Интерфейс AbstractController:
package DAO;

import java.sql.Connection;
import java.sql.SQLException;

public interface AbstractController<E> {
    E add(Connection connection,E e) throws SQLException;
    boolean update(Connection connection,E e) throws SQLException;
}

Класс DepartmentDAO:
package DAO;

import Enity.Department;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class DepartmentDAO implements AbstractController<Department> {

    @Override
    public Department add(Connection connection, Department department) throws SQLException {
        String sql = "insert into department (id_university,id_faculty,name) values (?,?,?)";
        try (PreparedStatement statement = connection.prepareStatement(sql)) {
            statement.setInt(1,department.getId_university());
            statement.setInt(2,department.getId_faculty());
            statement.setString(3,department.getName());
            statement.execute();
        } catch (SQLException e) {
            e.getMessage();
        }
        return department;
    }

    @Override
    public boolean update(Connection connection, Department department) throws SQLException {
        try(PreparedStatement statement = connection.prepareStatement("update department set name = '" +
                department.getName() +"' where id = " + department.getId() + ";")) {
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }
}

Класс FacultyDAO:
package DAO;

import Enity.Faculty;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;

public class FacultyDAO implements AbstractController<Faculty> {

    @Override
    public Faculty add(Connection connection, Faculty faculty) throws SQLException {
        String sql = "insert into faculty (id_university,name) values (?,?)";
        try (PreparedStatement statement = connection.prepareStatement(sql)) {
            statement.setInt(1,faculty.getId_university());
            statement.setString(2,faculty.getName());
            statement.execute();
        } catch (SQLException e) {
            e.getMessage();
        }
        return faculty;
    }

    @Override
    public boolean update(Connection connection, Faculty faculty) throws SQLException {
        try(PreparedStatement statement = connection.prepareStatement("update faculty set name = '" +
                faculty.getName() +"' where id = " + faculty.getId() + ";")) {
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }
}

Класс UniversityDAO:
package DAO;

import Enity.University;

import java.sql.*;

public class UniversityDAO implements AbstractController<University> {

    @Override
    public University add(Connection connection, University university) throws SQLException {
        String sql = "insert into university (name,address) values (?,?)";

        try (PreparedStatement statement = connection.prepareStatement(sql)) {
            statement.setString(1,university.getName());
            statement.setString(2,university.getAddress());
            statement.execute();
        } catch (SQLException e) {
            e.getMessage();
        }
        return university;
    }

    @Override
    public boolean update(Connection connection, University university) throws SQLException {
        try(PreparedStatement statement = connection.prepareStatement("update university set name = '" +
                university.getName() +"',address='"+university.getAddress()+"' where id = " + university.getId() + ";")) {
            statement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
            return false;
        }
        return true;
    }
}

Класс Department:
package Enity;

public class Department {
    private int id;
    private int id_university;
    private int id_faculty;
    private String name;

    public Department(){
    }

    public Department(int id){
        this.id=id;
    }

    public Department(int id,int id_university,int id_faculty ,String name){
        this.id=id;
        this.id_university=id_university;
        this.id_faculty=id_faculty;
        this.name=name;
    }

    public Department(int id_university,int id_faculty,String name)
    {
        this.id_university=id_university;
        this.id_faculty=id_faculty;
        this.name=name;
    }

    public Department(String name){
        this.name=name;
    }

    public int getId(){return id;}

    public int getId_university(){return id_university;}

    public int getId_faculty(){return id_faculty;}

    public String getName(){return name;}

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

    public void setId_university(int id_university){this.id_university=id_university;}

    public void setId_faculty(int id_faculty){this.id_faculty=id_faculty;}

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

    @Override
    public String toString(){return name;}
}

Класс Faculty:
package Enity;

    public class Faculty {
    private int id;
    private int id_university;
    private String name;

    public Faculty(){
    }

    public Faculty(int id,int id_university, String name){
        this.id=id;
        this.id_university=id_university;
        this.name=name;
    }

    public Faculty(int id_university,String name){
        this.id_university=id_university;
        this.name=name;
    }


    public Faculty(String name){
        this.name=name;
    }

    public int getId(){return id;}

    public int getId_university(){return id_university;}

    public String getName(){return name;}

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

    public void setId_university(int id_university){this.id_university=id_university;}

