College/Lecturer Exr. 9.1

import College.*;

public class Main {
    public static void main(String[] args) throws FileNotFoundException  {
            Scanner sc = new Scanner(System.in);
        //default filename
        String fileName = "default.txt";
        System.out.println("Do you want to read information from some file? 1-yes 0-no");
        if (sc.nextInt() == 1) {
            System.out.println("Write a name of a file");
            fileName = sc.next() + ".txt";
            //Read info from file
            College read = readFromFile(fileName);
        }
        //new college
        College harvard = new College("Harvard", 20);
        //adding two lecturers
        harvard.addLecturer(new Lecturer("Bob", "magnum", 52));
        harvard.addLecturer(new Lecturer("gogo", "fistuk", 15));
        //checking sort function
        harvard.sortLecturersByLessFall();
        //prints all information about college
        System.out.println(harvard.toString());
        //function printing college to file
        printToFile(fileName, harvard);
    }

    public static void printToFile(String fileName, College college) throws FileNotFoundException {
        PrintWriter pw = new PrintWriter(new File(fileName));
        pw.println(college.getCollegeName());
        pw.println(college.getNumOfLecturers());
        //write all lecturers to file
        for (int i = 0; i < college.getNumOfLecturers(); i += 1) {
            Lecturer lect = college.getLecturerById(i);
            pw.println(lect.getLect_name());
            pw.println(lect.getFavoriteIceCream());
            pw.println(lect.getNumOfTimesPensFalls());

        }
        pw.close();
    }

    public static College readFromFile(String fileName) throws FileNotFoundException {
        Scanner s = new Scanner(new File(fileName));
        String name, iceCream;
        int penFall;
        //first two lines to declare the college
        College temp = new College(s.nextLine(), s.nextInt());
        //read and add all lectures from file
        while (s.hasNextLine()) {
            name = s.next();
            s.nextLine();
            iceCream = s.next();
            s.nextLine();
            penFall = s.nextInt();
            s.nextLine();
            temp.addLecturer(new Lecturer(name, iceCream, penFall));
        }
        return temp;
    }
    }
}

=====================Lecturer======================================================================================


package College;

public class Lecturer {
    private String lect_name, favoriteIceCream;
    private int numOfTimesPensFalls;
    //Our ids will start form 1000 so we needs private(have no access from outside of class)
    //and ststic counter which starts from 1000
    private static int idStartFrom = 1000;
    private int id;

    public Lecturer(String lect_name, String favoriteIceCream, int numOfTimesPensFalls) {
        this.lect_name = lect_name;
        this.favoriteIceCream = favoriteIceCream;
        //for every new lecturer increment id;
        this.numOfTimesPensFalls = numOfTimesPensFalls;
        this.id = ++idStartFrom;
    }

      public int getNumOfTimesPensFalls() {
        return this.numOfTimesPensFalls;
    }

    public String getLect_name() {
        return lect_name;
    }

    public String getFavoriteIceCream() {
        return favoriteIceCream;
    }

    public int getId() {
        return id;
    }

    @Override
    public String toString() {
        return "Lecturer: " + lect_name +
                "\nId: " + id +
                "\nFavorine ice creame: " + favoriteIceCream +
                "\nNum of times pens falls: " + numOfTimesPensFalls+"\n";
    }
}


===================College=============================================================================


package College;

public class College {
    private String collegeName;
    private int numOfLecturers;
    private Lecturer[] allLecturers;

   public College(String collegeName, int maxNumOfLecturers) {
        this.collegeName = collegeName;
        this.numOfLecturers = 0;
        this.allLecturers = new Lecturer[maxNumOfLecturers];
    }

    //copy constructor
    public College(College other) {
        this.collegeName = other.getCollegeName();
        this.numOfLecturers = other.getNumOfLecturers();
        // for arrays we need to copy all elements and not to bring a link from other's array to constructors one
        this.allLecturers = new Lecturer[other.allLecturers.length];
        //we need to add lecturers from other's array so we do this just for amount of
        //lecturers who exist in other's array
        for (int i = 0; i < other.numOfLecturers; i += 1) {
            this.allLecturers[i] = other.allLecturers[i];
        }
    }

    public String getCollegeName() {
        return collegeName;
    }

    public int getNumOfLecturers() {
        return numOfLecturers;
    }

    public Lecturer getLecturerById(int id){
        return this.allLecturers[id];
    }

    public boolean addLecturer(Lecturer lecturer) {
        //if current amount of lecturers is less than alloved put lecturer to the array,
        // increment current amount of lecturers returns true
        // else return false
        if (this.numOfLecturers <= this.allLecturers.length) {
            this.allLecturers[numOfLecturers] = lecturer;
            this.numOfLecturers += 1;
            return true;
        } else {
            return false;
        }
    }

    //Using buble sort for the array
    public void sortLecturersByLessFall() {
        //array's last element is current number less one
        int ln = this.numOfLecturers;
        Lecturer temp;
        for (int i = 0; i < ln; i += 1) {
            for (int j = 1; j < ln - i; j += 1) {
                //compare by fallen pens
                if (this.allLecturers[j - 1].getNumOfTimesPensFalls() > this.allLecturers[j].getNumOfTimesPensFalls()) {
                    //change lecturer's places
                    temp = this.allLecturers[j - 1];
                    this.allLecturers[j - 1] = this.allLecturers[j];
                    this.allLecturers[j] = temp;
                }
            }
        }
    }

    @Override
    public String toString() {
        String str =  "College: " + collegeName +
                "\nCurrent number of lecturers: " + numOfLecturers+"\n";
        for(int i=0;i<numOfLecturers;i+=1){
            str+=allLecturers[i].toString();
        }
        return str;
    }
}