After exporting project to jar file, my project is not fully working

i have a problem that in Eclipse when i run my project everything is working fine but when i exporting it last class don’t want to open by clicking the button. I’m using database in every class as well as i have referenced library(jcalendar-1.4) if it will help you to solve the problem. login and registration class are working fine and after logged in and transfer to addActivity class most thing are working like adding everything to database but that one button is unable to open that last class that should show all activities added.

code for AddActivity class and button that is not working in jar file is called txtAddActivity

AddActivity.java

package timeManager;

public class AddActivity {

    protected JFrame frmAddActiviti;

    private Login loginScreen = null;
    private Database database = null;
    private ShowActivities showActivities = null;

    private JTextField textActivityName;
    private JTextField txtLogoff;
    private JLabel lblNewLabel_1;
    private JLabel lblActivityDescription;
    private JTextField txtAddActivity;
    private JTextField txtShowActivitis;
    private JTextArea textArea;

    private JDateChooser dateChooser;
    private String login = "";
    private String password = "";
    private String deadline = "";
    private Date date;
    private JLabel lblErrorMessage;
    private JLabel lblErrorMessage2;
    private JLabel lblErrorMessage3;

    /**
     * Create the application.
     */
    public AddActivity() {
        gui();
    }

    public AddActivity(String login, String password) {
        this.login = login;
        this.password = password;
        gui();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void gui() {
        frmAddActiviti = new JFrame();
        frmAddActiviti.setTitle("Add Activity");
        frmAddActiviti.setSize(450, 300);
        frmAddActiviti.setResizable(false);
        frmAddActiviti.setLocationRelativeTo(null);
        frmAddActiviti.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmAddActiviti.getContentPane().setLayout(null);

        JPanel panel = new JPanel();
        panel.setBackground(new Color(128, 128, 128));
        panel.setBounds(0, 0, 434, 261);
        frmAddActiviti.getContentPane().add(panel);
        panel.setLayout(null);

        JLabel lblNewLabel = new JLabel("Welcome, " + login);
        lblNewLabel.setBorder(new LineBorder(new Color(255, 255, 255), 3, true));
        lblNewLabel.setFont(new Font("Tahoma", Font.BOLD, 14));
        lblNewLabel.setForeground(new Color(255, 255, 255));
        lblNewLabel.setHorizontalAlignment(SwingConstants.CENTER);
        lblNewLabel.setBounds(26, 11, 224, 25);
        panel.add(lblNewLabel);

        textActivityName = new JTextField();
        textActivityName.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        textActivityName.setBounds(26, 64, 224, 20);
        panel.add(textActivityName);
        textActivityName.setColumns(10);

        textArea = new JTextArea();
        textArea.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        textArea.setBounds(26, 112, 224, 57);
        panel.add(textArea);

        txtLogoff = new JTextField();
        txtLogoff.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {
                logoff();
            }
        });
        txtLogoff.setEditable(false);
        txtLogoff.setFont(new Font("Tahoma", Font.BOLD, 14));
        txtLogoff.setForeground(new Color(255, 255, 255));
        txtLogoff.setHorizontalAlignment(SwingConstants.CENTER);
        txtLogoff.setText("Sign out");
        txtLogoff.setBorder(new EtchedBorder(EtchedBorder.RAISED, null, null));
        txtLogoff.setBackground(new Color(128, 128, 128));
        txtLogoff.setBounds(273, 11, 92, 25);
        panel.add(txtLogoff);
        txtLogoff.setColumns(10);

        lblNewLabel_1 = new JLabel("Activity Name*");
        lblNewLabel_1.setFont(new Font("Tahoma", Font.BOLD, 12));
        lblNewLabel_1.setForeground(new Color(255, 255, 255));
        lblNewLabel_1.setHorizontalAlignment(SwingConstants.LEFT);
        lblNewLabel_1.setBounds(26, 47, 104, 14);
        panel.add(lblNewLabel_1);

