// Hoffentlich nur das unnötigste herrausgestrichen


Verwaltung

public class NachhilfeVerwaltung {
    private BinarySearchTree<Subject> management;
    private BinarySearchTree<Student> studentmanager;

    public NachhilfeVerwaltung() {
        studentmanager = new BinarySearchTree<Student>();
        management = new BinarySearchTree<Subject>();
        addSubject(new Subject("Mathe"));
        addSubject(new Subject("Informatik"));
        addSubject(new Subject("Deutsch"));
        addSubject(new Subject("Englisch"));
        addSubject(new Subject("Religion"));
        addSubject(new Subject("Sport"));
    }

    public void addSubject(Subject pSubject) {
        if(pSubject != null && management.search(pSubject) == null) {
            management.insert(pSubject);
            System.out.println("Subject: " + pSubject.getName() + " has been added");
        }
    }

    public Subject searchSubject(Subject pSubject) {
        if(pSubject != null) {
            return management.search(pSubject);
        } else {
            return null;
        }
    }

    public void removeSubject(Subject pSubject) {
        management.remove(pSubject);
        System.out.println("Subject: " + pSubject.getName() + " has been removed!");
    }

    public List<Subject> getAllSubjects() {
        if(!management.isEmpty()) {
            List<Subject> tmp = new List<Subject>();
            tmp = inOrderSubject(management,tmp);

            tmp.toFirst();
            while(tmp.hasAccess()) {
                System.out.println("Subject: " + tmp.getContent().getName());
                tmp.next();
            }

            return tmp;
        } else {
            System.out.println("ALARM");
            return null;
        }
    }

    public int numberOfSubjects() {
        List<Subject> tmp = new List<Subject>();
        tmp = inOrderSubject(management,tmp);
        tmp.toFirst();
        int i = 0;
        while(tmp.hasAccess()) {
            i++;
            tmp.next();
        }
        return i;
    }

    public int numberOfStudents() {
        List<Student> tmp = new List<Student>();
        tmp = inOrderStudent(studentmanager,tmp);
        tmp.toFirst();
        int i = 0;
        while(tmp.hasAccess()) {
            i++;
            tmp.next();
        }
        return i;
    }

    public int numberOfTutor() {
        List<Subject> tmp = new List<Subject>();
        tmp = getAllSubjects();
        tmp.toFirst();
        int i = 0;
        while(tmp.hasAccess()) {
            i = i + tmp.getContent().numberOfTutor();
            tmp.next();
        }
        return i;
    }


    public void addStudent(Student pStudent) {
        if(pStudent != null && studentmanager.search(pStudent) == null) {
            studentmanager.insert(pStudent);
            System.out.println("Student: " + pStudent.getSurname() + " " + pStudent.getForename() + " has been added");
        }
    }

    public Student searchStudent(Student pStudent) {
        if(pStudent != null) {
            return studentmanager.search(pStudent);
        } else {
            return null;
        }
    }

    public void removeStudent(Student pStudent) {
        studentmanager.remove(pStudent);
        System.out.println("Subject: " + pStudent.getSurname() + " " + pStudent.getForename() + " has been removed!");
    }


    public List<Student> getAllStudents() {
        if(!studentmanager.isEmpty()) {
            List<Student> tmp = new List<Student>();
            tmp = inOrderStudent(studentmanager,tmp);

            tmp.toFirst();
            while(tmp.hasAccess()) {
                System.out.println("Student: " + tmp.getContent().getSurname() + " " + tmp.getContent().getForename()
                        +  " "); //+ tmp.getContent().getNumberOfSubjects()[].getName());
                tmp.next();
            }

            return tmp;
        } else {
            System.out.println("ALARM");
            return null;
        }
    }

    private List<Student> inOrderStudent(BinarySearchTree<Student> pCurrentTree, List<Student> pList) {
        List<Student> sorted = pList;
        if(!pCurrentTree.isEmpty()) {
            if(!pCurrentTree.getLeftTree().isEmpty()) {
            inOrderStudent(pCurrentTree.getLeftTree(), sorted);
            }
            sorted.append(pCurrentTree.getContent());
            if(!pCurrentTree.getRightTree().isEmpty()) {
            inOrderStudent(pCurrentTree.getRightTree(), sorted);
            }
        }
        return sorted;
    }

