card.next(yourPanel); will loop through all the components in your mainpanel then come to first one. To show a component with your own desire try following (think if there are 5 components and you are on the 2 and want to show first then you have to go through rest of all in the Vincent Ramdhanie s example, JRL s answer is good according to that gives a quick jump to one you want, but here is another way.

import javax.swing.JLabel;
import javax.swing.JPanel;

public class myJFrame extends javax.swing.JFrame {

    private JPanel panel1, panel2;
    /**
     * Creates new form myJFrame
     */
    public myJFrame() {
        initComponents();
        panel1=new JPanel();
        panel2=new JPanel();

        JLabel lb1=new JLabel("This is panel 1");
        JLabel lb2=new JLabel("This is panel 2");
        panel1.add(lb1);
        panel2.add(lb2);
//make more if you want
//        contentPanel.add(panel1);//show any of the panel first

    }
  private void initComponents() {

        jPanel1 = new javax.swing.JPanel();
        buttonPanel1 = new javax.swing.JButton();
        buttonPanel2 = new javax.swing.JButton();
        contentPanel = new javax.swing.JPanel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        buttonPanel1.setText("Panel 1");
        buttonPanel1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                buttonPanel1ActionPerformed(evt);
            }
        });

        buttonPanel2.setText("Panel 2");
        buttonPanel2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                buttonPanel2ActionPerformed(evt);
            }
        });
  ....
  }
  private void buttonPanel2ActionPerformed(java.awt.event.ActionEvent evt) {

        contentPanel.removeAll();
        contentPanel.add(panel2);
        contentPanel.repaint();
        contentPanel.revalidate();
    }

    private void buttonPanel1ActionPerformed(java.awt.event.ActionEvent evt) {
        contentPanel.removeAll();
        contentPanel.add(panel1);
        contentPanel.repaint();
        contentPanel.revalidate();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /*
         * Create and display the form
         */
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new myJFrame().setVisible(true);
            }
        });
    }

    private javax.swing.JButton buttonPanel1;
    private javax.swing.JButton buttonPanel2;
    private javax.swing.JPanel contentPanel;
    private javax.swing.JPanel jPanel1;

}

This way is used when you have a tree and show a panel or component on a tree selection. It shows directly that component. On the tree add a value change listener and get the selection item and show appropriate panel.