        lblActivityDescription = new JLabel("Activity Description");
        lblActivityDescription.setHorizontalAlignment(SwingConstants.LEFT);
        lblActivityDescription.setForeground(Color.WHITE);
        lblActivityDescription.setFont(new Font("Tahoma", Font.BOLD, 12));
        lblActivityDescription.setBounds(26, 95, 138, 14);
        panel.add(lblActivityDescription);

        dateChooser = new JDateChooser();
        dateChooser.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        dateChooser.setBounds(260, 64, 119, 20);
        panel.add(dateChooser);

        txtAddActivity = new JTextField();
        txtAddActivity.setEditable(false);
        txtAddActivity.addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseMoved(MouseEvent arg0) {
                txtAddActivity.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
            }
        });
        txtAddActivity.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseExited(MouseEvent e) {
                txtAddActivity.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
            }

            @Override
            public void mouseClicked(MouseEvent e) {
                add();
            }
        });
        txtAddActivity.setFont(new Font("Tahoma", Font.BOLD, 12));
        txtAddActivity.setHorizontalAlignment(SwingConstants.CENTER);
        txtAddActivity.setText("Add activity");
        txtAddActivity.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
        txtAddActivity.setForeground(new Color(255, 255, 255));
        txtAddActivity.setBackground(new Color(128, 128, 128));
        txtAddActivity.setBounds(26, 192, 104, 25);
        panel.add(txtAddActivity);
        txtAddActivity.setColumns(10);

        JLabel lblDeadline = new JLabel("Deadline*");
        lblDeadline.setHorizontalAlignment(SwingConstants.LEFT);
        lblDeadline.setForeground(Color.WHITE);
        lblDeadline.setFont(new Font("Tahoma", Font.BOLD, 12));
        lblDeadline.setBounds(260, 47, 104, 14);
        panel.add(lblDeadline);

        txtShowActivitis = new JTextField();
        txtShowActivitis.setEditable(false);
        txtShowActivitis.addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseMoved(MouseEvent arg0) {
                txtShowActivitis.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
            }
        });
        txtShowActivitis.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseExited(MouseEvent e) {
                txtShowActivitis.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
            }

            @Override
            public void mouseClicked(MouseEvent e) {
                show();
            }
        });
        txtShowActivitis.setText("Show activities");
        txtShowActivitis.setHorizontalAlignment(SwingConstants.CENTER);
        txtShowActivitis.setForeground(Color.WHITE);
        txtShowActivitis.setFont(new Font("Tahoma", Font.BOLD, 12));
        txtShowActivitis.setColumns(10);
        txtShowActivitis.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
        txtShowActivitis.setBackground(Color.GRAY);
        txtShowActivitis.setBounds(146, 192, 104, 25);
        panel.add(txtShowActivitis);

        lblErrorMessage = new JLabel("");
        lblErrorMessage.setFont(new Font("Tahoma", Font.PLAIN, 11));
        lblErrorMessage.setForeground(new Color(128, 0, 0));
        lblErrorMessage.setBounds(26, 72, 398, 36);
        panel.add(lblErrorMessage);

        lblErrorMessage2 = new JLabel("");
        lblErrorMessage2.setForeground(new Color(128, 0, 0));
        lblErrorMessage2.setFont(new Font("Tahoma", Font.PLAIN, 11));
        lblErrorMessage2.setBounds(26, 161, 398, 36);
        panel.add(lblErrorMessage2);

        lblErrorMessage3 = new JLabel("");
        lblErrorMessage3.setForeground(Color.GREEN);
        lblErrorMessage3.setFont(new Font("Tahoma", Font.PLAIN, 11));
        lblErrorMessage3.setBounds(26, 208, 398, 36);
        panel.add(lblErrorMessage3);

