读取TXT文件时遭遇InputMismatchException问题求助

我编写了一个Java程序，预期实现读取TXT文件、执行计算逻辑后输出至另一个文件的功能，但运行时出现InputMismatchException，无法定位问题根源。尝试过类型转换、调整输入文件字段顺序，问题仍未解决，恳请帮忙排查。

原始代码 #

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Create an ArrayList to store the students
        ArrayList<Student> studentList = new ArrayList<>();

        // Read data from input file and create Student objects
        try {
            Scanner input = new Scanner(new File("C:\\Users\\BP\\IdeaProjects\\Input.txt"));
            while (input.hasNext()) {
                String SID = input.next();
                int S1 = input.nextInt();
                int S2 = input.nextInt();
                int S3 = input.nextInt();
                String name = input.next();
                int totalHr = input.nextInt();
                double GPA = input.nextDouble();


                Student student = new Student(SID, name, S1, S2, S3, totalHr, GPA);
                studentList.add(student);
            }
            input.close();
        } catch (FileNotFoundException e) {
            System.err.println("Input file not found.");
            System.exit(1);
        }

        // Calculate the percentage score and assign letter grades for each student
        for (Student student : studentList) {
            student.calculatePercentageScore();
            student.calculateLetterGrade();
        }

        // Print student information including % score and grades
        for (Student student : studentList) {
            student.printStudentInfo();
        }

        // Delete students with specified IDs
        deleteStudent(studentList, "42P4");
        deleteStudent(studentList, "45A3");

        // List the ArrayList after deleting students
        System.out.println("\nAfter deleting students:");
        for (Student student : studentList) {
            student.printStudentInfo();
        }

        // Add new students to the ArrayList
        Student student1 = new Student("67T4", "Clouse B",80, 75, 98,  102,  3.65);
        Student student2 = new Student("45P5", "Garrison J",75, 78, 72,  39,  1.85);
        Student student3 = new Student("89P0", "Singer A",85, 95, 99,  130, 3.87);


        studentList.add(student1);
        studentList.add(student2);
        studentList.add(student3);

        // Calculate grades and sort the ArrayList by % score (lower to higher)
        bubbleSort(studentList);

        // Print the sorted ArrayList
        System.out.println("\nAfter sorting by % score (lower to higher):");
        for (Student student : studentList) {
            student.printStudentInfo();
        }
    }

    // Function to delete a student from the ArrayList by StudentID
    public static void deleteStudent(ArrayList<Student> studentList, String studentID) {
        for (int i = 0; i < studentList.size(); i++) {
            Student student = studentList.get(i);
            if (student.getStudentID().equals(studentID)) {
                studentList.remove(i);
                System.out.println("Student with ID " + studentID + " has been deleted.");
                break; // No need to continue searching
            }
        }
    }

    // Function to sort the ArrayList by % score (lower to higher)
    public static void bubbleSort(ArrayList<Student> studentList) {
        int n = studentList.size();
        boolean swapped;
        do {
            swapped = false;
            for (int i = 0; i < n - 1; i++) {
                if (studentList.get(i).getPercentageScore() < studentList.get(i + 1).getPercentageScore()) {
                    // Swap the students
                    Student temp = studentList.get(i);
                    studentList.set(i, studentList.get(i + 1));
                    studentList.set(i + 1, temp);
                    swapped = true;
                }
            }
        } while (swapped);
    }
}
class Student {
    private String studentID;
    private int test1, test2, test3;
    private String name;
    private int percentageScore;
    private char letterGrade;
    private int totalHr;
    private double GPA;


    public Student( String studentID, String name,int test1, int test2, int test3, int totalHour, double GPA) {
        this.test1 = test1;
        this.test2 = test2;
        this.test3 = test3;
        this.studentID = studentID;
        this.name = name;
        this.totalHr=totalHr;
        this.GPA=GPA;
    }

    public void calculatePercentageScore() {
        percentageScore = (int)((test1 + test2 + test3) / 3.0);
    }
    public void calclateClass() {
        if(totalHr >= 1 && totalHr <=30) {

