public Task15Form(Task15 task15) {
        this.task15 = task15;
        setContentPane(rootPanel);
        pack();
        setSize(800, 300);
        setVisible(true);

        addTextField.addKeyListener(new KeyAdapter() {
            @Override
            public void keyReleased(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    Double v;
                    try {
                        v = Double.parseDouble(addTextField.getText());
                    } catch (NumberFormatException e1) {
                        e1.printStackTrace();
                        return;
                    }
                    task15.add(v);
                    addTextField.setText("");
                    updateTextArea();

                }
            }
        });

        deleteTextField.addKeyListener(new KeyAdapter() {
            @Override
            public void keyReleased(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    Double v;
                    try {
                        v = Double.parseDouble(deleteTextField.getText());
                    } catch (NumberFormatException e1) {

                        return;
                    }
                    task15.delete(v);
                    deleteTextField.setText("");
                    updateTextArea();

                }
            }
        });

        findTextField.addKeyListener(new KeyAdapter() {
            @Override
            public void keyReleased(KeyEvent e) {
                if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                    Double v;
                    try {
                        v = Double.parseDouble(findTextField.getText());
                    } catch (NumberFormatException e1) {

                        return;
                    }
                    Double aDouble = task15.find(v);
                    resultFindLabel.setText(aDouble.toString());
                }
            }
        });
    }