Best way to add and remove JPanels?

Question

I have a question on the best practice in removing and then adding JPanels. I know a few ways about doing it but it never seems to work just how I want it to. Any help would be great. Also if anyone wants to give tips on better ways of writing this code I am out your any ideas.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.*;
class test2 extends JFrame implements ActionListener {
    private static final int FRAME_WIDTH    = 575;
    private static final int FRAME_HEIGHT   = 500;
    private static final int FRAME_X_ORIGIN = 150;
    private static final int FRAME_Y_ORIGIN = 250;
    //jbutton
    String [] foodButton = {"Tofu Burger",   "Cajun Chicken",
                            "Buffalo Wings", "Rainbow Fillet",
                            "Rice Cracker",  "No Salt Fries",
                            "Zucchini",      "Brown Rice",
                            "Cafe Mocha",    "Cafe Latte",
                            "Espresso",      "Oolong Tea"};
    JButton b[]          = new JButton[foodButton.length];
    JButton orderButton  = new JButton("Order");
    JButton cancelButton = new JButton("Cancel");
    JButton backButton   = new JButton("Back");
    int [] foodCount     = new int [12];
    double [] foodCost   = {3.49, 4.59,
                            3.99, 2.99,
                            0.79, 0.69,
                            1.09, 0.59,
                            1.99, 1.99,
                            2.49, 0.99};
    double subtotal;
    JPanel outPut         = new JPanel();
    JLabel test           = new JLabel ("Subtotal: ");
    //constructor
    public test2() {
        setContentPane(outPut);
        foodButton();
        frame();
        setVisible(true);
    //frame
    public void frame() {
        setSize(FRAME_WIDTH, FRAME_HEIGHT);
        setResizable(true);
        setTitle("Welcome to Low Fat Burger");
        setLocation(FRAME_X_ORIGIN, FRAME_Y_ORIGIN);
    //button builder
    public void foodButton() {
        ImageIcon myIcon = new ImageIcon("C:/Documents and Settings/Keith/My Documents/My Pictures/Clip Art/lowFatBurger.jpg");
        JPanel header    = new JPanel();
        JPanel menu      = new JPanel();
        JPanel bottom    = new JPanel();
        JPanel subtotal  = new JPanel();
        JPanel itemCount = new JPanel();
        JPanel control   = new JPanel();
        outPut.setLayout(new BorderLayout(0, 0));
        //outPut.setBorder(BorderFactory.createLineBorder(Color.red));
        outPut.add(header,   BorderLayout.NORTH);
        outPut.add(menu,     BorderLayout.CENTER);
        outPut.add(bottom,   BorderLayout.SOUTH);
        header.setLayout(new FlowLayout(FlowLayout.CENTER, 5, 5));
        header.add(new JLabel(myIcon));
        menu.setLayout(new GridLayout(4, 3));
        //test.setLayout(new FlowLayout());
        //test.setBorder(BorderFactory.createLineBorder(Color.red));
        for(int i=0; i<foodButton.length; i++) {
            b[i] = new JButton (foodButton);
//work area
b[i].addActionListener(this);
menu.add(b[i]);
//add actionlistener to control buttons
orderButton.addActionListener(this);
cancelButton.addActionListener(this);
backButton.addActionListener(this);
bottom.setLayout(new BorderLayout(0, 0));
bottom.add(subtotal, BorderLayout.NORTH);
bottom.add(itemCount, BorderLayout.CENTER);
bottom.add(control, BorderLayout.SOUTH);
subtotal.add(test);
control.add(orderButton);
control.add(cancelButton);
public void actionPerformed(ActionEvent event) {
String straction = event.getActionCommand();
//format
DecimalFormat df = new DecimalFormat("0.00");
for(int j=0; j<foodButton.length; j++) {;
if(event.getSource() == b[j]) {
int count = ++foodCount[j];
double itemSubtotal = count * foodCost[j];
for(int i=0; i<foodButton.length; i++) {
subtotal = (foodCount[i] * foodCost[i]);
test.setText("Subtotal: $" + df.format(subtotal));
if(straction.equals("Cancel")) {
}else if(straction.equals("Order")) {
//menu.removeAll();
//control.removeAll();
//control.add(orderButton);
//control.add(backButton);
//menu.revalidate();
//menu.repaint();
}else if(straction.equals("Back")) {
public static void main (String[] args) {
new test();

Answer 1

If you want a really cheap way to go about it, you could try setVisible(false) instead of removing the panel. It will result in the same visual effect, and if you ever need to add the component back, you just need to setVisible(true) again.
But make sure you do it inside the event loop...
SwingUtilities.invokeLater(new Runnable() {
    public void run() {
        panel.setVisible(false);
});