        }
    }

    public void calculateLetterGrade() {
        if (percentageScore >= 90) {
            letterGrade = 'A';
        } else if (percentageScore >= 80) {
            letterGrade = 'B';
        } else if (percentageScore >= 70) {
            letterGrade = 'C';
        } else if (percentageScore >= 60) {
            letterGrade = 'D';
        } else {
            letterGrade = 'F';
        }
    }

    public void printStudentInfo() {
        System.out.println("Student ID: " + studentID);
        System.out.println("Name: " + name);
        System.out.println("Test 1: " + test1 + ", Test 2: " + test2 + ", Test 3: " + test3);
        System.out.println("Percentage Score: " + percentageScore);
        System.out.println("Letter Grade: " + letterGrade);
        System.out.println("Total hours: " +totalHr);
        System.out.println("GPA: " + GPA);
    }

    public String getStudentID() {
        return studentID;
    }

    public int getPercentageScore() {
        return percentageScore;
    }
}

输入文件内容 #

Student ID  Student Name    Test 1  Test 2  Test 3  Total Hr    GPA
    45A3        Jones_H_A   86  88  95  98      3.42
    34K5        Horner_M    67  75  23  17      1.95
    56J8        Gach_T_A    75  85  90  60      3.75
    34U8        Hunter_C    100 50  75  75      2.60
    42P4        Hinrichs_S  85  75  65  52      3.29
    78T6        Johnson_K   80  78  89  15      2.00
    44L2        Levitte_H   56  66  99  100     2.35
    88I9        Garner_J    95  92  98  110     3.89

问题根源与修复方案 #

1. 字段读取顺序与输入文件完全不匹配 #

代码中读取顺序为：SID → 测试1 → 测试2 → 测试3 → 姓名 → 总学时 → GPA，但输入文件实际顺序是：Student ID → 姓名 → 测试1 → 测试2 → 测试3 → 总学时 → GPA。当代码尝试用input.nextInt()读取姓名字段时，自然抛出类型不匹配异常。

修复：调整读取顺序与输入文件一致，或读取整行后拆分字段（更鲁棒）。

2. 未跳过文件表头 #

输入文件第一行是表头文本，代码直接开始读取，会把"Student"当作学生ID，后续尝试读取数字时必然失败。

修复：调用input.nextLine()跳过表头行。

3. Student构造函数赋值错误 #

构造函数中this.totalHr=totalHr;是将成员变量赋值给自己，正确写法应为this.totalHr=totalHour;，否则totalHr始终为默认值0。

修复：修正构造函数的赋值语句。

4. 冒泡排序逻辑颠倒 #

代码中判断条件为studentList.get(i).getPercentageScore() < studentList.get(i + 1).getPercentageScore()时交换，实际会生成降序列表，但注释要求按升序排列。

修复：将判断条件改为studentList.get(i).getPercentageScore() > studentList.get(i + 1).getPercentageScore()。

修正后的完整代码 #

import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        ArrayList<Student> studentList = new ArrayList<>();

        try {
            Scanner input = new Scanner(new File("C:\\Users\\BP\\IdeaProjects\\Input.txt"));
            // 跳过表头行
            input.nextLine();
            
            while (input.hasNextLine()) {
                String line = input.nextLine().trim();
                // 跳过空行
                if (line.isEmpty()) continue;
                // 按任意空白字符拆分字段
                String[] fields = line.split("\\s+");
                
                // 匹配输入文件顺序读取字段
                String sid = fields[0];
                String name = fields[1];
                int test1 = Integer.parseInt(fields[2]);
                int test2 = Integer.parseInt(fields[3]);
                int test3 = Integer.parseInt(fields[4]);
                int totalHr = Integer.parseInt(fields[5]);
                double gpa = Double.parseDouble(fields[6]);

