I don't understand where does $64 comes from-CodePudding

Assume that a gallon of paint cover's about 350 square feet of wall space, ask a user to enter length, width and height. The methods should do the following:

Calculate the wall area for a room
Passes the calculated wall area to another method that calculates and returns the number of gallons of paint needed
Display the number of gallons needed
Computes the price based on a paint price $32 per gallon, assuming that the painter can buy any fraction of a gallon of paint at the same price as a whole gallon.
returns the price to the main method. The main() method displays the final price. Example: the cost to paint a 15-by-20 room with 10-foot ceilings is $64.

Here us what I did, and I'm failing to get that $64

public static void main(String[] args){

    double  l,h,w;
    Scanner sc=new Scanner(System.in);
    System.out.print("Enter the height: ");
    h=sc.nextDouble();
    System.out.print("Enter the width: ");
    w=sc.nextDouble();
    System.out.print("Enter the length: ");
    l=sc.nextDouble();
    disGallons(calArea(h, w, l));
    disPrice(price(calGallon(calArea(h, w, l))));
}

public static double calArea(double h,double w, double l){
    double area=2*((w*h) (l*w) (l*h));
    return area;
}
public static double calGallon(double area){
    double gallons= area/350;
    return gallons;
}
public static void disGallons(double gallons){
    System.out.println("Gallons needed: " gallons);
}
public static double price(double gallon){
    final double gallPrice=32;
    return (int)(gallPrice*gallon);
}
public static void disPrice(double price){
    System.out.println("Total Price is: $" price);
}

CodePudding user response：

Here's how I'd do it.

package io.duffymo;

/**
 * Size the amount of paint needed
 * @link <a href="https://stackoverflow.com/questions/72404779/i-dont-understand-where-does-64-comes-from">...</a>
 */
public class PaintSizing {

    public static final double PRICE_PER_GALLON_USD = 32.0;
    public static final double SQ_FEET_PER_GALLON = 350.0;

    public static double area(double h, double w, double l) {
        return 2.0*(w   l)*h;
    }

    public static double gallons(double area) {
        return area / SQ_FEET_PER_GALLON;
    }

    public static double price(double gallons) {
        return gallons * PRICE_PER_GALLON_USD;
    }
}

It's never too soon to learn about JUnit:

package io.duffymo;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;

public class PaintSizingTest {

    @Test
    public void testSizing() {
        // setup
        double l = 15.0;
        double w = 20.0;
        double h = 10.0;
        double expectedArea = 700.0;
        double expectedGallons = 2.0;
        double expectedPrice = 64.0;
        // exercise
        double actualArea = PaintSizing.area(h, w, l);
        double actualGallons = PaintSizing.gallons(actualArea);
        double actualPrice = PaintSizing.price(actualGallons);
        // assert
        Assertions.assertEquals(expectedArea, actualArea, 0.001);
        Assertions.assertEquals(expectedGallons, actualGallons, 0.001);
        Assertions.assertEquals(expectedPrice, actualPrice, 0.001);
    }

}