УП 2.3

3_src_Main.java

public class Main {

    public static void main(String[] args) {
        View view = new View();
    }
}

3_src_Student.java

import java.util.Objects;

public class Student implements Comparable<Student> {
    private int course;
    private int group;
    private String surname;
    private String name;

    public Student(int course, int group, String surname, String name) {
        this.course = course;
        this.group = group;
        this.surname = surname;
        this.name = name;
    }

    public int getCourse() {
        return course;
    }

    public void setCourse(int course) {
        this.course = course;
    }

    public int getGroup() {
        return group;
    }

    public void setGroup(int group) {
        this.group = group;
    }

    public String getSurname() {
        return surname;
    }

    public void setSurname(String surname) {
        this.surname = surname;
    }

    public String getName() {
        return name;
    }

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

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

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Student student = (Student) o;
        return course == student.course &&
                group == student.group &&
                surname.equals(student.surname) &&
                name.equals(student.name);
    }

    @Override
    public int hashCode() {
        return Objects.hash(course, group, surname, name);
    }

    @Override
    public int compareTo(Student o) {
        int diff = surname.compareTo(o.surname);
        if (diff == 0)
            return name.compareTo(o.name);
        return diff;
    }
}

3_src_students.txt

Арташевич|Станислав|1|3

3_src_View.java

import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeNode;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.List;
import java.util.*;

public class View extends JFrame implements ActionListener {
    JButton edit;
    JButton add;
    JButton delete;
    private Map<Integer, Map<Integer, List<Student>>> database;
    private JTree tree;
    private DefaultTreeModel model;

    public View() {
        super("University");
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            database = new HashMap<>(4, 1);
            try (Scanner scanner = new Scanner(new File("src\\students.txt"))) {
                scanner.useDelimiter("[|]|[\r\n]+");
                int course, group;
                String surname, name;
                List<Student> groupList;
                Map<Integer, List<Student>> groupsMap;
                while (scanner.hasNext()) {
                    surname = scanner.next();
                    name = scanner.next();
                    course = scanner.nextInt();
                    group = scanner.nextInt();
                    if (database.containsKey(course)) {
                        if (database.get(course).containsKey(group)) {
                            groupList = database.get(course).get(group);
                            groupList.add(new Student(course, group, surname, name));
                        } else {
                            groupsMap = database.get(course);
                            groupList = new ArrayList<>();
                            groupList.add(new Student(course, group, surname, name));
                            groupsMap.put(group, groupList);
                        }
                    } else {
                        groupsMap = new HashMap<>(12, 1);
                        groupList = new ArrayList<>();
                        groupList.add(new Student(course, group, surname, name));
                        groupsMap.put(group, groupList);
                        database.put(course, groupsMap);
                    }
                }
            }
            DefaultMutableTreeNode root = new DefaultMutableTreeNode("Студенты");
            DefaultMutableTreeNode courseNode, groupNode, studentNode;
            for (int course : database.keySet()) {
                courseNode = new DefaultMutableTreeNode(course + " курс");
                for (int group : database.get(course).keySet()) {
                    groupNode = new DefaultMutableTreeNode(group + " группа");
                    Collections.sort(database.get(course).get(group));
                    for (Student student : database.get(course).get(group)) {
                        studentNode = new DefaultMutableTreeNode(student);
                        groupNode.add(studentNode);
                    }
                    courseNode.add(groupNode);
                }
                root.add(courseNode);
            }
            model = new DefaultTreeModel(root);
            tree = new JTree(model);
            tree.setRowHeight(48);
            tree.setCellRenderer(new CellRenderer());
            setLayout(new BoxLayout(this.getContentPane(), BoxLayout.PAGE_AXIS));
            add(new JScrollPane(tree));
            JPanel panel = new JPanel();
            panel.setLayout(new BoxLayout(panel, BoxLayout.LINE_AXIS));
            add = new JButton();
            add.setIcon(new ImageIcon("src\\add.png"));
            panel.add(Box.createVerticalGlue());
            add.addActionListener(this);
            panel.add(add);
            edit = new JButton();
            edit.setIcon(new ImageIcon("src\\edit.png"));
            panel.add(Box.createVerticalGlue());
            edit.addActionListener(this);
            panel.add(edit);
            delete = new JButton();
            delete.setIcon(new ImageIcon("src\\delete.png"));
            panel.add(Box.createVerticalGlue());
            delete.addActionListener(this);
            panel.add(delete);
            panel.setAlignmentX(Component.LEFT_ALIGNMENT);
            add(Box.createHorizontalGlue());
            add(panel);
            pack();
            setSize(900, 600);
            setLocationRelativeTo(null);
            setVisible(true);
        } catch (FileNotFoundException | ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException e) {
            System.err.println(e.getMessage());
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        int course, group;
        String surname, name;
        JTextField surnameField = new JTextField(15);
        JTextField nameField = new JTextField(15);
        JTextField courseField = new JTextField(1);
        JTextField groupField = new JTextField(2);
        JPanel inputPanel = new JPanel();
        inputPanel.add(new JLabel("Surname"));
        inputPanel.add(surnameField);
        inputPanel.add(Box.createHorizontalStrut(5));
        inputPanel.add(new JLabel("Name"));
        inputPanel.add(nameField);
        inputPanel.add(Box.createHorizontalStrut(5));
        inputPanel.add(new JLabel("Course"));
        inputPanel.add(courseField);
        inputPanel.add(Box.createHorizontalStrut(5));
        inputPanel.add(new JLabel("Group"));
        inputPanel.add(groupField);
        if (e.getSource() == add) {
            surnameField.setText("Иванов");
            nameField.setText("Иван");
            courseField.setText("1");
            groupField.setText("1");
            DefaultMutableTreeNode node = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();
            if (node != null) {
                while (!node.isLeaf())
                    node = node.getFirstLeaf();
                Student student = (Student) node.getUserObject();
                courseField.setText(String.valueOf(student.getCourse()));
                groupField.setText(String.valueOf(student.getGroup()));
            }
            if (JOptionPane.showConfirmDialog(this, inputPanel, "Добавить студента",
                    JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE,
                    new ImageIcon("src\\add.png")) == JOptionPane.OK_OPTION) {
                try {
                    surname = surnameField.getText();
                    name = nameField.getText();
                    course = Integer.parseInt(courseField.getText());
                    group = Integer.parseInt(groupField.getText());
                    if ((group > 12) || (group < 1))
                        throw new NumberFormatException();
                    if ((course > 4) || (course < 1))
                        throw new NumberFormatException();
                    addStudent(course, group, surname, name);
                    tree.updateUI();
                } catch (NumberFormatException ex) {
                    JOptionPane.showMessageDialog(this, "Некорректый ввод", "Добавить студента",
                            JOptionPane.ERROR_MESSAGE, new ImageIcon("src\\add.png"));
                }
            }
        } else if (e.getSource() == edit) {
            DefaultMutableTreeNode node = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();
            if ((node != null) && (node.isLeaf())) {
                Student student = (Student) node.getUserObject();
                courseField.setText(String.valueOf(student.getCourse()));
                groupField.setText(String.valueOf(student.getGroup()));
                surnameField.setText(student.getSurname());
                nameField.setText(student.getName());
                if (JOptionPane.showConfirmDialog(this, inputPanel, "Редактировать студента",
                        JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE,
                        new ImageIcon("src\\edit.png")) == JOptionPane.OK_OPTION) {
                    try {
                        surname = surnameField.getText();
                        name = nameField.getText();
                        course = Integer.parseInt(courseField.getText());
                        if ((course > 4) || (course < 1))
                            throw new NumberFormatException();
                        group = Integer.parseInt(groupField.getText());
                        if ((group > 12) || (group < 1))
                            throw new NumberFormatException();
                        addStudent(course, group, surname, name);
                        deleteStudent(student, node);
                        tree.setSelectionPath(null);
                        tree.updateUI();
                    } catch (NumberFormatException ex) {
                        JOptionPane.showMessageDialog(this, "Некорректый ввод", "Редактировать студента",
                                JOptionPane.ERROR_MESSAGE, new ImageIcon("src\\edit.png"));
                    }
                }