                Student student = new Student(sid, name, test1, test2, test3, totalHr, gpa);
                studentList.add(student);
            }
            input.close();
        } catch (FileNotFoundException e) {
            System.err.println("输入文件未找到");
            System.exit(1);
        } catch (NumberFormatException e) {
            System.err.println("输入文件数据格式错误：" + e.getMessage());
            e.printStackTrace();
        }

        // 计算成绩与等级
        for (Student student : studentList) {
            student.calculatePercentageScore();
            student.calculateLetterGrade();
        }

        // 打印初始列表
        System.out.println("=== 初始学生列表 ===");
        for (Student student : studentList) {
            student.printStudentInfo();
        }

        // 删除指定学生
        deleteStudent(studentList, "42P4");
        deleteStudent(studentList, "45A3");

        System.out.println("\n=== 删除指定学生后 ===");
        for (Student student : studentList) {
            student.printStudentInfo();
        }

        // 添加新学生
        Student student1 = new Student("67T4", "Clouse_B", 80, 75, 98, 102, 3.65);
        Student student2 = new Student("45P5", "Garrison_J", 75, 78, 72, 39, 1.85);
        Student student3 = new Student("89P0", "Singer_A", 85, 95, 99, 130, 3.87);

        studentList.add(student1);
        studentList.add(student2);
        studentList.add(student3);

        // 升序排序
        bubbleSort(studentList);

        System.out.println("\n=== 按百分比成绩升序排序后 ===");
        for (Student student : studentList) {
            student.printStudentInfo();
        }
    }

    // 使用Iterator删除元素，避免索引异常
    public static void deleteStudent(ArrayList<Student> studentList, String studentID) {
        Iterator<Student> iterator = studentList.iterator();
        while (iterator.hasNext()) {
            Student student = iterator.next();
            if (student.getStudentID().equals(studentID)) {
                iterator.remove();
                System.out.println("已删除ID为 " + studentID + " 的学生");
                break;
            }
        }
    }

    // 修正为升序排序
    public static void bubbleSort(ArrayList<Student> studentList) {
        int n = studentList.size();
        boolean swapped;
        do {
            swapped = false;
            for (int i = 0; i < n - 1; i++) {
                if (studentList.get(i).getPercentageScore() > studentList.get(i + 1).getPercentageScore()) {
                    Student temp = studentList.get(i);
                    studentList.set(i, studentList.get(i + 1));
                    studentList.set(i + 1, temp);
                    swapped = true;
                }
            }
        } while (swapped);
    }
}

class Student {
    private String studentID;
    private int test1, test2, test3;
    private String name;
    private int percentageScore;
    private char letterGrade;
    private int totalHr;
    private double GPA;

    // 修正构造函数赋值错误
    public Student(String studentID, String name, int test1, int test2, int test3, int totalHour, double GPA) {
        this.test1 = test1;
        this.test2 = test2;
        this.test3 = test3;
        this.studentID = studentID;
        this.name = name;
        this.totalHr = totalHour;
        this.GPA = GPA;
    }

    public void calculatePercentageScore() {
        percentageScore = (int) ((test1 + test2 + test3) / 3.0);
    }

    public void calculateLetterGrade() {
        if (percentageScore >= 90) {
            letterGrade = 'A';
        } else if (percentageScore >= 80) {
            letterGrade = 'B';
        } else if (percentageScore >= 70) {
            letterGrade = 'C';
        } else if (percentageScore >= 60) {
            letterGrade = 'D';
        } else {
            letterGrade = 'F';
        }
    }

    public void printStudentInfo() {
        System.out.println("学生ID: " + studentID);
        System.out.println("姓名: " + name);
        System.out.println("测试1: " + test1 + ", 测试2: " + test2 + ", 测试3: " + test3);
        System.out.println("百分比成绩: " + percentageScore);
        System.out.println("等级: " + letterGrade);
        System.out.println("总学时: " + totalHr);
        System.out.println("GPA: " + GPA);
        System.out.println("---------------------------");
    }

    public String getStudentID() {
        return studentID;
    }

    public int getPercentageScore() {
        return percentageScore;
    }
}

内容的提问来源于stack exchange，提问作者Bethane