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

    @Override
    public String toString(){return name;}
}

Класс University:
package Enity;

public class University {
    private int id;
    private String name;
    private String address;

    public University(){
    }

    public University(int id,String name, String address){
        this.id=id;
        this.name=name;
        this.address=address;
    }

    public University(String name, String address){
        this.name=name;
        this.address=address;
    }

    public int getId(){return id;}

    public String getName(){
        return name;
    }

    public String getAddress(){
        return address;
    }

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

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

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

    @Override
    public String toString(){
        return name;
    }
}

Класс ConnectDataBase:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public final class ConnectDataBase {

    public static Connection connDataBase() {
        final String URL = "jdbc:postgresql://127.0.0.1:5432/course";
        final String USERNAME = "postgres";
        final String PASSWORD = "S123456s";

        Connection connection = null;
        try {
            Class.forName("org.postgresql.Driver");
            connection = DriverManager.getConnection(URL, USERNAME, PASSWORD);
            System.out.println("Соединение с БД установленно!");
        } catch (ClassNotFoundException | SQLException ex) {
            System.err.println("Нет коннекта к базе: " + ex);
        }
        return connection;
    }
}

Класс GUI:
import DAO.DepartmentDAO;
import DAO.FacultyDAO;
import DAO.UniversityDAO;
import Enity.Department;
import Enity.Faculty;
import Enity.University;

import javax.swing.*;
import java.awt.event.*;
import java.sql.*;

public class GUI extends JDialog {
    Connection connection =ConnectDataBase.connDataBase();
    private DefaultListModel dlmUniversity = new DefaultListModel<>();
    private DefaultListModel dlmFaculty = new DefaultListModel<>();
    private DefaultListModel dlmDepartment = new DefaultListModel<>();
    UniversityDAO universityDAO = new UniversityDAO();
    FacultyDAO facultyDAO = new FacultyDAO();
    DepartmentDAO departmentDAO = new DepartmentDAO();
    String getNameUni;
    String getNameFacu;
    String getNameDepa;
    int getId_uni;
    int getId_facu;
    int getId_depa;
    private JPanel contentPane;
    private JButton addUniversity;
    private JButton updateUniversity;
    private JList listUniversity;
    private JList listFaculty;
    private JList listDepartment;
    private JButton addFaculty;
    private JButton updateFaculty;
    private JButton addDepartment;
    private JButton updateDepartment;
    private JButton selectUni;
    private JButton selectFaculty;
    private JButton selectDepartment;

    public GUI() throws SQLException {

        addUniversity.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                University university = new University(JOptionPane.showInputDialog(contentPane,"Введите название вуза"),JOptionPane.showInputDialog(contentPane,"Введите адрес вуза"));
                try {
                    dlmUniversity.add(dlmUniversity.getSize(),universityDAO.add(connection,university) );
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
                validate();
            }
        });

        addFaculty.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                Faculty faculty = new Faculty(getId_uni,JOptionPane.showInputDialog(contentPane,"Введите название факультета"));
                try {
                    dlmFaculty.add(dlmFaculty.getSize(),facultyDAO.add(connection,faculty) );
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
                validate();
            }
        });

        addDepartment.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                Department department = new Department(getId_uni,getId_facu,JOptionPane.showInputDialog(contentPane,"Введите название кафедры"));
                try {
                    dlmDepartment.add(dlmDepartment.getSize(),departmentDAO.add(connection,department) );
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
                validate();
            }
        });

        updateUniversity.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                University university = new University(getId_uni,JOptionPane.showInputDialog(contentPane,"Введите новое название ВУЗа"),JOptionPane.showInputDialog(contentPane,"Введите новый адрес вуза"));
                try {
                    //University university = new University(getId_uni,JOptionPane.showInputDialog(contents,"Введите новое название ВУЗа"),JOptionPane.showInputDialog(contents,"Введите новый адрес вуза"));
                    universityDAO.update(connection,university);
                    dlmUniversity.removeAllElements();
                    Statement statement = connection.createStatement();
                    ResultSet resultSet = statement.executeQuery("select name,address from university");
                    while (resultSet.next()) {
                        String name = resultSet.getString("name");
                        String address = resultSet.getString("address");
                        University university1 = new University(name,address);
                        dlmUniversity.addElement(university1);
                    }
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }
        });

        updateFaculty.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                Faculty faculty = new Faculty(getId_facu,getId_uni,JOptionPane.showInputDialog(contentPane,"Введите новое название Факультета"));
                try {
                    facultyDAO.update(connection,faculty);
                    dlmFaculty.removeAllElements();
                    try {
                        Statement statement = connection.createStatement();
                        ResultSet resultSet = statement.executeQuery("select name from faculty where id_university="+getId_uni);
                        while (resultSet.next()) {
                            String name = resultSet.getString("name");
                            Faculty faculty1 = new Faculty(name);
                            dlmFaculty.addElement(faculty1);
                        }}
                    catch (SQLException ex){
                        ex.printStackTrace();
                    }
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }
        });