            } else {
                JOptionPane.showMessageDialog(this, "Выберите студента", "Редактировать студента",
                        JOptionPane.INFORMATION_MESSAGE, new ImageIcon("src\\edit.png"));
            }
        } else if (e.getSource() == delete) {
            DefaultMutableTreeNode node = (DefaultMutableTreeNode) tree.getLastSelectedPathComponent();
            if ((node != null) && (node.isLeaf())) {
                Student student = (Student) node.getUserObject();
                surnameField.setText(student.getSurname());
                nameField.setText(student.getName());
                courseField.setText(String.valueOf(student.getCourse()));
                groupField.setText(String.valueOf(student.getGroup()));
                surnameField.setEditable(false);
                nameField.setEditable(false);
                courseField.setEditable(false);
                groupField.setEditable(false);
                if (JOptionPane.showConfirmDialog(this, inputPanel, "Удалить студента",
                        JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE,
                        new ImageIcon("src\\delete.png")) == JOptionPane.OK_OPTION) {
                    deleteStudent(student, node);
                    tree.setSelectionPath(null);
                    tree.updateUI();
                }
            } else {
                JOptionPane.showMessageDialog(this, "Выберите студента", "Удалить студента",
                        JOptionPane.INFORMATION_MESSAGE, new ImageIcon("src\\delete.png"));
            }
        }
    }

    private void insert(DefaultMutableTreeNode parent, DefaultMutableTreeNode child, Iterator<TreeNode> iterator, int s) {
        DefaultMutableTreeNode temp;
        do {
            temp = (DefaultMutableTreeNode) iterator.next();
            if (Integer.parseInt(((String) temp.getUserObject()).replaceAll("\\D+","")) > s)
                break;
        } while (iterator.hasNext());
        if (Integer.parseInt(((String) temp.getUserObject()).replaceAll("\\D+","")) > s) {
            parent.insert(child, parent.getIndex(temp));
        } else {
            parent.add(child);
        }
    }

