and fixed all errors, your output should exactly match what is below.
    TIP: When you run your program in Eclipse, it will prompt you to enter input in the Console window. If you cannot find this window, go to Window, then Show View, then Console.

• Input Validation and Exception Handling
  • Review the code, looking for the two code blocks where user input is required.
  • Implement a do-while loop in both blocks of code to ensure that input is valid and any exceptions are handled.
    TIP: Consider using a try-catch block for exception handling, but it is not required.
  • Use the two sample invalid inputs below to test your program. Your program should respond to each by prompting the user to enter valid input. This should continue to loop until valid input is received.

THINK: Why is 0 invalid input for this problem? What is the user being asked to input?

This is what I have so far but I can't get the try, throw and catch to work. Can you please help?

import java.util.Scanner;

public class Paint1 {

    public static void main(String[] args) {
        Scanner scnr = new Scanner(System.in);
        double wallHeight = 0.0;
        double wallWidth = 0.0;
        double wallArea = 0.0;
        double gallonsPaintNeeded = 0.0;
      
        final double squareFeetPerGallons = 350.0;
      
        // Implement a do-while loop to ensure input is valid
        // Prompt user to input wall's height
      
        //Do/While loop examples in 3.18 of Zybooks
      
        do {
        System.out.println("Enter wall height (feet): ");
        wallHeight = scnr.nextDouble();
        } while ((wallHeight <= 0));
      

        // Implement a do-while loop to ensure input is valid
        // Prompt user to input wall's width
      
        do {
        System.out.println("Enter wall width (feet): ");
        wallWidth = scnr.nextDouble();
        } while (wallWidth <= 0);
      
        // Calculate and output wall area
        wallArea = wallHeight * wallWidth;
        System.out.println("Wall area: " + wallArea + " square feet");

        // Calculate and output the amount of paint (in gallons) needed to paint the wall
        gallonsPaintNeeded = wallArea/squareFeetPerGallons;
        System.out.println("Paint needed: " + gallonsPaintNeeded + " gallons");

    }
}

Answer 1

The modified program

import java.util.Scanner;

public class Main {

public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
double wallHeight = 0.0;
double wallWidth = 0.0;
double wallArea = 0.0;
double gallonsPaintNeeded = 0.0;
  
final double squareFeetPerGallons = 350.0;
  
// Implement a do-while loop to ensure input is valid
// Prompt user to input wall's height
  
//Do/While loop examples in 3.18 of Zybooks
  
do {
System.out.println("Enter wall height (feet): ");
try{
wallHeight = scnr.nextDouble();
} catch(Exception e) {
System.out.println("Please enter wall height in number format");
scnr.next(); // absorb the enter key to avoid the infinite loop.
}
} while ((wallHeight <= 0));
  

// Implement a do-while loop to ensure input is valid
// Prompt user to input wall's width
  
do {
System.out.println("Enter wall width (feet): ");
try {
wallWidth = scnr.nextDouble();
}catch(Exception e) {
System.out.println("Please enter wall width in number format ");
scnr.next(); // absorb the enter key to avoid the infinite loop.
}
} while (wallWidth <= 0);
  
// Calculate and output wall area
wallArea = wallHeight * wallWidth;
System.out.println("Wall area: " + wallArea + " square feet");

// Calculate and output the amount of paint (in gallons) needed to paint the wall
gallonsPaintNeeded = wallArea/squareFeetPerGallons;
System.out.println("Paint needed: " + gallonsPaintNeeded + " gallons");

}
}

the sample output:

42 Enter wall height (feet): thirty Please enter wall height in number format Enter wall height (feet): 30 Enter wall width (feet): 25.0 Wall area: 750.0 square feet Paint needed: 2.142857142857143 gallons ... Program finished with exit code o Press ENTER to exit console.