java这个错误怎么解决？

需要class, interface或enum 锘縤mport java.io.*;

import java.io.*;
import java.text.DecimalFormat;
import java.util.*;

public class Test3 {

public static void main(String[] args) {

    File in = new File("C:/student.csv");

    FileWriter fw = null;
    BufferedReader br = null;

    if (!in.exists()) {
        System.out.println("");
        return;
    }

    try {

        br = new BufferedReader(new FileReader(in));

        String temp;
        List<Student> list = new ArrayList<Student>();

        while ((temp = br.readLine()) != null) {

            String[] data = temp.split(",");

            Student st = new Student();
            st.setStudNo(data[0]); 
            st.setName(data[1]);
            st.setMathScore(Double.parseDouble(data[2]));
            st.setEnglishScore(Double.parseDouble(data[3]));
            st.setComputerScore(Double.parseDouble(data[4]));

            list.add(st);
        }

        br.close();

        // 降序排序
        Collections.sort(list, Collections.reverseOrder());

        fw = new FileWriter("C:/student2.csv");

        DecimalFormat df = new DecimalFormat("##0.##");
        for (Student s : list) {
            fw.write(s.getStudNo());
            fw.write(",");
            fw.write(s.getName());
            fw.write(",");
            fw.write(df.format(s.getMathScore()));
            fw.write(",");
            fw.write(df.format(s.getEnglishScore()));
            fw.write(",");
            fw.write(df.format(s.getComputerScore()));
            fw.write(",");
            fw.write(df.format(s.getAvgScore()));
            fw.write("\n");
        }

        System.out.println("output OK");

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (br != null) {
                br.close();
            }
            if (fw != null) {
                fw.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

}
class Student{
String Name;
String studno;
Double mathScore;
Double englishScore;
Double computerScore;
Double avgScore;

void setName(String sName){
Name=sName;
}
void setStudNo(String sNo){
studno=sNo;
}
void setMathScore(Double dmathScore){
mathScore=dmathScore;
}
void setEnglishScore(Double denglishScore){
englishScore=denglishScore;
}
void setComputerScore(Double dcomputerScore){
computerScore=dcomputerScore;
}
void setavgScore(){
avgScore=(mathScore+englishScore+computerScore)/3;
}

String getName(){
return Name;
}
String getStudNo(){
return studno;
}
Double getMathScore(){
return mathScore;
}
Double getEnglishScore(){
return englishScore;
}
Double getComputerScore(){
return computerScore;
}
Double getAvgScore(){
return avgScore;
}

}

不明白你说的错在哪，把下面对应的改掉

 // 降序排序
        Collections.sort(list, new Comparator<Student>(){
                @Override
                public int compare(Student s1,Student s2){
                    return s1.getAvgScore() == s2.getAvgScore() ? 0 : (s1.getAvgScore() > s2.getAvgScore() ? -1: 1);
                }
            }
        );

鄙人觉得可能是编码问题

控制台报错内容是啥？？

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把运行结果发出来看看