英文:
Don't know how to fix: error: incompatible types: possible lossy conversion from double to int
问题
import java.util.Scanner;import java.lang.Math;public class PaintEstimator {public static void main(String[] args) {Scanner scnr = new Scanner(System.in);double wallHeight;double wallWidth;double wallArea;System.out.println("Enter wall height (feet): ");wallHeight = scnr.nextDouble();System.out.println(wallHeight);wallWidth = scnr.nextDouble();System.out.println("Enter wall width (feet): ");System.out.println(wallWidth);wallArea = wallHeight * wallWidth;System.out.println("Wall area: " + (wallArea) + " square feet");double paintNeeded;int cansNeeded;final double squareFeetPerGallons;final double gallonsPerCan;squareFeetPerGallons = 350.0;gallonsPerCan = 1.0;System.out.print("Paint needed: ");paintNeeded = wallArea / squareFeetPerGallons;System.out.print(paintNeeded);System.out.println(" gallons");cansNeeded = (int) Math.ceil(paintNeeded / gallonsPerCan); // Fixed line 34System.out.print("Cans needed: ");System.out.print(cansNeeded);System.out.println(" can(s)");}}
英文:
I can't figure out what is wrong on line 34 and I need help fixing it. I don't know if I incorrectly input something or if I need to convert something.
import java.util.Scanner;import java.lang.Math;public class PaintEstimator {public static void main(String[] args) {Scanner scnr = new Scanner(System.in);double wallHeight;double wallWidth;double wallArea;System.out.println("Enter wall height (feet): ");wallHeight = scnr.nextDouble();System.out.println(wallHeight);wallWidth = scnr.nextDouble();System.out.println("Enter wall width (feet): ");System.out.println(wallWidth);wallArea = wallHeight * wallWidth;System.out.println("Wall area: " + (wallArea) + " square feet");double paintNeeded;int cansNeeded;final double squareFeetPerGallons;final double gallonsPerCan;squareFeetPerGallons = 350.0;gallonsPerCan = 1.0;System.out.print("Paint needed: ");paintNeeded = wallArea / squareFeetPerGallons;System.out.print(paintNeeded);System.out.println(" gallons");cansNeeded = paintNeeded / gallonsPerCan;System.out.print("Cans needed: ");System.out.print(cansNeeded);System.out.println(" can(s)");
}
}
答案1
得分: 2
整数没有小数点，不同于会有小数点的双精度数（doubles）。
你只能将整数赋值给整型变量（int），不能赋值给双精度数（double）等。
在你的情况下，你可能希望将 cansNeeded 定义为双精度数（double）（因为其他每个变量都是双精度数）。应该像这样：
double cansNeeded = paintNeeded / gallonsPerCan
然后你可以根据需要处理结果（向上取整、向下取整等）。这样更精确。
要向上取整，使用 Math.ceil(cansNeeded)。要向下取整，使用 Math.floor(cansNeeded)。
英文:
Integers don't have decimal points, unlike doubles, which do.
You can only assign an integer to an int, not a double etc,.
In your case, you probably want to define cansNeeded as a double (every single other variable is a double). It should look like this:
double cansNeeded = paintNeeded / gallonsPerCan
Then you can deal with the result accordingly (round up, round down etc,.). This is more precise.
To round up, use Math.ceil(cansNeeded). To round down, use Math.floor(cansNeeded).
答案2
得分: 1
将双精度数相除的结果是一个双精度数，无法赋值给整型。在您的情况下，您可能想使用 Math.ceil，然后转换为 int。
cansNeeded = (int) Math.ceil(paintNeeded / gallonsPerCan);
英文:
The result of dividing doubles is a double, which can't be assigned to an int. In your case, you probably want to use Math.ceil and then cast to int.
cansNeeded = (int) Math.ceil(paintNeeded / gallonsPerCan);
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