Membuat format input angka Ribuan di Java Swing

import javax.swing.*;
import javax.swing.text.MaskFormatter;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
 
/**
 * Created with IntelliJ IDEA.
 * Author: Lee
 * Date: 5/20/2014
 * Time: 1:50 PM
 * To change this template use File | Settings | File Templates.
 */
public class NumberTextField extends JTextField {
    private char separator = '.';
 
    public NumberTextField(){
        super();
        setHorizontalAlignment(SwingConstants.RIGHT);
        setText("0");
        addFocusListener(new FocusAdapter() {
            @Override
            public void focusGained(FocusEvent focusEvent) {
                NumberTextField.super.setText(getText());
                NumberTextField.super.selectAll();
            }
 
            @Override
            public void focusLost(FocusEvent e){
                setText(NumberTextField.super.getText());
            }
        });
        addKeyListener(new KeyAdapter() {
            @Override
            public void keyTyped(KeyEvent e) {
                char c = e.getKeyChar();
                if (!((c >= '0') && (c <= '9') ||
                        (c == KeyEvent.VK_BACK_SPACE) ||
                        (c == KeyEvent.VK_DELETE))) {
                    getToolkit().beep();
                    e.consume();
                }
            }
        });
        // */
    }
 
    public void setSeparator(char s){
        separator = s;
    }
 
    @Override
    public void setText(String s){
        super.setText(formatNumber(s));
    }
 
    @Override
    public String getText() {
        String s = super.getText();
        return s.replaceAll("[^0-9]", "");
    }
 
    public String getNumberFormattedText(){
        return super.getText();
    }
 
    public String formatNumber(String s){
        try {
            int v = Integer.parseInt(s);
            return String.format("%,d", v).replace(",", separator + "");
        } catch (Exception e) {
            return "0";
        }
    }
    // */
}

import sun.awt.HorizBagLayout;
 
import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
/**
 * Created with IntelliJ IDEA.
 * User: lee
 * Date: 6/22/14
 * Time: 1:01 PM
 */
public class Main {
    public static void main(String[] args){
        try{
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e){
 
        }
 
        final JFrame f = new JFrame();
        f.setTitle("Number Formatted Input Field");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setMinimumSize(new Dimension(400, 100));
 
        final JPanel body = new JPanel();
        body.setLayout(new BoxLayout(body, BoxLayout.Y_AXIS));
        body.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
        f.getContentPane().add(body, BorderLayout.CENTER);
 
        for(int i = 1; i <= 5; i++){
            JPanel p = new JPanel();
            p.setLayout(new BoxLayout(p, BoxLayout.X_AXIS));
            p.add(new JLabel("Input " + i));
            p.add(Box.createHorizontalStrut(10));
 
            NumberTextField input = new NumberTextField();
            // misalnya diinginkan separator ribuan yang 'aneh';
//            input.setSeparator('-');
 
            p.add(input);
            body.add(p);
            body.add(Box.createVerticalStrut(5));
        }
 
        JButton b = new JButton("Lihat Input");
        b.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent actionEvent) {
                String res = "", temp;
                for(int i = 1; i <= 10; i++){
                    if( i % 2 == 0) continue;
                    JPanel p;
                    try{
                        p = (JPanel) body.getComponent(i - 1);
                    } catch (Exception e){
                        System.out.println("Error: " + i);
                        e.printStackTrace();
                        continue;
                    }
 
                    temp = String.format("input ke %s diisi %s = %s \n", (i / 2) + 1,
                            ((NumberTextField) p.getComponent(2)).getText(),
                            ((NumberTextField) p.getComponent(2)).getNumberFormattedText()
                    );;
                    if(res.equals("")){
                        res = temp;
                    } else {
                        res += temp;
                    }
                }
                JOptionPane.showMessageDialog(f, res);
            }
        });
        body.add(b);
 
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }
}