Randomly Generate Number then store in new JTextField

Pretty much what I want is when the number is randomly generated on the screen the next time the spin button is pushed it saves the previous number off to the side and so on.

Here is my current code for the spin button to generate the random number:

timer = new Timer(500, new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            StringBuilder sb = new StringBuilder(tNumber.getText());
            sb.append(values[index]);
            tNumber.setText(sb.toString());

            index++;
            if (index >= values.length) {
                ((Timer) e.getSource()).stop();
            }
        }
    });
    timer.setInitialDelay(500);
}

public void actionPerformed(ActionEvent e) {
    if (e.getSource() == b) {
        String s = tTo.getText();
        String t = tFrom.getText();
        try {
            int x = Integer.parseInt(t);
            int d = Integer.parseInt(s);
            if (x >= d) {
                JOptionPane
                        .showMessageDialog(f,
                                "START value is higher or Equal to END value, please enter a lower number...");
            } else if (timer.isRunning()) {
                timer.stop();
            }
            int newNumber = (int) (Math.random() * (d + 1 - x) + x);
            tNumber.setText("");
            index = 0;
            String text = Integer.toString(newNumber);
            values = text.toCharArray();
            timer.start();

        } catch (NumberFormatException ee) {
            JOptionPane
                    .showMessageDialog(f,
                            "You have entered an Invaild format please reconfigure...");

        }

    } else if (e.getSource() == bSave) {
        tTitle.setText(tName.getText());
    }
}

What would I need to add to generate a JTextField with the previous randomly generated number it.