java - 如何根据输入类型执行某些命令

Question

我设置了一个扫描仪，要求用户输入数字或输入“示例”以使用预设数字。如果他们输入一个数字，代码应该会问他们更多问题，然后进行计算。这执行得很完美。如果用户输入“EXAMPLE”，则应该将变量设置为预设数字并进行计算。输入 EXAMPLE 后，我无法使代码正常工作。我收到此错误:

Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Unknown Source)
    at java.util.Scanner.next(Unknown Source)
    at java.util.Scanner.nextFloat(Unknown Source)
    at CarPool.main(CarPool.java:22)

这是我的代码:抱歉，如果它太困惑了。

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

public class CarPool {
    public static void main(String[] args) {
        @SuppressWarnings("resource")
        Scanner input = new Scanner(System.in);
        //inputs the scanner tool

        float totaldistance;
        float MPG;
        float gasprice;
        float gasused;
        float totalpeople;
        float totalcost;
        //assigns variables

        System.out.printf("Please type the total distance (miles) you are travelling, or type EXAMPLE for an example: ");
        totaldistance = input.nextFloat();
        if (isNan(totaldistance)) { //If the user types EXAMPLE, use preset numbers
            totaldistance = 8;
            MPG = 23;
            gasprice = (float) 2.31;
            totalpeople = 4;
        }  else if (isNumeric(totaldistance)); {
            System.out.printf("Please enter the MPG of your vehicle: ");
            MPG = input.nextFloat();
            System.out.printf("Pleas enter the price of gas currently: $");
            gasprice = input.nextFloat();
            System.out.printf("Please enter how many people will be splitting the cost of gas:");
            totalpeople = input.nextFloat();
            //Prompts the user for some info that it can use for it's calculations. Sets them as floats for decimal numbers.
        }
        gasused = (totaldistance / MPG); //This finds how much gas the person is using by dividing the distance travelled by the mpg
        totalcost = gasused * gasprice; //This calculates how much you will spend by multiplying the gas you use by the price of gas, given by the user
        totalcost = totalcost / totalpeople; //splits the final cost amongst however many people are chipping in
        NumberFormat formatter = new DecimalFormat("$" + "#0.00"); //Formats the price to two decimal places
        System.out.println(formatter.format(totalcost)); //prints the final results
    }

    private static boolean isNumeric(float totaldistance) {
        return false;
    }

    private static boolean isNan(float totaldistance) {
        return false;
    }
}

我在第 22 行遇到问题。

Answer 1

显然你会得到一个不匹配的异常，因为如果用户输入示例，你正在将其读取为 float ，现在你告诉我可以将示例转换为 float 。不对吗？？

那么为什么不将输入数据作为字符串读取并检查它是否是示例，然后使用您的预设值，否则如果它 float 则相应地使用

我想你应该明白我的意思。

干杯