#Test2.java

/*
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 */
package bt1071;

/**
 *
 * @author Diep.Tran
 */
public class Test2 {
    static Thread t1, t2 = null;
    
    public static void main(String[] args) {
        //Main Thread -> luong chinh
        System.out.println("Step 1");
        
        
        t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 10; i++) {
                    System.out.println("Step 2 - " + i);
                    if(i == 5) {
                        t2.start();
                    }
                }
            }
        });
        
        t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i = 0; i < 10; i++) {
                    System.out.println("Step 3 - " + i);
//                    t1.stop();
                }
            }
        });
//        t2.start();//T2 -> chay => T2 & Main
        t1.start();//T1 -> chay => T1 & Main & T2
        
        System.out.println("Finish");
    }
}

#Test.java

/*
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 */
package bt1071;

import aptech.java2.lession3.FileInOutStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author Diep.Tran
 */
public class Test {
    public static void main(String[] args) {
//        writeData();
        
        readData();
    }
    
    static void readData() {
        List<Student> studentList = new ArrayList<>();
        
        FileInputStream fis = null;
        ObjectInputStream ois = null;
        
        try {
            fis = new FileInputStream("student.dat");
            ois = new ObjectInputStream(fis);
            
//            studentList = (List<Student>) ois.readObject();
            
            while(true) {
                Object obj = ois.readObject();
                if(obj != null) {
                   studentList.add((Student) obj); 
                } else {
                    break;
                }
            }
        } catch (FileNotFoundException ex) {
//            Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
//            Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
        } catch (ClassNotFoundException ex) {
//            Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            try {
                fis.close();
            } catch (IOException ex) {
                Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
            }
            try {
                ois.close();
            } catch (IOException ex) {
                Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
        
        for (Student student : studentList) {
            student.display();
        }
    }
    
    static void writeData() {
        List<Student> studentList = new ArrayList<>();
        
        Student std1 = new Student();
        std1.input();
        studentList.add(std1);
        
        Student std2 = new Student();
        std2.input();
        studentList.add(std2);
        
        //Luu du lieu vao FILE.
        FileOutputStream fos = null;
        ObjectOutputStream oos = null;
        
        try {
            fos = new FileOutputStream("student.dat");
            
            oos = new ObjectOutputStream(fos);
            
            //Lam viec voi List
//            oos.writeObject(studentList);
            
            //Lam viec voi Object
            for (Student student : studentList) {
                oos.writeObject(student);
            }
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            try {
                fos.close();
            } catch (IOException ex) {
                Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
            }
            try {
                oos.close();
            } catch (IOException ex) {
                Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
            }
        }
    }
}

#Student.java

/*
 * 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 bt1071;

import java.io.Serializable;
import java.util.Scanner;

/**
 *
 * @author Diep.Tran
 */
public class Student implements Serializable{
    //id: tu tang -> giai phap la gi?
    static int count = 0;
    
    int id = 0, age;
    String name, address;
    float gpa;

    public Student() {
        id = ++count;
    }

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

    public int getId() {
        return id;
    }

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

    public int getAge() {
        return age;
    }

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

    public String getName() {
        return name;
    }

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

    public String getAddress() {
        return address;
    }

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

    public float getGpa() {
        return gpa;
    }

    public void setGpa(float gpa) {
        this.gpa = gpa;
    }
    
    public void input() {
        Scanner abc = new Scanner(System.in);
//        System.out.println("Nhap ID: ");
//        id = Integer.parseInt(abc.nextLine());
        
        System.out.println("Nhap ten: ");
        name = abc.nextLine();
        
        System.out.println("Nhap dia chi: ");
        address = abc.nextLine();
        
        System.out.println("Nhap tuoi: ");
        age = Integer.parseInt(abc.nextLine());
        
