Why is the GUI not working, is the code correct? <p>So Im trying to create 3 panels. The first panel has the layout set (e.g. the radio buttons and next button) I`m now adding two new panels which have different background colors. But when I execute the code I get an error of Null point exception. How do I fix that? </p> <p>Here is the code:</p> <pre><code>import java.awt.Color;import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.CardLayout; import javax.swing.*; public class Wizard { private JLabel lblPicture; private JRadioButton btLdap, btKerbegos, btSpnego, btSaml2; private JButton btNext; private JPanel panel; private JPanel panelFirst; private JPanel panelSecond; CardLayout c1 = new CardLayout(); public static void main(String[] args) { new Wizard(); } public Wizard() { JFrame frame = new JFrame("Wizard"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setSize(600,360); frame.setVisible(true); MyPanel(); RadioButtons(); Button(); Image(); groupButton(); panel.setLayout(c1); panelFirst.setBackground(Color.BLUE); panelSecond.setBackground(Color.GREEN); panel.add(panelFirst,"1"); panel.add(panelSecond,"2"); c1.show(panel,"panel"); frame.add(panel); frame.pack(); frame.setVisible(true); } public void MyPanel() { panel = new JPanel(); panel.setLayout(null); } public void RadioButtons() { btLdap = new JRadioButton ("Ldap"); btLdap.setBounds(60,85,100,20); panel.add(btLdap); btKerbegos = new JRadioButton ("Kerbegos"); btKerbegos.setBounds(60,115,100,20); panel.add(btKerbegos); btSpnego =new JRadioButton("Spnego"); btSpnego.setBounds(60,145,100,20); panel.add(btSpnego); btSaml2 = new JRadioButton("Saml2"); btSaml2.setBounds(60,175,100,20); panel.add(btSaml2); } public void Button() { btNext = new JButton ("Next"); btNext.setBounds(400,260,100,20); panel.add(btNext); btNext.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent arg0) { c1.show(panel, "2"); } }); } public void Image() { ImageIcon image = new ImageIcon("image.jpg"); lblPicture = new JLabel(image); lblPicture.setBounds(200,20, 330, 270); panel.add(lblPicture); } private void groupButton() { ButtonGroup bg1 = new ButtonGroup( ); bg1.add(btLdap); bg1.add(btKerbegos); bg1.add(btSpnego); bg1.add(btSaml2); } } </code></pre>