1.先寫一個Student類

public class Student {
    private String name;
    private int chinese;
    private int math;
    private int english;

    public Student() {
        super();
    }

    public Student(String name, int chinese, int math, int english) {
        this.name = name;
        
 
this.chinese = chinese;
        this.math = math;
        this.english = english;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getChinese() {
        return chinese;
    }

    
 
public void setChinese(int chinese) {
        this.chinese = chinese;
    }

    public int getMath() {
        return math;
    }

    public void setMath(int math) {
        this.math = math;
    }

    public int getEnglish() {
        return english;
    }

    public void setEnglish(int
 
 english) {
        this.english = english;
    }

    public int getTotal(){
        return (this.chinese + this.math + this.english);
    }

    @Override
    public String toString() {
        return "Student{" +
                "name=‘" + name + ‘\‘‘ +
                ", chinese=" + chinese +
                ", math=" + math +
                ", english=" + english +
                ‘}‘;
    }
}

2.錄入5個學生信息(姓名,語文成績,數學成績,英語成績),按照總分從高到低存入文本文件

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Comparator;
import java.util.TreeSet;

public class Demo {
    public static void main(String[] args) throws IOException {
        //創建5個學生對象
        Student s1 = new Student("孫悟空",80,80,80);
        Student s2 = new Student("豬八戒",90,90,90);
        Student s3 = new Student("玉皇大帝",100,100,100);
        Student s4 = new Student("嫦娥",100,100,100);
        Student s5 = new Student("白骨精",90,80,100);

        //按照總分從高到低存入TreeSet
        TreeSet<Student> set = new TreeSet<>(new Comparator<Student>() {
            @Override
            public int compare(Student s1, Student s2) {
                int cmp1 =   s2.getTotal() - s1.getTotal();//總分從高到低排序
                int cmp2 = cmp1 == 0 ? s2.getName().compareTo(s1.getName()) : cmp1;//保證可以出現總分相同但是名字不同的學生
                return cmp2;
            }
        });

        //將學生信息存入集合
        set.add(s1);
        set.add(s2);
        set.add(s3);
        set.add(s4);
        set.add(s5);

        //3.遍歷集合並寫入文件
        BufferedWriter writer = new BufferedWriter(new FileWriter("Day27_Thread01\\student.txt"));
        for (Student s :set) {
            StringBuilder sb = new StringBuilder("姓名：" + s.getName()  + ", 語文成績：" + s.getChinese() +
                    ", 數學成績：" + s.getMath() + ", 英語成績：" + s.getEnglish());
            writer.write(sb.toString());
            writer.newLine();
            writer.flush();
        }
        writer.close();
    }
}

3.鍵盤錄入5個學生信息(姓名,語文成績,數學成績,英語成績),按照總分從高到低存入文本文件

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Comparator;
import java.util.Scanner;
import java.util.TreeSet;

public class Demo2 {
    public static void main(String[] args) throws IOException {
        //創建TreeSet集合
        TreeSet<Student> set = new TreeSet<>(new Comparator<Student>() {
            @Override
            public int compare(Student s1, Student s2) {
                int cmp1 =   s2.getTotal() - s1.getTotal();
                int cmp2 = cmp1 == 0 ? s2.getName().compareTo(s1.getName()) : cmp1;
                return cmp2;
            }
        });

        for (int i = 0;i < 5;i++){
            //輸入學生信息
            Scanner sc = new Scanner(System.in);
            System.out.println("請輸入學生的姓名：");
            String name = sc.nextLine();
            System.out.println("請輸入該學生的語文成績：");
            int chinese = sc.nextInt();
            System.out.println("請輸入該學生的數學成績：");
            int math = sc.nextInt();
            System.out.println("請輸入該學生的英語成績：");
            int english = sc.nextInt();

            //創建學生對象並錄入信息
            Student s = new Student();
            s.setName(name);
            s.setChinese(chinese);
            s.setMath(math);
            s.setEnglish(english);

            //將學生添加到集合裏
            set.add(s);
        }

        //3.遍歷集合並寫入文件
        BufferedWriter writer = new BufferedWriter(new FileWriter("Day27_Thread01\\student.txt"));
        for (Student s :set) {
            StringBuilder sb = new StringBuilder("姓名：" + s.getName()  + ", 語文成績：" + s.getChinese() +
                    ", 數學成績：" + s.getMath() + ", 英語成績：" + s.getEnglish());
            writer.write(sb.toString());
            writer.newLine();
            writer.flush();
        }

        //關閉資源
        writer.close();
    }
}

鍵盤錄入學生信息(姓名,語文成績,數學成績,英語成績),按照總分從高到低存入文本文件