    private List<Subject> inOrderSubject(BinarySearchTree<Subject> pCurrentTree, List<Subject> pList) {
        List<Subject> sorted = pList;
        if(!pCurrentTree.isEmpty()) {
            if(!pCurrentTree.getLeftTree().isEmpty()) {
            inOrderSubject(pCurrentTree.getLeftTree(), sorted);
            }
            sorted.append(pCurrentTree.getContent());
            if(!pCurrentTree.getRightTree().isEmpty()) {
            inOrderSubject(pCurrentTree.getRightTree(), sorted);
            }
        }
        return sorted;
    }

}

Tutor

public class Tutor {

    private String surname;
    private String forename;

    private List<Student> students;

    private boolean ausgebucht;
    private int maxAvailablePositions;
    private int occupiedPositions;

    public Tutor(String pSurname, String pForename, int pMaxAvailablePositions) {
        surname = pSurname;
        forename = pForename;
        maxAvailablePositions = pMaxAvailablePositions;
        students = new List<Student>();
        ausgebucht = false;

    }

    public void erhoeheBuchung(Student pStudent) {
        students.insert(pStudent);
        if(occupiedPositions < maxAvailablePositions) {
            occupiedPositions++;
        } else {
            ausgebucht = true;
            System.out.println("Der Lehrer hat keine Stellen frei");
        }
    }

    public void loescheBuchung(Student pStudent) {
        students.toFirst();
        while(students.hasAccess() && !students.getContent().getForename().equals(pStudent.getForename()) &&
                !students.getContent().getSurname().equals(pStudent.getSurname())) {
            if(students.getContent().getForename().equals(pStudent.getForename()) && students.getContent().getSurname().equals(pStudent.getSurname())) {
                students.remove();
            } else {
                students.next();
            }
        }
        occupiedPositions--;
        ausgebucht = false;
    }

    public String getSurname() {
        return surname;
    }

    public void setSurname(String pSurname) {
        surname = pSurname;
    }

    public String getForename() {
        return forename;
    }

    public void setForename(String forename) {
        this.forename = forename;
    }

    public boolean getAusgebucht() {
        return ausgebucht;
    }

    public void setAusgebucht(boolean ausgebucht) {
        this.ausgebucht = ausgebucht;
    }

    public int getmaxAvailablePositions() {
        return maxAvailablePositions;
    }


    public int getOccupiedPositions() {
        return occupiedPositions;
    }


}

Student


public class Student implements ComparableContent<Student> {
    private String forename;
    private String surname;
    private Subject[] numberOfSubjects;

    public Student(String pForename, String pSurname) {
        forename = pForename;
        surname = pSurname;
        numberOfSubjects = null;
    }

    public Student(String pForename, String pSurname, Subject[] pNumberOfSubjects) {
        forename = pForename;
        surname = pSurname;
        numberOfSubjects = pNumberOfSubjects;
    }


    public String getForename() {
        return forename;
    }

    public void setForename(String forename) {
        this.forename = forename;
    }

    public String getSurname() {
        return surname;
    }

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


    public Subject[] getNumberOfSubjects() {
        return numberOfSubjects;
    }


    public void setNumberOfSubjects(Subject[] numberOfSubjects) {
        this.numberOfSubjects = numberOfSubjects;
    }


    @Override
    public boolean isGreater(Student pContent) {
        if(surname.compareToIgnoreCase(pContent.getSurname()) > 0) {
            return true;
        }
        return false;
    }

    @Override
    public boolean isEqual(Student pContent) {
        if(surname.equalsIgnoreCase(pContent.getSurname())) {
            return true;
        }
        return false;
    }

    @Override
    public boolean isLess(Student pContent) {
        if(surname.compareToIgnoreCase(pContent.getSurname()) < 0) {
            return true;
        }
        return false;
    }
}

