Apartment

import javax.persistence.*;


@Entity
@Table(name = "apartment")
public class Apartment {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id")
    private int id;

    @Column(name ="district", nullable = false)
    private double district;
    @Column(name ="address", nullable = false)
    private String address;
    private double square;
    private int rooms;
    private double price;

    public Apartment(double district, String address, double square, int rooms, double price) {
        this.district = district;
        this.address = address;
        this.square = square;
        this.rooms = rooms;
        this.price = price;
    }

    public Apartment() {
    }

    public int getId() {
        return id;
    }

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

    public double getDistrict() {
        return district;
    }

    public void setDistrict(double district) {
        this.district = district;
    }

    public String getAddress() {
        return address;
    }

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

    public double getSquare() {
        return square;
    }

    public void setSquare(double square) {
        this.square = square;
    }

    public int getRooms() {
        return rooms;
    }

    public void setRooms(int rooms) {
        this.rooms = rooms;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Apartment [" +
                "id=" + id +
                ", district = " + district +
                ", address = '" + address + '\'' +
                ", square = " + square +
                ", rooms = " + rooms +
                ", price = " + price +
                ']';
    }
}

ApartmentDataBaseSetters

import javax.persistence.EntityManager;
import java.util.Scanner;

/* addition to the method changeApartmentParameter in Implementation */

public class ApartmentDataBaseSetters {

    ApartmentDataBaseSetters (){}

    static void setDistrict (Scanner scanner, Apartment a, EntityManager em) {
        System.out.println("Enter new district: ");
        int newDistrict = scanner.nextInt();

        em.getTransaction().begin();
        try {
            a.setDistrict(newDistrict);
            em.getTransaction().commit();
        } catch (Exception e) {
            em.getTransaction().rollback();
        }

    }

    static void setAddress (Scanner scanner, Apartment a, EntityManager em) {
        System.out.println("Enter new address: ");
        String newAddress = scanner.nextLine();
        while (newAddress.isEmpty()) {
            newAddress = scanner.nextLine();
        }

        em.getTransaction().begin();
        try {
            a.setAddress(newAddress);
            em.getTransaction().commit();
        } catch (Exception e) {
            em.getTransaction().rollback();
        }
    }

    static void setSquare (Scanner scanner, Apartment a, EntityManager em) {
        System.out.println("Enter new square: ");
        double newSquare = scanner.nextDouble();

        em.getTransaction().begin();
        try {
            a.setSquare(newSquare);
            em.getTransaction().commit();
        } catch (Exception e) {
            em.getTransaction().rollback();
        }
    }

    static void setRoomsCount (Scanner scanner, Apartment a, EntityManager em) {
        System.out.println("Enter new count of rooms: ");
        int newRooms = scanner.nextInt();

        em.getTransaction().begin();
        try {
            a.setRooms(newRooms);
            em.getTransaction().commit();
        } catch (Exception e) {
            em.getTransaction().rollback();
        }
    }

    static void setPrice (Scanner scanner, Apartment a, EntityManager em) {
        System.out.println("Enter new price: ");
        double newPrice = scanner.nextDouble();

        em.getTransaction().begin();
        try {
            a.setPrice(newPrice);
            em.getTransaction().commit();
        } catch (Exception e) {
            em.getTransaction().rollback();
        }
    }



}

ApartmentSelection

import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import javax.persistence.NonUniqueResultException;
import javax.persistence.Query;

/* addition to the method changeApartmentParameter in Implementation */

public class ApartmentSelection {

    ApartmentSelection(){}

    static Apartment selectApartment(int id, EntityManager em){
        Apartment a = null;

        try {
            Query query = em.createQuery("SELECT a FROM Apartment a WHERE a.id = :id", Apartment.class);
            query.setParameter("id", id);
            a = (Apartment) query.getSingleResult();
        } catch (NoResultException e) {
            System.out.println("Apartment not found");
        } catch (NonUniqueResultException e) {
            System.out.println("Unique result");
        }

        return a;
    }

}

Implementation

import javax.persistence.EntityManager;
import javax.persistence.Query;
import java.util.List;
import java.util.Scanner;

public class Implementation {

    private static EntityManager em;

    Implementation(EntityManager em) {
        Implementation.em = em;
    }

    void addApartment(Scanner scanner) {
        System.out.println("Enter number of district: ");
        int district = scanner.nextInt();

