Hướng dẫn chữa bài quản lý sinh vien + file

Link Bài Tập

Sour code

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package java2.lession3.files;

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author Diep.Tran
 */
public class Main {
    static Scanner input = new Scanner(System.in);
    
    public static void main(String[] args) {
        List<Student> studentList = new ArrayList<>();
        int choose;
        
        do {
            showMenu();
            choose = Integer.parseInt(input.nextLine());
            
            switch(choose) {
                case 1:
                    addStudent(studentList);
                    break;
                case 2:
                    editStudentById(studentList);
                    break;
                case 3:
                    deleteStudentById(studentList);
                    break;
                case 4:
                    sortStudentByGPA(studentList);
                    displayAllStudent(studentList);
                    break;
                case 5:
                    sortStudentByName(studentList);
                    displayAllStudent(studentList);
                    break;
                case 6:
                    displayAllStudent(studentList);
                    break;
                case 7:
                    saveFile(studentList);
                    break;
                case 8:
                    readFile(studentList);
                    displayAllStudent(studentList);
                    break;
                case 9:
                    System.out.println("Exit!!!");
                    break;
                default:
                    System.out.println("Input failed!!!");
                    break;
            }
        } while(choose != 9);
    }
    
    static void showMenu() {
        System.out.println("1. Add student.");
        System.out.println("2. Edit student by id.");
        System.out.println("3. Delete student by id.");
        System.out.println("4. Sort student by gpa.");
        System.out.println("5. Sort student by name.");
        System.out.println("6. Show student.");
        System.out.println("7. Lưu thông tin sv vào file student.txt");
        System.out.println("8. Đọc thông tin sv từ file student.txt và hiển thị ra màn hình");
        System.out.println("9. Exit");
        System.out.println("Choose: ");
    }

    private static void addStudent(List<Student> studentList) {
        System.out.println("Nhap so sinh vien can them: ");
        int n = Integer.parseInt(input.nextLine());
        
        for (int i = 0; i < n; i++) {
            Student std = new Student();
            //nhap thong tin sinh vien
            std.input();
            
            studentList.add(std);
        }
    }

    private static void editStudentById(List<Student> studentList) {
        System.out.println("Nhap ID sinh vien can sua thong tin: ");
        int id = Integer.parseInt(input.nextLine());
        
        //tim sinh vien
        Student stdFind = null;
        for (Student student : studentList) {
            if(student.getId() == stdFind.getId()) {
                stdFind = student;
                break;
            }
        }
        
        if(stdFind != null) {
            //edit
            stdFind.edit();
        } else {
            System.out.println("Not found");
        }
    }

    private static void deleteStudentById(List<Student> studentList) {
        System.out.println("Nhap ID sinh vien can xoa: ");
        int id = Integer.parseInt(input.nextLine());
        
        Student stdFind = null;
        for (Student student : studentList) {
            if(student.getId() == stdFind.getId()) {
                stdFind = student;
                break;
            }
        }
        
        if(stdFind != null) {
            studentList.remove(stdFind);
        } else {
            System.out.println("Not found");
        }
    }

    private static void sortStudentByGPA(List<Student> studentList) {
        Collections.sort(studentList, new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                if(o1.getGpa() > o2.getGpa()) {
                    return 1;
                }
                return -1;
            }
        });
    }

    private static void displayAllStudent(List<Student> studentList) {
        for (Student student : studentList) {
            student.display();
        }
    }

    private static void sortStudentByName(List<Student> studentList) {
        Collections.sort(studentList, new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                return o1.getName().compareToIgnoreCase(o2.getName());
            }
        });
    }

    private static void saveFile(List<Student> studentList) {
        FileOutputStream fos = null;
        BufferedOutputStream bos = null;
        try {
            String filename = "student.txt";
            fos = new FileOutputStream(filename);
            
            bos = new BufferedOutputStream(fos);
            
            //ghi du lieu vao FILE
            for (Student student : studentList) {
                String line = student.getLine();
                byte[] b;
                try {
                    b = line.getBytes("utf8");
                    bos.write(b);
                } catch (UnsupportedEncodingException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                } catch (IOException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            try {
                if(bos != null) {
                    bos.close();
                }
                if(fos != null) {
                    fos.close();
                }
            } catch (IOException ex) {
                Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }

    private static void readFile(List<Student> studentList) {
        FileReader reader = null;
        BufferedReader bufferedReader = null;
        try {
            String filename = "student.txt";
            reader = new FileReader(filename);
            
            bufferedReader = new BufferedReader(reader);
            
            //doc du lieu tu FILE
            String line = null;
            while((line = bufferedReader.readLine()) != null) {
                Student std = new Student();
                std.parseLine(line);
                
                studentList.add(std);
            }
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            try {
                if(bufferedReader != null) {
                    bufferedReader.close();
                }
                if(reader != null) {
                    reader.close();
                }
            } catch (IOException ex) {
                Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
}

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package java2.lession3.files;

import java.util.Scanner;

/**
 *
 * @author Diep.Tran
 */
public class Student {
    String name, address;
    int id;
    float gpa;
    int age;

    public Student() {
    }

    public Student(String name, int age, String address, int id, float gpa) {
        this.name = name;
        this.age = age;
        this.address = address;
        this.id = id;
        this.gpa = gpa;
    }

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public float getGpa() {
        return gpa;
    }

    public void setGpa(float gpa) {
        this.gpa = gpa;
    }
    
    public void input() {
        Scanner input = new Scanner(System.in);
        System.out.println("Nhap ID: ");
        id = Integer.parseInt(input.nextLine());
        
        edit();
    }

    public void edit() {
        Scanner input = new Scanner(System.in);
        System.out.println("Nhap ten: ");
        name = input.nextLine();
        
        System.out.println("Nhap tuoi: ");
        age = Integer.parseInt(input.nextLine());
        
        System.out.println("Nhap dia chi: ");
        address = input.nextLine();
        
        System.out.println("Nhap diem trung binh: ");
        gpa = Float.parseFloat(input.nextLine());
    }

    public void display() {
        System.out.println(this);
    }

    @Override
    public String toString() {
        return "Student{" + "name=" + name + ", address=" + address + ", id=" + id + ", gpa=" + gpa + ", age=" + age + '}';
    }

    String getLine() {
        //name, address, id, gpa, age
        return name + "," + address + "," + id + "," + gpa + "," + age + "\n";
    }

    public void parseLine(String line) {
        //remove whiteplace
        line = line.trim();
        String[] params = line.split(",");
        if(params.length < 5) {
            System.out.println("Data error");
            return;
        }
        name = params[0];
        address = params[1];
        id = Integer.parseInt(params[2]);
        gpa = Float.parseFloat(params[3]);
        age = Integer.parseInt(params[4]);
    }
}