        updateDepartment.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                Department department = new Department(getId_depa,getId_uni,getId_facu,JOptionPane.showInputDialog(contentPane,"Введите новое название Кафедры"));
                try {
                    departmentDAO.update(connection,department);
                    dlmDepartment.removeAllElements();
                    try {
                        Statement statement = connection.createStatement();
                        ResultSet resultSet = statement.executeQuery("select name from department where id_university="+getId_uni+"and id_faculty="+getId_facu);
                        while (resultSet.next()) {
                            String name = resultSet.getString("name");
                            Department department1 = new Department(name);
                            dlmDepartment.addElement(department1);
                        }}
                    catch (SQLException ex){
                        ex.printStackTrace();
                    }
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }
        });

        selectUni.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    Statement statement = connection.createStatement();
                    ResultSet resultSet = statement.executeQuery("select address from university where id="+getId_uni);
                    while (resultSet.next()) {
                        JOptionPane.showMessageDialog(contentPane,"Адрес: "+resultSet.getString("address"));
                    }
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }

            }
        });

        Statement statement = connection.createStatement();
        ResultSet resultSet = statement.executeQuery("select name,address from university");
        while (resultSet.next()) {
            String name = resultSet.getString("name");
            String address = resultSet.getString("address");
            University university = new University(name,address);
            dlmUniversity.addElement(university);
        }
        listUniversity.setModel(dlmUniversity);

        listUniversity.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                if ( e.getClickCount() == 2 ){
                    dlmFaculty.removeAllElements();
                    dlmDepartment.removeAllElements();
                    getNameUni=listUniversity.getSelectedValue().toString();
                    try{
                        PreparedStatement preparedStatement = connection.prepareStatement("select id from university where name=?");
                        preparedStatement.setString(1, getNameUni);
                        ResultSet resultSet = preparedStatement.executeQuery();
                        while (resultSet.next()) {
                            getId_uni = resultSet.getInt(1);
                        }
                    } catch (SQLException ex) {
                        ex.printStackTrace();
                    }
                    try {
                        ResultSet resultSet = statement.executeQuery("select name from faculty where id_university="+getId_uni);
                        while (resultSet.next()) {
                            String name = resultSet.getString("name");
                            Faculty faculty = new Faculty(name);
                            dlmFaculty.addElement(faculty);
                        }}
                    catch (SQLException ex){
                        ex.printStackTrace();
                    }
                }
            }
        });

        listFaculty.setModel(dlmFaculty);

        listFaculty.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                if ( e.getClickCount() == 2 ){
                    dlmDepartment.removeAllElements();
                    getNameFacu = listFaculty.getSelectedValue().toString();
                    try{
                        PreparedStatement preparedStatement = connection.prepareStatement("select id from faculty where name=?");
                        preparedStatement.setString(1, getNameFacu);
                        ResultSet resultSet = preparedStatement.executeQuery();
                        while (resultSet.next()) {
                            getId_facu = resultSet.getInt(1);
                        }
                    } catch (SQLException ex) {
                        ex.printStackTrace();
                    }
                    try {
                        ResultSet resultSet = statement.executeQuery("select name from department where id_university="+getId_uni+"and id_faculty="+getId_facu);
                        while (resultSet.next()) {
                            String name = resultSet.getString("name");
                            Department department = new Department(name);
                            dlmDepartment.addElement(department);
                        }}
                    catch (SQLException ex){
                        ex.printStackTrace();
                    }
                }
            }
        });

        listDepartment.setModel(dlmDepartment);

        listDepartment.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                getNameDepa = listDepartment.getSelectedValue().toString();
                try{
                    PreparedStatement preparedStatement = connection.prepareStatement("select id from department where name=?");
                    preparedStatement.setString(1, getNameDepa);
                    ResultSet resultSet = preparedStatement.executeQuery();
                    while (resultSet.next()) {
                        getId_depa = resultSet.getInt(1);
                    }
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }
        });

        setContentPane(contentPane);
        setModal(true);

        setDefaultCloseOperation(DO_NOTHING_ON_CLOSE);
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                onCancel();
            }
        });

        contentPane.registerKeyboardAction(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                onCancel();
            }
        }, KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0), JComponent.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
    }

    private void onOK() {
        dispose();
    }

    private void onCancel() {
        dispose();
    }

    public static void main(String[] args) throws SQLException, ClassNotFoundException, UnsupportedLookAndFeelException, InstantiationException, IllegalAccessException {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        GUI dialog = new GUI();
        dialog.pack();
        dialog.setVisible(true);
        System.exit(0);
    }
}