java中键盘录入三个同学的姓名、语文成绩、数学成绩、英语成绩，然后按照成绩从高到低写入文本，最后从文件中把数据读取出来显示在控制台上

可以按照以下步骤实现：

1. 创建一个Student类，包含姓名和三门课成绩的属性，以及按照成绩排序的方法。

public class Student {
    private String name;
    private int chineseScore;
    private int mathScore;
    private int englishScore;

    public Student(String name, int chineseScore, int mathScore, int englishScore) {
        this.name = name;
        this.chineseScore = chineseScore;
        this.mathScore = mathScore;
        this.englishScore = englishScore;
    }

    public String getName() {
        return name;
    }

    public int getChineseScore() {
        return chineseScore;
    }

    public int getMathScore() {
        return mathScore;
    }

    public int getEnglishScore() {
        return englishScore;
    }

    public int getTotalScore() {
        return chineseScore + mathScore + englishScore;
    }

    public void sortScore() {
        int[] scores = {chineseScore, mathScore, englishScore};
        Arrays.sort(scores);
        chineseScore = scores[2];
        mathScore = scores[1];
        englishScore = scores[0];
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", chineseScore=" + chineseScore +
                ", mathScore=" + mathScore +
                ", englishScore=" + englishScore +
                '}';
    }
}

2. 在主方法中，通过Scanner类从键盘输入三个学生的信息，并创建Student对象。

public static void main(String[] args) throws IOException {
    Scanner scanner = new Scanner(System.in);

    List<Student> students = new ArrayList<>();
    for (int i = 1; i <= 3; i++) {
        System.out.println("请输入第" + i + "个学生的姓名、语文成绩、数学成绩、英语成绩：");
        String name = scanner.next();
        int chineseScore = scanner.nextInt();
        int mathScore = scanner.nextInt();
        int englishScore = scanner.nextInt();
        Student student = new Student(name, chineseScore, mathScore, englishScore);
        student.sortScore(); // 按成绩排序
        students.add(student);
    }
}

3. 将学生信息按照成绩从高到低写入文本文件。

File file = new File("students.txt");
if (!file.exists()) {
    file.createNewFile();
}
PrintWriter writer = new PrintWriter(new FileWriter(file));
for (Student student : students) {
    writer.println(student.getName() + " " + student.getChineseScore() + " " + student.getMathScore() + " " + student.getEnglishScore());
}
writer.close();

4. 从文件中读取数据，并显示在控制台上。

Scanner reader = new Scanner(file);
while (reader.hasNextLine()) {
    String line = reader.nextLine();
    String[] parts = line.split(" ");
    String name = parts[0];
    int chineseScore = Integer.parseInt(parts[1]);
    int mathScore = Integer.parseInt(parts[2]);
    int englishScore = Integer.parseInt(parts[3]);
    Student student = new Student(name, chineseScore, mathScore, englishScore);
    System.out.println(student);
}
reader.close();

完整代码如下：

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws IOException {
        Scanner scanner = new Scanner(System.in);

        List<Student> students = new ArrayList<>();
        for (int i = 1; i <= 3; i++) {
            System.out.println("请输入第" + i + "个学生的姓名、语文成绩、数学成绩、英语成绩：");
            String name = scanner.next();
            int chineseScore = scanner.nextInt();
            int mathScore = scanner.nextInt();
            int englishScore = scanner.nextInt();
            Student student = new Student(name, chineseScore, mathScore, englishScore);
            student.sortScore(); // 按成绩排序
            students.add(student);
        }

        File file = new File("students.txt");
        if (!file.exists()) {
            file.createNewFile();
        }
        PrintWriter writer = new PrintWriter(new FileWriter(file));
        for (Student student : students) {
            writer.println(student.getName() + " " + student.getChineseScore() + " " + student.getMathScore() + " " + student.getEnglishScore());
        }
        writer.close();

        Scanner reader = new Scanner(file);
        while (reader.hasNextLine()) {
            String line = reader.nextLine();
            String[] parts = line.split(" ");
            String name = parts[0];
            int chineseScore = Integer.parseInt(parts[1]);
            int mathScore = Integer.parseInt(parts[2]);
            int englishScore = Integer.parseInt(parts[3]);
            Student student = new Student(name, chineseScore, mathScore, englishScore);
            System.out.println(student);
        }
        reader.close();
    }
}

class Student {
    private String name;
    private int chineseScore;
    private int mathScore;
    private int englishScore;

    public Student(String name, int chineseScore, int mathScore, int englishScore) {
        this.name = name;
        this.chineseScore = chineseScore;
        this.mathScore = mathScore;
        this.englishScore = englishScore;
    }

    public String getName() {
        return name;
    }

    public int getChineseScore() {
        return chineseScore;
    }

    public int getMathScore() {
        return mathScore;
    }

    public int getEnglishScore() {
        return englishScore;
    }

    public int getTotalScore() {
        return chineseScore + mathScore + englishScore;
    }

    public void sortScore() {
        int[] scores = {chineseScore, mathScore, englishScore};
        Arrays.sort(scores);
        chineseScore = scores[2];
        mathScore = scores[1];
        englishScore = scores[0];
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", chineseScore=" + chineseScore +
                ", mathScore=" + mathScore +
                ", englishScore=" + englishScore +
                '}';
    }
}