Can some one help me with this problem with my frame???

Question

i have gt a veri strange problem with my program,that is teh graphic changes only when i resize the the frame,if i dun resize,it will remain the same.However what i intended is that when i click on the radio button,it will change immediately to the respective pages.A simple version of my code is below,can someone helpl me solve it??(there is 3 different class)
import java.awt.event.*;
import javax.swing.*;
public class MainPg extends JFrame implements ActionListener{
     private javax.swing.JPanel jContentPane = null;
     private javax.swing.JPanel buttons = null;
     private javax.swing.JRadioButton one = null;
     private javax.swing.JRadioButton two = null;
     private javax.swing.JPanel change = null;
     public MainPg() {
          super();
          initialize();
     private void initialize() {
          this.setSize(300, 200);
          this.setContentPane(getJContentPane());
          this.setName("mainClass");
          this.setVisible(true);
     private javax.swing.JPanel getJContentPane() {
          if (jContentPane == null) {
               jContentPane = new javax.swing.JPanel();
               jContentPane.setLayout(new java.awt.BorderLayout());
               jContentPane.add(getButtons(), java.awt.BorderLayout.WEST);
               jContentPane.add(getChange(), java.awt.BorderLayout.CENTER);
          return jContentPane;
     private javax.swing.JPanel getButtons() {
          if(buttons == null) {
               buttons = new javax.swing.JPanel();
               java.awt.GridLayout layGridLayout1 = new java.awt.GridLayout();
               layGridLayout1.setRows(2);
               layGridLayout1.setColumns(1);
               ButtonGroup group=new ButtonGroup();
               group.add(getOne());
               group.add(getTwo());
               buttons.setLayout(layGridLayout1);
               buttons.add(getOne(), null);
               buttons.add(getTwo(), null);
          return buttons;
     private javax.swing.JRadioButton getOne() {
          if(one == null) {
               one = new javax.swing.JRadioButton();
               one.setText("One");
               one.setSelected(true);
               one.addActionListener(this);
               one.setActionCommand("one");
          return one;
     private javax.swing.JRadioButton getTwo() {
          if(two == null) {
               two = new javax.swing.JRadioButton();
               two.setText("Two");
               two.addActionListener(this);
               two.setActionCommand("two");
          return two;
     private javax.swing.JPanel getChange() {
          if(change == null) {
               change = new javax.swing.JPanel();
          change.add(new One());
          return change;
     public static void main(String[] args){
          new MainPg();
     public void actionPerformed(ActionEvent e) {
          change.removeAll();
          if("one".equals(e.getActionCommand())){
               change.add(new One());
          else{
               change.add(new Two());
          change.repaint();
import javax.swing.*;
public class One extends JPanel {
     private javax.swing.JPanel jPanel = null;
     private javax.swing.JLabel jLabel = null;
     private javax.swing.JPanel jPanel1 = null;
     private javax.swing.JLabel jLabel1 = null;
     private javax.swing.JLabel jLabel2 = null;
     public One() {
          super();
          initialize();
     * This method initializes this
     * @return void
     private void initialize() {
          this.setLayout(new java.awt.BorderLayout());
          this.add(getJPanel(), java.awt.BorderLayout.NORTH);
          this.add(getJPanel1(), java.awt.BorderLayout.WEST);
          this.setSize(300, 200);
     * This method initializes jPanel
     * @return javax.swing.JPanel
     private javax.swing.JPanel getJPanel() {
          if(jPanel == null) {
               jPanel = new javax.swing.JPanel();
               jPanel.add(getJLabel(), null);
          return jPanel;
     * This method initializes jLabel
     * @return javax.swing.JLabel
     private javax.swing.JLabel getJLabel() {
          if(jLabel == null) {
               jLabel = new javax.swing.JLabel();
               jLabel.setText("one");
          return jLabel;
     * This method initializes jPanel1
     * @return javax.swing.JPanel
     private javax.swing.JPanel getJPanel1() {
          if(jPanel1 == null) {
               jPanel1 = new javax.swing.JPanel();
               java.awt.GridLayout layGridLayout2 = new java.awt.GridLayout();
               layGridLayout2.setRows(2);
               layGridLayout2.setColumns(1);
               jPanel1.setLayout(layGridLayout2);
               jPanel1.add(getJLabel2(), null);
               jPanel1.add(getJLabel1(), null);
          return jPanel1;
     * This method initializes jLabel1
     * @return javax.swing.JLabel
     private javax.swing.JLabel getJLabel1() {
          if(jLabel1 == null) {
               jLabel1 = new javax.swing.JLabel();
               jLabel1.setText("one");
          return jLabel1;
     * This method initializes jLabel2
     * @return javax.swing.JLabel
     private javax.swing.JLabel getJLabel2() {
          if(jLabel2 == null) {
               jLabel2 = new javax.swing.JLabel();
               jLabel2.setText("one");
          return jLabel2;
import javax.swing.*;
public class Two extends JPanel {
     private javax.swing.JLabel jLabel = null;
     public Two() {
          super();
          initialize();
     * This method initializes this
     * @return void
     private void initialize() {
          this.setLayout(new java.awt.FlowLayout());
          this.add(getJLabel(), null);
          this.setSize(300, 200);
     * This method initializes jLabel
     * @return javax.swing.JLabel
     private javax.swing.JLabel getJLabel() {
          if(jLabel == null) {
               jLabel = new javax.swing.JLabel();
               jLabel.setText("two");
          return jLabel;
}

Answer 1

//change.repaint();
change.revalidate();