Subjects


public class Subject implements ComparableContent<Subject>{

    private String name;
    private List<Tutor> tutor;

    public Subject(String pName) {
        name = pName;
        tutor = new List<Tutor>();
    }

    public Tutor searchTutor(String pForename, String pSurname) {
        tutor.toFirst();
        while(tutor.hasAccess() && !tutor.getContent().getForename().equalsIgnoreCase(pForename) &&
                !tutor.getContent().getSurname().equalsIgnoreCase(pSurname)) {
            tutor.next();
        }
        return tutor.getContent();
    }

    public String getName() {
        return name;
    }

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

    public List<Tutor> getAllTeacher() {
        if(tutor.isEmpty()) {
            System.out.println("Keine Lehrer vorhanden");
            return null;
        }
        return tutor;
    }

    public int numberOfTutor() {
        int number = 0;
        tutor.toFirst();
        while(tutor.hasAccess()) {
            number++;
            tutor.next();
        }
        return number;
    }

    public int numberOfFreeSpace() {
        int number = 0;
        tutor.toFirst();
        while(tutor.hasAccess()) {
            if(!tutor.getContent().getAusgebucht()) {
                number++;
            }
            tutor.next();
        }
        return number;
    }

    private void sortList() {
        int numberOfTutors = 0;
        tutor.toFirst();
        while(tutor.hasAccess()) {
            numberOfTutors++;
            tutor.next();
        }
        Tutor[] savedTutors = new Tutor[numberOfTutors];
        tutor.toFirst();
        for (int i = 0; i < numberOfTutors; i++) {
            savedTutors[i] = tutor.getContent();
            tutor.remove();
            tutor.next();
        }

        //BubbleSort
        boolean getauscht;
        do {
            getauscht = false;
            for(int index = 1; index < savedTutors.length; index++) {
                if(savedTutors[index - 1].getSurname().compareToIgnoreCase(savedTutors[index].getSurname()) > 0) {
                    Tutor tmp = savedTutors[index - 1];
                    savedTutors[index - 1] = savedTutors[index];
                    savedTutors[index] = tmp;
                    getauscht = true;
                }
            }
        } while(getauscht);
        // Zurück
        for (int i = 0; i < savedTutors.length; i++) {
            tutor.append(savedTutors[i]);
        }

    }

    public void addTeacher(Tutor pTutor) {
        tutor.append(pTutor);
        sortList();
    }

    public void removeTeacher(Tutor pTutor) {
        if(tutor.isEmpty()) {
            System.out.println("Liste ist leer");
        } else {
            tutor.toFirst();
            while(tutor.hasAccess() && !tutor.getContent().getSurname().equals(pTutor.getSurname()) &&
                    !tutor.getContent().getForename().equals(pTutor.getForename())) {
                tutor.next();
            }
            tutor.remove();
        }
    }

    @Override
    public boolean isGreater(Subject pContent) {
        if(name.compareToIgnoreCase(pContent.getName()) > 0) {
            return true;
        }
        return false;
    }

    @Override
    public boolean isEqual(Subject pContent) {
        if(name.equalsIgnoreCase(pContent.getName())) {
            return true;
        }
        return false;
    }

    @Override
    public boolean isLess(Subject pContent) {
        if(name.compareToIgnoreCase(pContent.getName()) < 0) {
            return true;
        }
        return false;
    }

}

GUINachhilfe

public class GUINachhilfe extends JFrame {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    GUINachhilfe frame = new GUINachhilfe();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public GUINachhilfe() {
        nv = new NachhilfeVerwaltung();

        pZ = new PanelZusammenfassung(nv);
        pS = new PanelSubject(nv);
        pZu = new PanelZuweisung(nv);
        pV = new PanelVerwaltung(nv);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 790, 465);
        contentPane = new JPanel();
        contentPane.setBackground(new Color(47, 79, 79));
        contentPane.setForeground(new Color(255, 255, 255));
        contentPane.setBorder(new LineBorder(new Color(0, 0, 255), 2));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        allPanels = new JPanel();
        allPanels.setBackground(new Color(0, 128, 128));
        allPanels.setBounds(0, 0, 204, 418);
        contentPane.add(allPanels);
        allPanels.setLayout(null);

        panelZusammenfassung = new JPanel();
        panelZusammenfassung.setBackground(new Color(0, 139, 139));
        panelZusammenfassung.addMouseListener(new PanelMouseButtonAdapter(panelZusammenfassung){
            @Override
            public void mousePressed(MouseEvent e) {
                activatePanel(pZ);
            }
        });
        panelZusammenfassung.setBounds(0, 140, 204, 40);
        allPanels.add(panelZusammenfassung);
        panelZusammenfassung.setLayout(null);