    }

    private void logoff() {
        loginScreen = new Login();
        loginScreen.frmLogin.setVisible(true);
        frmAddActiviti.setVisible(false);
    }

    private void add() {
        String activityName = "";
        String activityDescription = "";
        boolean activityNameCorrect = true;
        boolean descriptionCorrect = true;
        boolean dateAccepted = true;
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");

        lblErrorMessage3.setText("");

        activityName = textActivityName.getText();
        activityDescription = textArea.getText();

        try {
            if (!(Character.isUpperCase(activityName.charAt(0)) && activityName.length() > 1)) {
                activityNameCorrect = false;
                lblErrorMessage
                        .setText("Activity name need to start with capital letter and have at least 2 characters");
            } else {
                lblErrorMessage.setText("");
            }
        } catch (Exception ex) {
            activityNameCorrect = false;
            lblErrorMessage.setText("Activity name need to start with capital letter and have at least 2 characters");
            System.out.println(ex);
        }

        try {
            int counterWords = 0;
            for (int i = 0; i < activityDescription.length(); i++) {
                if (activityDescription.charAt(i) == ' ') {
                    counterWords++;
                }
            }
            if (counterWords > 20) {
                descriptionCorrect = false;
                lblErrorMessage2.setText("you cant have more than 20 words in description");
            }
        } catch (Exception ex) {
            System.out.println(ex);
        }

        if (activityNameCorrect == true) {
            // gettign today's date
            date = new Date();
            String todayDate = dateFormat.format(date);

            try {
                // checking if chosen date is earlier than today's one
                deadline = dateFormat.format(dateChooser.getDate());
                if (todayDate.compareTo(deadline) > 0) {
                    lblErrorMessage.setText("You cant choose date earlier than today's date");
                    dateAccepted = false;
                }
            } catch (Exception ex) {
                dateAccepted = false;
                lblErrorMessage.setText("You need to pick the date");
                System.out.println(ex);
            }
        }

        if (activityNameCorrect == true && dateAccepted == true && descriptionCorrect == true) {
            boolean originalActivityName = false;
            database = new Database(activityName, login, 0);
            originalActivityName = database.getOriginalName();
            if (originalActivityName == true) {
                try {
                    date = dateFormat.parse(deadline);

                } catch (Exception ex) {
                    System.out.println(ex);
                }
                database = new Database(activityName, activityDescription, date, login, password);
                lblErrorMessage3.setText("Activity added!");
            } else {
                lblErrorMessage3.setText("");
                lblErrorMessage2.setText("This activity name already exist");
            }
        }
    }

    private void show() {
        showActivities = new ShowActivities(login, password);
        showActivities.frmShowActivities.setVisible(true);
        frmAddActiviti.setVisible(false);
    }
}

code for ShowActivities that is not displaying in jar file

ShowActivities.java

package timeManager;

public class ShowActivities {

    protected JFrame frmShowActivities;

    private Login loginScreen = null;
    private AddActivity addActivity = null;
    private Database database = null;

    private String login, password;

    private String[] activityNames = new String[100];
    private String[] activityDescriptions = new String[100];
    private String[] deadlines = new String[100];
    private int[] counters = { 0, 1 };
    private int activitiesCount;

    private JTextField txtLogoff, txtAddNewActivity;
    private JLabel lblActivityName, lblActivityDeadline, lblActivityName2, lblActivityDeadline2;
    private JTextArea textArea, textArea2;

    /**
     * Create the application.
     */
    public ShowActivities() {
        initialize();
    }

    public ShowActivities(String login, String password) {
        this.login = login;
        this.password = password;
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frmShowActivities = new JFrame();
        frmShowActivities.setResizable(false);
        frmShowActivities.setTitle("Show Activities");
        frmShowActivities.setSize(536, 345);
        frmShowActivities.setLocationRelativeTo(null);
        frmShowActivities.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frmShowActivities.getContentPane().setLayout(null);

        getAllUserActivity();