        System.out.println("Nhap GPA: ");
        gpa = Float.parseFloat(abc.nextLine());
    }
    
    public String getFileLine() {
        return id + "," + name + "," + age + "," + address + "," + gpa + "\n";
    }
    
    public void parse(String line) {
        String[] params = line.split(",");
        
        try {
            id = Integer.parseInt(params[0]);
            name = params[1];
            age = Integer.parseInt(params[2]);
            address = params[3];
            gpa = Float.parseFloat(params[4]);
        } catch(ArrayIndexOutOfBoundsException ex) {
        } finally {
        }
    }
    
    public void display() {
        System.out.println(this);
    }

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

#Main.java

/*
 * 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 bt1071;

import aptech.java2.lession3.FileInOutStream;
import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.StandardCharsets;
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 List<Student> studentList = new ArrayList<>();
    static Scanner scan = new Scanner(System.in);
    
    public static void main(String[] args) {
        int choose;
        
        do {
            showMenu();
            choose = Integer.parseInt(scan.nextLine());
            
            switch(choose) {
                case 1:
                    inputStudent();
                    break;
                case 2:
                    editStudentById();
                    break;
                case 3:
                    deleteStudentById();
                    break;
                case 4:
                    sortStudentByGPA();
                    break;
                case 5:
                    sortStudentByName();
                    break;
                case 6:
                    displayStudent();
                    break;
                case 7:
                    saveFile();
                    break;
                case 8:
                    readFile();
                    break;
                case 9:
                    System.out.println("Thoat!!!");
                    break;
                default:
                    System.out.println("Nhap sai!!!");
                    break;
            }
        } while(choose != 9);
    }
    
    static void showMenu() {
        System.out.println("1. Them sinh vien");
        System.out.println("2. Sua sinh vien theo id");
        System.out.println("3. Xoa sinh vien theo id");
        System.out.println("4. Sap xep theo GPA");
        System.out.println("5. Sap xep theo ten");
        System.out.println("6. Hien thi thong tin sinh vien");
        System.out.println("7. Luu vao file student.txt");
        System.out.println("8. Doc noi dung sinh vien tu student.txt");
        System.out.println("9. Thoat");
        System.out.println("Chon: ");
    }

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

    private static void editStudentById() {
        System.out.println("Nhap id sinh vien can sua: ");
        int id = Integer.parseInt(scan.nextLine());
        
        for (Student student : studentList) {
            if(student.getId() == id) {
                student.input();
                break;
            }
        }
    }

    private static void deleteStudentById() {
        System.out.println("Nhap id sinh vien can xoa: ");
        int id = Integer.parseInt(scan.nextLine());
        
        for (Student student : studentList) {
            if(student.getId() == id) {
                studentList.remove(student);
                break;
            }
        }
    }

    private static void sortStudentByGPA() {
        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 sortStudentByName() {
        Collections.sort(studentList, new Comparator<Student>() {
            @Override
            public int compare(Student o1, Student o2) {
                return o1.getName().compareToIgnoreCase(o2.getName());
                //Z-A (A-Z: them dau - truoc)
            }
        });
    }

    private static void displayStudent() {
        for (Student student : studentList) {
            student.display();
        }
    }

    private static void saveFile() {
        //Luu file
        System.out.println("Bat dau luu:");
        FileOutputStream fos = null;
        
        try {
            fos = new FileOutputStream("student.txt", true);
            
            //luu du lieu
            for (Student student : studentList) {
                String line = student.getFileLine();
                //chuyen string to byte[]
                byte[] b = line.getBytes("utf8");
                //Save
                fos.write(b);
            }
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        } 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);
        } finally {
            if(fos != null) {
                try {
                    fos.close();
                } catch (IOException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
    }

    private static void readFile() {
        FileInputStream fis = null;
        InputStreamReader reader = null;
        BufferedReader bufferedReader = null;
        
        try {
            fis = new FileInputStream("student.txt");
            
            reader = new InputStreamReader(fis, StandardCharsets.UTF_8);
            
            bufferedReader = new BufferedReader(reader);
            
            String line = null;
            
            while((line = bufferedReader.readLine()) != null) {
                if(line.isEmpty()) {
                    continue;
                }
                Student std = new Student();
                std.parse(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 {
            if(fis != null) {
                try {
                    fis.close();
                } catch (IOException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
            
            if(reader != null) {
                try {
                    reader.close();
                } catch (IOException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
            
            if(bufferedReader != null) {
                try {
                    bufferedReader.close();
                } catch (IOException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
        
    }
}