    private DefaultMutableTreeNode find(DefaultMutableTreeNode root, String s) {
        Iterator<TreeNode> iterator;
        DefaultMutableTreeNode courseNode;
        iterator = root.children().asIterator();
        do {
            courseNode = (DefaultMutableTreeNode) iterator.next();
            if (courseNode.getUserObject().equals(s))
                break;
        } while (iterator.hasNext());
        return courseNode;
    }

    private void addStudent(int course, int group, String surname, String name) {
        List<Student> groupList;
        Map<Integer, List<Student>> groupsMap;
        DefaultMutableTreeNode root = (DefaultMutableTreeNode) model.getRoot();
        DefaultMutableTreeNode courseNode, groupNode, studentNode, temp;
        Student student = new Student(course, group, surname, name);
        Iterator<TreeNode> iterator;
        String sCourse = course + " курс";
        String sGroup = group + " группа";
        if (database.containsKey(course)) {
            if (database.get(course).containsKey(group)) {
                groupList = database.get(course).get(group);
                courseNode = find(root, sCourse);
                groupNode = find(courseNode, sGroup);
                studentNode = new DefaultMutableTreeNode(student);
                iterator = groupNode.children().asIterator();
                do {
                    temp = (DefaultMutableTreeNode) iterator.next();
                    if (((Student) temp.getUserObject()).compareTo(student) > 0)
                        break;
                } while (iterator.hasNext());
                if (((Student) temp.getUserObject()).compareTo(student) > 0) {
                    groupNode.insert(studentNode, groupNode.getIndex(temp));
                    groupList.add(groupNode.getIndex(temp), student);
                } else {
                    groupNode.add(studentNode);
                    groupList.add(student);
                }
            } else {
                groupsMap = database.get(course);
                groupList = new ArrayList<>();
                groupList.add(student);
                groupsMap.put(group, groupList);
                courseNode = find(root, sCourse);
                groupNode = new DefaultMutableTreeNode(sGroup);
                studentNode = new DefaultMutableTreeNode(student);
                groupNode.add(studentNode);
                iterator = courseNode.children().asIterator();
                insert(courseNode, groupNode, iterator, group);
            }
        } else {
            groupsMap = new HashMap<>();
            groupList = new ArrayList<>();
            groupList.add(student);
            groupsMap.put(group, groupList);
            database.put(course, groupsMap);
            courseNode = new DefaultMutableTreeNode(sCourse);
            groupNode = new DefaultMutableTreeNode(sGroup);
            studentNode = new DefaultMutableTreeNode(student);
            groupNode.add(studentNode);
            courseNode.add(groupNode);
            iterator = root.children().asIterator();
            if (iterator.hasNext()) {
                insert(root, courseNode, iterator, course);
            } else {
                root.add(courseNode);
            }
        }
    }

    private void deleteStudent(Student student, DefaultMutableTreeNode studentNode) {
        database.get(student.getCourse()).get(student.getGroup()).remove(student);
        DefaultMutableTreeNode groupNode = (DefaultMutableTreeNode) studentNode.getParent();
        groupNode.remove(studentNode);
        if (groupNode.isLeaf()) {
            database.get(student.getCourse()).remove(student.getGroup());
            DefaultMutableTreeNode courseNode = (DefaultMutableTreeNode) groupNode.getParent();
            courseNode.remove(groupNode);
            if (courseNode.isLeaf()) {
                database.remove(student.getCourse());
                ((DefaultMutableTreeNode) model.getRoot()).remove(courseNode);
            }
        }
    }
}

class CellRenderer extends DefaultTreeCellRenderer {
    private Icon[] icons;
    private JLabel label;

    public CellRenderer() {
        icons = new Icon[]{new ImageIcon("src\\database.png"),
                new ImageIcon("src\\course.png"), new ImageIcon("src\\group.png"),
                new ImageIcon("src\\student.png")};
        super.setFont(new Font("Verdana", Font.PLAIN, 14));
    }

    @Override
    public Component getTreeCellRendererComponent(JTree tree, Object value, boolean sel, boolean expanded, boolean leaf, int row, boolean hasFocus) {
        label = (JLabel) super.getTreeCellRendererComponent(tree, value, sel, expanded,
                leaf, row, hasFocus);
        if (leaf) {
            label.setIcon(icons[3]);
        } else if (value.toString().contains("группа")) {
            label.setIcon(icons[2]);
        } else if (value.toString().contains("курс")) {
            label.setIcon(icons[1]);
        } else {
            label.setIcon(icons[0]);
        }
        return label;
    }
}

icons

https://img.icons8.com/color/48/000000/database.png
https://img.icons8.com/color/48/000000/team-skin-type-7.png
https://img.icons8.com/color/48/000000/add-user-female-skin-type-7.png
https://img.icons8.com/color/48/000000/registration-skin-type-7.png
https://img.icons8.com/color/48/000000/banned-skin-type-7.png
https://img.icons8.com/color/48/000000/user-group-skin-type-7.png
https://img.icons8.com/color/48/000000/person-female-skin-type-7.png