        JPanel panel = new JPanel();
        panel.setBackground(new Color(128, 128, 128));
        panel.setBounds(0, 0, 546, 342);
        frmShowActivities.getContentPane().add(panel);
        panel.setLayout(null);

        JPanel panel_1 = new JPanel();
        panel_1.setBackground(new Color(105, 105, 105));
        panel_1.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        panel_1.setBounds(187, 11, 308, 143);
        panel.add(panel_1);
        panel_1.setLayout(null);

        JLabel lblNewLabel_1 = new JLabel("Activity Name:");
        lblNewLabel_1.setHorizontalAlignment(SwingConstants.RIGHT);
        lblNewLabel_1.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblNewLabel_1.setForeground(new Color(255, 255, 255));
        lblNewLabel_1.setBounds(5, 5, 114, 14);
        panel_1.add(lblNewLabel_1);

        lblActivityName = new JLabel("");
        lblActivityName.setText(activityNames[counters[0]]);
        lblActivityName.setForeground(new Color(255, 255, 255));
        lblActivityName.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblActivityName.setBounds(123, 5, 175, 14);
        panel_1.add(lblActivityName);

        JLabel lblNewLabel_3 = new JLabel("Activity Description:");
        lblNewLabel_3.setHorizontalAlignment(SwingConstants.RIGHT);
        lblNewLabel_3.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblNewLabel_3.setForeground(new Color(255, 255, 255));
        lblNewLabel_3.setBounds(5, 47, 114, 14);
        panel_1.add(lblNewLabel_3);

        textArea = new JTextArea();
        textArea.setText(activityDescriptions[counters[0]]);
        textArea.setEditable(false);
        textArea.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        textArea.setBounds(123, 45, 175, 90);
        panel_1.add(textArea);

        JLabel lblDeadline = new JLabel("Deadline:");
        lblDeadline.setHorizontalAlignment(SwingConstants.RIGHT);
        lblDeadline.setForeground(Color.WHITE);
        lblDeadline.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblDeadline.setBounds(5, 25, 114, 14);
        panel_1.add(lblDeadline);

        lblActivityDeadline = new JLabel("");
        lblActivityDeadline.setText(deadlines[counters[0]]);
        lblActivityDeadline.setForeground(Color.WHITE);
        lblActivityDeadline.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblActivityDeadline.setBounds(123, 25, 175, 14);
        panel_1.add(lblActivityDeadline);

        JLabel lblComplete = new JLabel("");
        lblComplete.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                removeActivity(0);
            }
        });
        lblComplete.setIcon(new ImageIcon("C:\Users\jakub\OneDrive\Desktop\Done.png"));
        lblComplete.setBounds(40, 85, 50, 50);
        panel_1.add(lblComplete);

        JLabel lblNewLabel_2 = new JLabel("Activity Completed?");
        lblNewLabel_2.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblNewLabel_2.setForeground(new Color(255, 255, 255));
        lblNewLabel_2.setBounds(5, 69, 114, 14);
        panel_1.add(lblNewLabel_2);

        JLabel lblNewLabel = new JLabel("");
        lblNewLabel.setBounds(-175, 30, 161, 212);
        panel_1.add(lblNewLabel);
        lblNewLabel.setIcon(new ImageIcon("C:\Users\jakub\OneDrive\Desktop\stock-going-up-png.png"));

        JLabel lblUP = new JLabel("");
        lblUP.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                moveUP();
            }
        });
        lblUP.setIcon(new ImageIcon(ShowActivities.class
                .getResource("/com/sun/javafx/scene/control/skin/caspian/dialog-fewer-details.png")));
        lblUP.setBounds(502, 11, 21, 21);
        panel.add(lblUP);

        JLabel lblDOWN = new JLabel("");
        lblDOWN.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                moveDown();
            }
        });
        lblDOWN.setIcon(new ImageIcon(ShowActivities.class
                .getResource("/com/sun/javafx/scene/control/skin/caspian/dialog-more-details.png")));
        lblDOWN.setBounds(502, 275, 21, 21);
        panel.add(lblDOWN);

