我需要创建程序来为用户提供生成报告的能力，该报告按乡镇名称的字母顺序或乡镇平方英里的大小顺序显示。

但是当我使用代码运行文本文件时收到错误消息。

如果没有文本文件，我的代码可以工作，但是当我尝试将文本文件与代码一起使用时，我会收到此错误。

Exception in thread "main" java.lang.NumberFormatException: For input string: ""
   at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)
   at java.base/java.lang.Integer.parseInt(Integer.java:678)
   at java.base/java.lang.Integer.parseInt(Integer.java:786)
   at Main.main(Mice.java:76)

我的代码：

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;


// create mice class

class Mice {

    private final double micepopulation;
    private final int sizetown;
    private final String town;


    // =-=-=-=-=-=-=-=-=--==-=


    public Mice(double population, int sizetown, String town) {

        this.town = town;
        this.micepopulation = population;
        this.sizetown = sizetown;
    }


// --==--=-=-=-=-=-=-=-=-=--=

    public String miceelseif() {
        if (micepopulation > 75) {
            return "Blue";
        } else if (micepopulation > 65) {
            return "Green";
        } else if (micepopulation > 50) {
            return "Yellow";
        } else if (micepopulation > 35) {
            return "Orange";
        } else {
            return "Red";
        }

        // -=-=-=-=-=-=-=-=-=-=-=-=-
    }
    public String getTOWN() {
        return town;
    }

    public String toString() {
        return String.format("%-25s%-20.2f%-20d%-20s", town, micepopulation, sizetown, miceelseif());
    }
}


public class Main {
    public static void main(String[] args) {
        int numRecords = getNumRecords();
        String[] township = new String[numRecords];
        double[] population = new double[numRecords];
        int[] townsize = new int[numRecords];

        try {
            Scanner fileScanner = new Scanner(new File("Micepopulation.txt"));
            int index = 0;
            while (fileScanner.hasNextLine()) {
                township[index] = fileScanner.nextLine();
                String[] popTwonSizeContents = fileScanner.nextLine().trim().split("");
                population[index] = Double.parseDouble(popTwonSizeContents[0]);
                townsize[index] = Integer.parseInt(popTwonSizeContents[1]);
                // increment the index
                index++;
            }
            fileScanner.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

        Mice[] micePop = new Mice[numRecords];

        for (int index = 0; index < micePop.length; index++) {
            micePop[index] = new Mice(population[index], townsize[index], township[index]);
        }

        Scanner scanner = new Scanner(System.in);
        int choice;
        do {
            System.out.println("1: Mice by Town");
            System.out.println("2: Mice by size");
            System.out.println("3- Town name");
            System.out.println("0- Exit");
            System.out.print(" Please enter your choice: ");
            choice = scanner.nextInt();
            scanner.nextLine();

            switch (choice) {
                case 0 -> System.out.println("thank you, have a good day");
                case 1, 2 -> bytown(micePop);
                case 3 -> {
                    System.out.print("please enter town ");
                    String town = scanner.nextLine();
                    int foundIndex = townLookUp(micePop, town);
                    if (foundIndex == -1) {
                        System.out.println("no town");
                    } else {
                        System.out.printf("%-25s%-20s%-20s%-20s\n", "Town", "Mice Population", "Town Size",
                                "Alerts");
                        System.out.println(micePop[foundIndex].toString());
                    }
                }
                default -> System.out.println("Invalid choice");
            }
            System.out.println();
        } while (choice != 0);
        scanner.close();
    }

    // ==-=-=-===--==-=-=-=-=-=-=-=-=-=--==-





    private static void bytown(Mice[] micePop) {
        for (int index = 0; index < micePop.length; index++) {
            for (int innerIndex = 0; innerIndex < micePop.length - index - 1; innerIndex++) {
                if (micePop[innerIndex].getTOWN().compareTo(micePop[innerIndex + 1].getTOWN()) > 0) {
                    Mice temp = micePop[innerIndex];
                    micePop[innerIndex] = micePop[innerIndex + 1];
                    micePop[innerIndex + 1] = temp;
                }
            }
        }
        System.out.println("\nREPORT BY TOWN");
        printMicePopulation(micePop);
    }

    // -=-===-=-=-=--==-=-=--==-=-


    // =-=--=-==-=-=-=--==-=-=-=-=-=-=--==-=-=--
    private static int townLookUp(Mice[] micePop, String township) {
        for (int index = 0; index < micePop.length; index++) {
            if (micePop[index].getTOWN().equalsIgnoreCase(township)) {
                return index;
            }
        }
        return -1;
    }

    // -=-==-=-=-=--==--==-=-==-=-=-=-=-=-=--==-=-=-----=

    private static void printMicePopulation(Mice[] micePop) {
        System.out.printf("%-25s%-20s%-20s%-20s\n", "Town", "Mice Population", "Town Size", "Threat Alert");
        for (Mice mice : micePop) System.out.println(mice.toString());

    }

    // -=-==--==--==-==-=-=-===-=-=-=-=-=-=-=-

    public static int getNumRecords() {
        try {
            Scanner scanner = new Scanner(new File("Micepopulation.txt"));
            int numRecords = 0;

            while (scanner.hasNextLine()) {
                numRecords++;
                scanner.nextLine();
            }
            scanner.close();
            return numRecords / 2;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        return 0;
    }

}

我正在尝试附加的文本文件

City of Red
70.81  2137
Boro of Orange
101.77 71
Yellow City
83.13  1034
Green Town
54.79  1819
Blueville
45.71  1514
Indigo Village
4.15 1442
Violeton 
119.27 2225
Redburg
7.46 977
Orange Park
16.72  133
Yellow Falls
94.5  4556
Green Haven
326.12 1105242
Blue City
44.69 1979
Indigo Township
113.56 365
Violet Point
35.27 4161