Question

我已经编写了这段代码，但是，每次我输入一个十进制值时，它都不起作用。即使输入十进制值，如何使此代码正常工作？例如，如果我输入值7.5，则应显示“运费为$ 9.45”

    import java.util.Scanner;

public class IfElse {
  public static void main(String[] args) {
    int marksObtained;

    Scanner input = new Scanner(System.in);

    System.out.println("Please enter a package weight in pounds:");

    marksObtained = input.nextInt();

    if (marksObtained>20)
        {
            System.out.println("The package is too heavy to be shipped");
        }
        else if (marksObtained>10)
        {
            System.out.println("The shipping cost is $12.50");
        }
            else if (marksObtained>3)
        {
            System.out.println("The shipping cost is $9.45");
        }
            else if (marksObtained>1)
        {
            System.out.println("The shipping cost is $4.95");
        }
            else if (marksObtained>0)
        {
            System.out.println("The shipping cost is $2.95");
        }
        else if (marksObtained<0)
        {
            System.out.println("The weight must be greater than zero");
        }
  }
}

Answer 1

您可以使用1 + 2 = 3 2 + 2 = 4 3 + 0 = 3 4 + 2 = 6或nextFloat

nextDouble

使用Scanner s = new Scanner (System.in); float a = s.nextFloat (); System.out.println(a);将期望输入一个int值，如果未输入nextInt，则会抛出一个java.util.InputMismatchException

Answer 2

查看用于读取输入的代码：

int marksObtained;`enter code here`
marksObtained = input.nextInt();

这里的关键是要了解int只能代表整数值，不能代表小数。对于小数，您需要使用双精度或浮点型。例如：

double marksObtained = input.nextDouble();

我建议您回顾一下Java支持的基本数据类型。您还应该熟悉the documentation for the Scanner class以及标准Java API的其余文档。

Answer 3

nextInt()仅适用于整数。使用nextDouble()

Answer 4

使用如下的nextDouble方法

public static void main(String[] args) {
    double marksObtained;

    System.out.println("Please enter a package weight in pounds:");
    Scanner input = new Scanner(System.in);
    marksObtained = input.nextDouble();
    input.close();

    if (marksObtained > 20) {
        System.out.println("The package is too heavy to be shipped");
    } else if (marksObtained > 10) {
        System.out.println("The shipping cost is $12.50");
    } else if (marksObtained > 3) {
        System.out.println("The shipping cost is $9.45");
    } else if (marksObtained > 1) {
        System.out.println("The shipping cost is $4.95");
    } else if (marksObtained > 0) {
        System.out.println("The shipping cost is $2.95");
    } else if (marksObtained < 0) {
        System.out.println("The weight must be greater than zero");
    }
}

然后关闭扫描仪，这是个好习惯。

如何使小数输入有效？

4 个答案: