Problemas serios com JFormatedTextField, um dilema!

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 
import javax.swing.text.MaskFormatter; 
import java.text.ParseException; 
/*mostra formatação para data e CPF*/
public class UITestMasc extends JFrame implements ActionListener { 
    
   JFormattedTextField fieldFormatado; 
    
   MaskFormatter mascDataNasc; 
   MaskFormatter mascCpf; 
    
   JButton btnData = new JButton("Data"); 
   JButton btnCpf = new JButton("CPF"); 
    
   public UITestMasc() { 
      super("Teste de JFormattedTextField"); 
      this.getContentPane().setLayout(null); 
      setBounds(100,100,250,150); 
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setLocationRelativeTo(null);//centraliza o JFrame na Tela
      try { 
         mascDataNasc = new MaskFormatter("##/##/####"); 
         mascDataNasc.setPlaceholderCharacter('_'); 
         fieldFormatado = new JFormattedTextField(mascDataNasc); 
         fieldFormatado.setBounds(30,30,100,20); 
         this.getContentPane().add(fieldFormatado, null); 
      } 
      catch (ParseException e) { 
         e.printStackTrace(); 
      } 
       
      btnData.setBounds(10,60,60,20); 
      btnData.addActionListener(this); 
      this.getContentPane().add(btnData, null); 
       
      btnCpf.setBounds(100,60,60,20); 
      btnCpf.addActionListener(this); 
      this.getContentPane().add(btnCpf, null); 
       
      show(); 
       
   } 
    
   public void actionPerformed(ActionEvent e) { 
      if(e.getSource() == btnData) { 
         try { 
            this.getContentPane().remove(fieldFormatado); 
            mascDataNasc = new MaskFormatter("##/##/####"); 
            mascDataNasc.setPlaceholderCharacter('_'); 
            fieldFormatado = new JFormattedTextField(mascDataNasc); 
            fieldFormatado.setBounds(30,30,100,20); 
            this.getContentPane().add(fieldFormatado, null); 
            show(); 
         } 
         catch (ParseException pe) { 
            pe.printStackTrace(); 
         } 
      } 
       
      if(e.getSource() == btnCpf) { 
         try { 
            this.getContentPane().remove(fieldFormatado); 
            mascCpf = new MaskFormatter("###.###.###.-##"); 
            mascCpf.setPlaceholderCharacter('_'); 
            fieldFormatado = new JFormattedTextField(mascCpf); 
            fieldFormatado.setBounds(30,30,100,20); 
            this.getContentPane().add(fieldFormatado, null); 
            show(); 
         } 
         catch (ParseException pe) { 
            pe.printStackTrace(); 
         } 
      } 
   } 
    
   public static void main(String[] args) { 
      new UITestMasc();    
   } 
    
}