        JPanel panel_2 = new JPanel();
        panel_2.setLayout(null);
        panel_2.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        panel_2.setBackground(SystemColor.controlDkShadow);
        panel_2.setBounds(187, 155, 308, 143);
        panel.add(panel_2);

        JLabel label = new JLabel("Activity Name:");
        label.setHorizontalAlignment(SwingConstants.RIGHT);
        label.setForeground(Color.WHITE);
        label.setFont(new Font("Tahoma", Font.BOLD, 11));
        label.setBounds(5, 5, 114, 14);
        panel_2.add(label);

        lblActivityName2 = new JLabel("");
        lblActivityName2.setText(activityNames[counters[1]]);
        lblActivityName2.setForeground(Color.WHITE);
        lblActivityName2.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblActivityName2.setBounds(123, 5, 175, 14);
        panel_2.add(lblActivityName2);

        JLabel label_2 = new JLabel("Activity Description:");
        label_2.setHorizontalAlignment(SwingConstants.RIGHT);
        label_2.setForeground(Color.WHITE);
        label_2.setFont(new Font("Tahoma", Font.BOLD, 11));
        label_2.setBounds(5, 47, 114, 14);
        panel_2.add(label_2);

        textArea2 = new JTextArea();
        textArea2.setText(activityDescriptions[counters[1]]);
        textArea2.setEditable(false);
        textArea2.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
        textArea2.setBounds(123, 45, 175, 90);
        panel_2.add(textArea2);

        JLabel label_3 = new JLabel("Deadline:");
        label_3.setHorizontalAlignment(SwingConstants.RIGHT);
        label_3.setForeground(Color.WHITE);
        label_3.setFont(new Font("Tahoma", Font.BOLD, 11));
        label_3.setBounds(5, 25, 114, 14);
        panel_2.add(label_3);

        lblActivityDeadline2 = new JLabel("");
        lblActivityDeadline2.setText(deadlines[counters[1]]);
        lblActivityDeadline2.setForeground(Color.WHITE);
        lblActivityDeadline2.setFont(new Font("Tahoma", Font.BOLD, 11));
        lblActivityDeadline2.setBounds(123, 25, 175, 14);
        panel_2.add(lblActivityDeadline2);

        JLabel lblComplete2 = new JLabel("");
        lblComplete2.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                removeActivity(1);
            }
        });
        lblComplete2.setIcon(new ImageIcon("C:\Users\jakub\OneDrive\Desktop\Done.png"));
        lblComplete2.setBounds(40, 85, 50, 50);
        panel_2.add(lblComplete2);

        JLabel label_6 = new JLabel("Activity Completed?");
        label_6.setForeground(Color.WHITE);
        label_6.setFont(new Font("Tahoma", Font.BOLD, 11));
        label_6.setBounds(5, 69, 114, 14);
        panel_2.add(label_6);

        txtLogoff = new JTextField();
        txtLogoff.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                logoff();
            }
        });
        txtLogoff.setText("Sign out");
        txtLogoff.setHorizontalAlignment(SwingConstants.CENTER);
        txtLogoff.setForeground(Color.WHITE);
        txtLogoff.setFont(new Font("Tahoma", Font.BOLD, 14));
        txtLogoff.setEditable(false);
        txtLogoff.setColumns(10);
        txtLogoff.setBorder(new EtchedBorder(EtchedBorder.RAISED, null, null));
        txtLogoff.setBackground(Color.GRAY);
        txtLogoff.setBounds(40, 11, 92, 25);
        panel.add(txtLogoff);

        txtAddNewActivity = new JTextField();
        txtAddNewActivity.addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseMoved(MouseEvent arg0) {
                txtAddNewActivity.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null));
            }
        });
        txtAddNewActivity.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent e) {
                callAddActivity();
            }