        panelSubjects = new JPanel();
        panelSubjects.addMouseListener(new PanelMouseButtonAdapter(panelSubjects) {
            @Override
            public void mousePressed(MouseEvent e) {
                activatePanel(pS);
            }
        });
        panelSubjects.setBackground(new Color(0, 139, 139));
        panelSubjects.setBounds(0, 180, 204, 40);
        allPanels.add(panelSubjects);
        panelSubjects.setLayout(null);


        panelZuweisen = new JPanel();
        panelZuweisen.setBackground(new Color(0, 139, 139));
        panelZuweisen.addMouseListener(new PanelMouseButtonAdapter(panelZuweisen) {
            @Override
            public void mousePressed(MouseEvent e) {
                activatePanel(pZu);
            }
        });

        panelZuweisen.setBounds(0, 220, 204, 40);
        allPanels.add(panelZuweisen);
        panelZuweisen.setLayout(null);


        panelVerwaltung = new JPanel();
        panelVerwaltung.setBackground(new Color(0, 139, 139));
        panelVerwaltung.addMouseListener(new PanelMouseButtonAdapter(panelVerwaltung) {
            @Override
            public void mousePressed(MouseEvent e) {
                activatePanel(pV);
            }
        });
        panelVerwaltung.setBounds(0, 260, 204, 40);
        allPanels.add(panelVerwaltung);
        panelVerwaltung.setLayout(null);


        panelContent = new JPanel();
        panelContent.setBackground(new Color(47, 79, 79));
        panelContent.setBounds(207, 0, 565, 418);

        panelContent.add(pS);
        panelContent.add(pV);
        panelContent.add(pZu);
        panelContent.add(pZ);


        contentPane.add(panelContent);
        panelContent.setLayout(null);
    }

    public void activatePanel(JPanel selectedPanel) {
        pS.setVisible(false);
        pZ.setVisible(false);
        pZu.setVisible(false);
        pV.setVisible(false);
        if(selectedPanel.equals(pZ)) {
            pZ.updateLabel(String.valueOf(nv.numberOfStudents()), String.valueOf(nv.numberOfSubjects()),
                    String.valueOf(nv.numberOfTutor()));
        }
        selectedPanel.setVisible(true);

    }

    private class PanelMouseButtonAdapter extends MouseAdapter {
        JPanel panel;
        public PanelMouseButtonAdapter(JPanel panel) {
            this.panel = panel;
        }

        @Override
        public void mouseEntered(MouseEvent e) {
            panel.setBackground(new Color(112,128,144));
        }

        @Override
        public void mouseExited(MouseEvent e) {
            panel.setBackground(new Color(0,139,139));
        }

        @Override
        public void mousePressed(MouseEvent e) {
            panel.setBackground(new Color(60,179,113));
        }

        @Override
        public void mouseReleased(MouseEvent e) {
            panel.setBackground(new Color(112,128,144));
        }
    }
}


GUINewStudent

public class GUINewStudent extends JFrame {


    private NachhilfeVerwaltung nv;

    public GUINewStudent(NachhilfeVerwaltung pNv) {
        nv = pNv;

        if(nv.numberOfSubjects() != 0) {
        String[] subjects = new String[nv.numberOfSubjects()];
        List<Subject> tmp = nv.getAllSubjects();
        tmp.toFirst();
        for(int i = 0; i < subjects.length; i++) {
            subjects[i] = tmp.getContent().getName();
            tmp.next();
        }

        list = new JList<String>(subjects);

        list.setLayoutOrientation(JList.HORIZONTAL_WRAP);
        list.setVisibleRowCount(3);
        list.setFont(new Font("Arial", Font.PLAIN, 20));
        list.setBounds(12, 247, 408, 164);
        contentPane.add(list);
        }
        btnNewButton = new JButton("Erstellen");
        btnNewButton.setFont(new Font("Arial", Font.PLAIN, 20));
        btnNewButton.setBounds(146, 422, 154, 25);
        btnNewButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                int[] test = list.getSelectedIndices();
                Subject[] test1 = new Subject[test.length];
                for (int i = 0; i < test.length; i++) {
                    test1[i] = new Subject(list.getModel().getElementAt(i));
                }
                nv.addStudent(new Student(textName.getText(),textVorname.getText(), test1));
                nv.getAllStudents();
                dispose();
            }
        });
        contentPane.add(btnNewButton);
    }


}


GUINewTutor

public class GUINewTutor extends JFrame {

    private NachhilfeVerwaltung nv;

    public GUINewTutor(NachhilfeVerwaltung pNv) {
        nv = pNv;

        btnNewButton = new JButton("Erstellen");
        btnNewButton.setFont(new Font("Arial", Font.PLAIN, 20));
        btnNewButton.setBounds(146, 422, 154, 25);
        btnNewButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                int[] auswahl = list.getSelectedIndices();
                Subject[] subjects = new Subject[auswahl.length];
                for (int i = 0; i < auswahl.length; i++) {
                    subjects[i] = new Subject(list.getModel().getElementAt(i));
                }
                for(Subject s : subjects) {
                    nv.searchSubject(s).addTeacher(new Tutor(textName.getText(),textVorname.getText(), auswahl.length));
                }
                dispose();
            }
        });
        contentPane.add(btnNewButton);

        if(nv.numberOfSubjects() != 0) {
            String[] subjects = new String[nv.numberOfSubjects()];
            List<Subject> tmp = nv.getAllSubjects();
            tmp.toFirst();
            for(int i = 0; i < subjects.length; i++) {
                subjects[i] = tmp.getContent().getName();
                tmp.next();
            }
            list = new JList<String>(subjects);

            list.setLayoutOrientation(JList.HORIZONTAL_WRAP);
            list.setVisibleRowCount(3);
            list.setFont(new Font("Arial", Font.PLAIN, 20));
            list.setBounds(12, 275, 408, 145);
            contentPane.add(list);
            }
    }
}

PanelZusammenfassung

public class PanelZusammenfassung extends JPanel {

    private NachhilfeVerwaltung nv;


    public PanelZusammenfassung(NachhilfeVerwaltung pNv) {
        nv = pNv;
        setBackground(new Color(47, 79, 79));
        setBounds(0,0,564,418);
        setLayout(null);


        setVisible(false);
    }
    public void updateLabel(String pSchueler, String pFach, String pLehrer) {
        labelAnzahlStudents.setText(pSchueler);
        labelAnzahlSubjects.setText(pFach);
        labelAnzahlTutor.setText(pLehrer);
    }
}


PanelSubject

public class PanelSubject extends JPanel {
    private JTextField txtFachname;
    private JTextArea textArea;

    private NachhilfeVerwaltung nv;

    public PanelSubject(NachhilfeVerwaltung pNv) {
        nv = pNv;


        JButton buttonSuche = new JButton("Suche");
        buttonSuche.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                buttonSuche_ActionPerformed(e);

            }

        });
        setVisible(false);
    }

    protected void buttonSuche_ActionPerformed(ActionEvent e) {
        textArea.setText("Anzahl Lehrer: " + nv.searchSubject(new Subject(txtFachname.getText())).numberOfTutor() + "\n" +
                        "Freie Stellen: " + nv.searchSubject(new Subject(txtFachname.getText())).numberOfFreeSpace());
    }
}


PanelZuweisung


public class PanelZuweisung extends JPanel {
    private JList<String> list;
    private DefaultListModel<String> model;

    private NachhilfeVerwaltung nv;

    public PanelZuweisung(NachhilfeVerwaltung pNv) {
        nv = pNv;

        buttonSuche = new JButton("Suche");
        buttonSuche.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                buttonSuche_ActionPerformed(e);

            }

        });
        buttonSuche.setBounds(24, 172, 97, 25);
        add(buttonSuche);

        model = new DefaultListModel<String>();
        list = new JList<String>(model);
        list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
        list.setLayoutOrientation(JList.VERTICAL_WRAP);
        list.setBounds(163, 51, 136, 196);
        add(list);

        buttonZuweisen = new JButton("Zuweisen");
        buttonZuweisen.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                buttonZuweisen_ActionPerformed(e);
            }

        });
        buttonZuweisen.setFont(new Font("Arial", Font.PLAIN, 20));
        buttonZuweisen.setBounds(338, 220, 127, 25);
        add(buttonZuweisen);
        setVisible(false);
    }

    public void buttonSuche_ActionPerformed(ActionEvent e) {
        List<Tutor> tmp = nv.searchSubject(new Subject(textField.getText())).getAllTeacher();
        tmp.toFirst();
        while(tmp.hasAccess()) {
        model.addElement(tmp.getContent().getForename() + " " + tmp.getContent().getSurname());
        tmp.next();
        }
    }

    public void buttonZuweisen_ActionPerformed(ActionEvent e) {
        int index = list.getSelectedIndex();

        String t = list.getModel().getElementAt(index);
        String[] splitted = t.split(" ");
        nv.searchSubject(new Subject(textField.getText())).searchTutor(splitted[0], splitted[1])
        .erhoeheBuchung(nv.searchStudent(new Student(lblNewLabel_2.getText(),lblNewLabel_1.getText())));;


    }
}


PanelVerwaltung

public class PanelVerwaltung extends JPanel {
    private NachhilfeVerwaltung nv;


    public PanelVerwaltung(NachhilfeVerwaltung pNv) {
        nv = pNv;

        btnNewButton = new JButton("Neuer Sch\u00FCler");
        btnNewButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                btnNewButton_ActionPerformed(e);
            }
        });
        btnNewButton.setBounds(30, 83, 116, 25);
        add(btnNewButton);



        buttonLoeschen = new JButton("L\u00F6schen");
        buttonLoeschen.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                buttonLoeschen_ActionPerformed(e);
            }
        });
        buttonLoeschen.setBounds(30, 305, 116, 25);
        add(buttonLoeschen);

        btnNewButton_1 = new JButton("Neuer Lehrer");
        btnNewButton_1.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                btnNewButton_1_ActionPerformed(e);
            }
        });
        btnNewButton_1.setBounds(212, 83, 128, 25);
        add(btnNewButton_1);

        btnNewButton_2 = new JButton("L\u00F6schen");
        btnNewButton_2.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
            btnNewButton_2_ActionPerformed(e);
            }
        });
        btnNewButton_2.setBounds(212, 305, 128, 25);
        add(btnNewButton_2);

        btnNewButton_3 = new JButton("Neues Fach");
        btnNewButton_3.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                btnNewButton_3_ActionPerformed(e);
            }

        });
        btnNewButton_3.setBounds(403, 202, 116, 25);
        add(btnNewButton_3);

        btnNewButton_4 = new JButton("L\u00F6schen");
        btnNewButton_4.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                btnNewButton_4_ActionPerformed(e);
            }

        });
        btnNewButton_4.setBounds(403, 255, 116, 25);
        add(btnNewButton_4);
        setVisible(false);

    }
    //Fach
    public void btnNewButton_4_ActionPerformed(ActionEvent e) {
        nv.removeSubject(new Subject(txtFachname.getText()));
    }
    public void btnNewButton_3_ActionPerformed(ActionEvent e) {
        nv.addSubject(new Subject(txtFachname.getText()));
    }

    //Lehrer
    public void btnNewButton_1_ActionPerformed(ActionEvent e) {
        GUINewTutor guiTutor = new GUINewTutor(nv);
        guiTutor.setVisible(true);

    }
    public void btnNewButton_2_ActionPerformed(ActionEvent e) {
        List<Subject> tmp = nv.getAllSubjects();
        tmp.toFirst();
        while(tmp.hasAccess()) {
            List<Tutor> tutorTMP = tmp.getContent().getAllTeacher();
            tutorTMP.toFirst();
            while(tutorTMP.hasAccess()) {
                if(tutorTMP.getContent().getForename().equalsIgnoreCase(txtVorname_1.getText()) &&
                   tutorTMP.getContent().getSurname().equalsIgnoreCase(txtNachname_1.getText())) {
                    tutorTMP.remove();
                }
            }
        }
    }

    //Student
    public void btnNewButton_ActionPerformed(ActionEvent evt) {
        GUINewStudent guiStudent = new GUINewStudent(nv);
        guiStudent.setVisible(true);

      }
    public void buttonLoeschen_ActionPerformed(ActionEvent evt) {
            nv.removeStudent(new Student(txtVorname.getText(),txtNachname.getText()));
      }
}