        System.out.println("Enter address: ");
        String address = scanner.nextLine();
        while (address.isEmpty()) {
            address = scanner.nextLine();
        }

        System.out.println("Enter square: ");
        double square = scanner.nextDouble();

        System.out.println("Enter number of rooms: ");
        int rooms = scanner.nextInt();

        System.out.println("Enter price: ");
        double price = scanner.nextDouble();

        em.getTransaction().begin();
        try {
            Apartment apartment = new Apartment(district, address, square, rooms, price);
            em.persist(apartment);
            em.getTransaction().commit();
        } catch (Exception e) {
            em.getTransaction().rollback();
        }
    }

    void deleteApartment(Scanner scanner) {
        System.out.println("Enter client id: ");
        int id = scanner.nextInt();
        System.out.println("Deleted!");

        Apartment apartment = em.find(Apartment.class, id);
        if (apartment == null) {
            System.out.println("Apartment not found");
            return;
        }

        em.getTransaction().begin();
        try {
            em.remove(apartment);
            em.getTransaction().commit();
        } catch (Exception e) {
            em.getTransaction().rollback();
        }
    }

    void showApartments() {
        Query query = em.createQuery("SELECT a FROM Apartment a", Apartment.class);
        List apartments = query.getResultList();

        System.out.println();

        if (apartments.isEmpty()) {
            System.out.println("Empty list. Try to add apartments");
        }

        int count = 1;
        for (Object a : apartments) {
            System.out.println(count + " " + a);
            count++;
        }

    }

    void changeApartmentParameter(Scanner scanner) {
        // For this method two additional classes with static methods are introduced:
        // ApartmentSelection and ApartmentDataBaseSetters

        System.out.println("Enter apartment id: ");
        int id = scanner.nextInt();

        Apartment a = ApartmentSelection.selectApartment(id, em);

        while (true) {
            System.out.println("Enter what you wanna to change: ");
            System.out.println("1. District");
            System.out.println("2. Address");
            System.out.println("3. Square");
            System.out.println("4. Rooms");
            System.out.println("5. Price");
            System.out.println();
            System.out.println("Choose number of operation: ");

            int number = scanner.nextInt();

            switch (number) {
                case 1:
                    ApartmentDataBaseSetters.setDistrict(scanner, a, em);
                    return;

                case 2:
                    ApartmentDataBaseSetters.setAddress(scanner, a, em);
                    return;

                case 3:
                    ApartmentDataBaseSetters.setSquare(scanner, a, em);
                    return;

                case 4:
                    ApartmentDataBaseSetters.setRoomsCount(scanner, a, em);
                    return;

                case 5:
                    ApartmentDataBaseSetters.setPrice(scanner, a, em);
                    return;

                default:
                    System.out.println("There is no parameter like that");
                    System.out.println("Try again");
                    System.out.println();
                    break;

            }
        }
    }
}

Main

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import java.util.Scanner;

public class Main {

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

        EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPA");
        EntityManager em = emf.createEntityManager();

        Implementation impl = new Implementation(em);

        try {


            try {

                while (true) {
                    System.out.println();
                    System.out.println("1. Add Apartment: ");
                    System.out.println("2. Delete Apartment: ");
                    System.out.println("3. Change apartment characteristic");
                    System.out.println("4. Show Apartments: ");
                    System.out.println("5. Exit");
                    System.out.println();
                    System.out.println("Choose number of operation: ");

                    int choose = scanner.nextInt();

                    switch (choose) {

                        case 1:
                            impl.addApartment(scanner);
                            break;

                        case 2:
                            impl.deleteApartment(scanner);
                            break;

                        case 3:
                            impl.changeApartmentParameter(scanner);
                            break;

                        case 4:
                            impl.showApartments();
                            break;

                        case 5:
                            return;

                        default:
                            System.out.println("There is no operation like that");
                            System.out.println("Try again");
                            System.out.println();
                            break;


                    }

                }

            } finally {
                scanner.close();
                em.close();
                emf.close();
            }
        } catch (Exception e) {
            e.printStackTrace();

        }

    }

}

persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">
    <persistence-unit name="JPA">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

        <properties>
            <property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver" />
            <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/hhw"/>
            <property name="javax.persistence.jdbc.user" value="root" />
            <property name="javax.persistence.jdbc.password" value="12345" />
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
            <property name="hibernate.hbm2ddl.auto" value="create"/>
        </properties>
    </persistence-unit>
</persistence>