Question

import java.util.Scanner;
import java.text.DecimalFormat;

public class palomba2 {

    public static void main(String args[]) {

        Scanner keyboard = new Scanner(System.in);
        //allows input to be read
        // VOLUME OF A PRISM

        int prLngth, prWdth, prHght, prVol;

        System.out.print("Enter the length of the prism in feet: ");
        prLngth = keyboard.nextInt();

        System.out.print("Enter the width of the prism in feet: ");
        prWdth = keyboard.nextInt();

        System.out.print("Enter the height of the prism in feet: ");
        prHght = keyboard.nextInt();

        prVol = prLngth * prWdth * prHght;

        System.out.print("The volume of the prism is " + prVol);
        System.out.print(" feet.");
        System.out.println("");
        System.out.println("");
        // AREA/CIRCUMFERENCE OF A CIRCLE

        DecimalFormat format = new DecimalFormat("0.##");

        double radius, circ, area;

        System.out.print("Enter the radius of a circle rounded to the nearest hundreth: ");
        radius = keyboard.nextInt();

        circ = 2 * radius * 3.14159265358979;
        area = radius * radius * 3.14159265358979;

        System.out.print("The circumference of the circle is " + format.format(circ));
        System.out.print("units.");
        System.out.print("The area of the circle is " + format.format(area));
        System.out.print("units.");
    }
}

我的代码中的所有内容都会起作用，直到我输入圆的半径为止。输入半径后，它会出现错误消息。

 Enter the radius of a circle rounded to the nearest hundreth: 2.12

 Exception in thread "main" java.util.InputMismatchException
     at java.base/java.util.Scanner.throwFor(Scanner.java:860)
     at java.base/java.util.Scanner.next(Scanner.java:1497)
     at java.base/java.util.Scanner.nextInt(Scanner.java:2161)
     at java.base/java.util.Scanner.nextInt(Scanner.java:2115)
     at palomba2.main(palomba2.java:52)

Answer 1

您键入了一个双变量2.12，但尝试将其读作int：输入不匹配 - ＆gt; InputMismatchException

此外，变量radius的类型为double，因此您无法为其赋予int值（您也需要：

radius = keyboard.nextDouble();

但更好的方法是使用radius = Double.parseDouble(keyboard.nextLine())来使用返回字符（int也是如此：int val = Integer.parseInt(keyboard.nextLine())

Answer 2

您只需要更改：

radius = keyboard.nextInt();

为：

radius = keyboard.nextDouble();

因为变量radius被声明为double 它应该是这样的：

double radius, circ, area;
System.out.print("Enter the radius of a circle rounded to the nearest hundreth: ");
radius = keyboard.nextDouble();

线程“main”中的异常java.util.InputMismatchException使用Double

2 个答案: