How do I make the code repeat after the exception is executed?

Question

I know this particular exercise has been posted before but none of the answers I find do what I want this to do. I want the code to throw the exception one time if a string is entered such as "twenty". Then I want the code to repeat without terminating. Currently, if "twenty" is entered I get (code below) but I want it to end after the first "Invalid Entry" and repeat.

Enter wall height (feet): 
twenty
Invalid Entry
Enter wall width (feet): 
Invalid Entry
Wall area: 0.0 square feet
Paint needed: 0.0 gallons

import java.util.Scanner;
import java.util.InputMismatchException;

public class Paint1 {

    public static void main(String[] args)throws Exception {
        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{
            try {
               System.out.println("Enter wall height (feet): ");
               wallHeight = scnr.nextDouble();
               if (wallHeight < 0.0) {
                   throw new InputMismatchException();
               }
            }
            catch (InputMismatchException ex){
                System.out.println("Invalid Entry");
               }
        }while (wallHeight != 0.0);
         
        // Implement a do-while loop to ensure input is valid
        // Prompt user to input wall's width
        do{
            try {
               System.out.println("Enter wall width (feet): ");
               wallWidth = scnr.nextDouble();
               if (wallWidth < 0.0) {
                   throw new InputMismatchException();
               }
               }
            catch (InputMismatchException ex){
               System.out.println("Invalid Entry");
            }
        }while (wallWidth != 0.0);
            
        // 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");
        
        if (scnr != null) {
            scnr.close();
        }
       
    

    }
}

Answer 1

You have initialized wallHeight to 0.0 . When you are giving input as "twenty" ,wallHeight is still assigned to 0.0 . You can try printing wallHeight in catch block. That's the reason while loop is breaking .

Note the changes :

while condition should be while (wallHeight == 0.0). Scanner object has to be initialized everytime you want to take input .

  do{
        try {
           System.out.println("Enter wall height (feet): ");
           
           Scanner scnr = new Scanner(System.in);
           wallHeight = scnr.nextDouble();
           if (wallHeight < 0.0) {
               throw new Exception();
           }
        }
        catch (Exception ex){
            System.out.println("Invalid Entry "+ wallHeight);
           }
    }while (wallHeight == 0.0);

Answer 2

You need to clear out the leftover carriage return in the scanner stream before asking for input again after an exception:

// Implement a do-while loop to ensure input is valid
// Prompt user to input wall's height
do{
    try {
       System.out.print("Enter wall height (feet): ");
       wallHeight = scnr.nextDouble();
       if (wallHeight < 0.0) {
         throw new InputMismatchException();
       }
    }
    catch (InputMismatchException ex){
      System.out.println("Invalid Entry");
      scnr.nextLine();
   }
}while (wallHeight == 0.0);
 
// Implement a do-while loop to ensure input is valid
// Prompt user to input wall's width
do{
  try {
    System.out.print("Enter wall width (feet): ");
    wallWidth = scnr.nextDouble();
    if (wallWidth < 0.0) {
      throw new InputMismatchException();
    }
  }
  catch (InputMismatchException ex){
    System.out.println("Invalid Entry");
    scnr.nextLine();
  }
}while (wallWidth == 0.0);

Note also that the while loop condition was changed to == instead of !=1.