            @Override
            public void mouseExited(MouseEvent e) {
                txtAddNewActivity.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
            }
        });
        txtAddNewActivity.setText("Add new activity");
        txtAddNewActivity.setHorizontalAlignment(SwingConstants.CENTER);
        txtAddNewActivity.setForeground(Color.WHITE);
        txtAddNewActivity.setFont(new Font("Tahoma", Font.BOLD, 12));
        txtAddNewActivity.setEditable(false);
        txtAddNewActivity.setColumns(10);
        txtAddNewActivity.setBorder(new BevelBorder(BevelBorder.RAISED, null, null, null, null));
        txtAddNewActivity.setBackground(Color.GRAY);
        txtAddNewActivity.setBounds(30, 270, 120, 25);
        panel.add(txtAddNewActivity);

        JLabel lblNewLabel_4 = new JLabel("");
        lblNewLabel_4.setIcon(new ImageIcon("C:\Users\jakub\OneDrive\Desktop\graphs.png"));
        lblNewLabel_4.setBounds(10, 47, 167, 212);
        panel.add(lblNewLabel_4);
    }

    private void callAddActivity() {
        addActivity = new AddActivity(login, password);
        addActivity.frmAddActiviti.setVisible(true);
        frmShowActivities.setVisible(false);
    }

    private void logoff() {
        loginScreen = new Login();
        loginScreen.frmLogin.setVisible(true);
        frmShowActivities.setVisible(false);
    }

    /**
     * sort from smallest date to biggest
     */
    private void sortActivitiesInOrder() {
        String[] temp = new String[3];
        for (int i = 0; i < (activitiesCount - 1); i++) {
            for (int j = 0; j < (activitiesCount - 1); j++) {
                if (deadlines[j].compareTo(deadlines[j + 1]) > 0) {
                    temp[0] = deadlines[j];
                    temp[1] = activityNames[j];
                    temp[2] = activityDescriptions[j];
                    deadlines[j] = deadlines[j + 1];
                    activityNames[j] = activityNames[j + 1];
                    activityDescriptions[j] = activityDescriptions[j + 1];
                    deadlines[j + 1] = temp[0];
                    activityNames[j + 1] = temp[1];
                    activityDescriptions[j + 1] = temp[2];
                }
            }
        }
    }

    /**
     * getting all activities for a user
     */
    private void getAllUserActivity() {
        database = new Database(login, activityNames, activityDescriptions, deadlines);
        activityNames = database.getActivityNames();
        activityDescriptions = database.getActivityDescriptions();
        deadlines = database.getDeadlines();
        activitiesCount = database.getCounter();
        sortActivitiesInOrder();
    }

    private void removeActivity(int i) {
        database = new Database(login, password, activityNames[counters[i]], activityDescriptions[counters[i]],
                deadlines[counters[i]]);
        activityNames = new String[100];
        activityDescriptions = new String[100];
        deadlines = new String[100];
        getAllUserActivity();
        setActivitiesTexts();
    }

    private void moveDown() {
        activitiesCount = database.getCounter();
        if (counters[1] < (activitiesCount - 1)) {
            counters[0]++;
            counters[1]++;
            setActivitiesTexts();
        }
    }

    private void moveUP() {
        if (counters[0] > 0) {
            counters[0]--;
            counters[1]--;
            setActivitiesTexts();
        }
    }

    private void setActivitiesTexts() {
        lblActivityName.setText(activityNames[counters[0]]);
        lblActivityName2.setText(activityNames[counters[1]]);
        textArea.setText(activityDescriptions[counters[0]]);
        textArea2.setText(activityDescriptions[counters[1]]);
        lblActivityDeadline.setText(deadlines[counters[0]]);
        lblActivityDeadline2.setText(deadlines[counters[1]]);
    }

}

Answer

Changing from Eclipse to NetBeans fixed the issue as jar file exported from netBeans worked perfectly fine