定义一个工具函数用于从文件读取所有学生信息，创建学生数组。

要求：

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public class Student {
  public static Student[] readFromFile(String path, int num) {
    // 使用FileReader读取文件，设置路径参数；
    // 使用BufferedReader对FileReader进行装饰，支持按行读取的readLine()方法
    // 循环读取每一行数据，一行代表一个学生信息：(line = br.readLine()) != null
    // 使用String.split(",")方法将每行数据分割为数组，根据索引获取对应字段值来初始化Student对象
    // 返回学生对象数组
  }
}

写法：

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public static Student[] readFromFile(String path, int num) {
       Student[] students = new Student[num];
       try (BufferedReader br = new BufferedReader(new FileReader(path))) {
           String line;
           int index = 0;
           while ((line = br.readLine()) != null && index < num) {
               // 假设每行数据格式为：name,age,grade
               String[] parts = line.split(",");
               if (parts.length == 3) {
                   String name = parts[0].trim();
                   int age = Integer.parseInt(parts[1].trim());
                   String grade = parts[2].trim();
                   students[index++] = new Student(name, age, grade);
               }
           }
       } catch (IOException e) {
           System.err.println("Error reading file: " + e.getMessage());
       }
       return students;
   }

尝试用Files和Paths读取文件，实现读取文件的功能。

要求：

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public class Student {
  public static Student[] readFromFile(String path, int num) {
    // Files.readAllLines(Paths.get(path))来读取所有行
    // for(String line : lines)来遍历List中的每一行
    // 使用String.split(",")方法将每行数据分割为数组，根据索引获取对应字段值来初始化Student对象
    // 返回学生对象数组
  }
}

写法：

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public static Student[] readFromFile(String path, int num) {
    Student[] stu = new Student[0];
  try {
    List<String> lines = Files.readAllLines(Paths.get(path));
    stu = new Student[Math.min(num,lines.size())];
    int index = 0;

    for (String line : lines) {
      if (index >= num) break;
      String[] parts = line.split(",");
      String id = parts[0];
      int scoreA = Integer.parseInt(parts[1]);
      int scoreB = Integer.parseInt(parts[2]);
      int scoreC = Integer.parseInt(parts[3]);
      stu[index] = new Student(id, scoreA, scoreB, scoreC);
      index++;
    }
  } catch (IOException e) {
    System.out.println(e);
  }
  
  return stu;
}

排序函数

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public class Student {
  public static void sortByTotalScore(Student[] s) {
    // 实现一个基于总分比较的Comparator接口
    Arrays.sort(s, c);
  }
}

附上要求的Comparator接口实现

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// Comparator 实现
   public static final Comparator<Student> c = new Comparator<Student>() {
       @Override
       public int compare(Student s1, Student s2) {
           return Double.compare(s2.getTotalScore(), s1.getTotalScore()); // 按总分从高到低排序
       }
   };

lambda表达式的简写：

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public static void sortByTotalScore(Student[] s) {
    Arrays.sort(s, Comparator.comparingInt(x -> x.totalScore()));
  }