Having a Null pointer exception while coding my first GUI and I can't figure out where it's going wrong : <pre><code>import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;


public class JFrameTest  {

    private MyListener listener = new MyListener();
    private JButton clear = null;
   private JButton addOne = null;
   private static JFrame frame = null;
   private JTextField text1 = null;
   private JTextField text2 = null;
   private JTextField text3 = null;
   private JTextField text4 = null;
   private JTextField text5 = null;
   private JTextField text6 = null;

public static void main(String[] args) {

    javax.swing.SwingUtilities.invokeLater(new Runnable() {
        public void run() {
            createAndShowGUI();
        }
    });
}
private static void createAndShowGUI() {
    //Create and set up the window.
    frame = new JFrame("Button &amp; Listener Demo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    frame.add(new JFrameTest().createGUI());

    //Display the window.
    frame.setSize(800, 500);
    frame.setVisible(true);
}

public JTabbedPane createGUI(){
    JTabbedPane tabbedPane = new JTabbedPane();
    JPanel one = new JPanel();
    one.setLayout(new BorderLayout());
    JPanel test = new JPanel();
    JPanel test2 = new JPanel();


   JLabel label1 = new JLabel ("Pound");
   JLabel label2 = new JLabel("Ounce :" );
   JLabel label3 = new JLabel("Ton :");
   JLabel label4 = new JLabel("Tonne :");
   JLabel label5 = new JLabel("Kilogram :");
   JLabel label6 = new JLabel("Gram :");
   text1 = new JTextField(5);
   text2 = new JTextField(5);
   text3 = new JTextField(5);
   text4 = new JTextField(5);
   text5 = new JTextField(5);
   text6 = new JTextField(5);
   JButton button = new JButton();

    clear = new JButton("Clear");
    clear.addActionListener(listener);

    text1.setText("0");
    text2.setText("0");
    text3.setText("0");
    text4.setText("0");
    text5.setText("0");
    text6.setText("0");
    test.add(label1);
    test.add(text1);
    test.add(label2);
    test.add(text2);
    test.add(label3);
    test.add(text3);
    test2.add(label4);
    test2.add(text4);
    test2.add(label5);
    test2.add(text5);
    test2.add(label6);
    test2.add(text6);
    one.add(test, BorderLayout.NORTH);
    one.add(test2, BorderLayout.CENTER);
    one.add(clear, BorderLayout.SOUTH);

    tabbedPane.addTab("Tab 1", one);
    JPanel two = new JPanel();
    tabbedPane.addTab("Tab 2", two);




    return tabbedPane;
    }




public class MyListener implements ActionListener{

    @Override
    public void actionPerformed(ActionEvent e) {
        JButton source = (JButton)e.getSource();
                    String sourceName = source.getName();

                    if(sourceName.equals("Clear"))
                    {
                        System.out.println("yeet");
                        text1.setText("00");                           
                        text2.setText("00");
                      text3.setText("00");
                       text4.setText("00");
                       text5.setText("00");
                      text6.setText("00");
                    }
                    else
                    {
                        System.out.println("nah");
                    }


    }

}


}
</code></pre>

<blockquote>
  <p>And my error code is:Exception in thread "AWT-EventQueue-0"
  java.lang.NullPointerException
        at jframetest.JFrameTest$MyListener.actionPerformed(JFrameTest.java:123)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
        at java.awt.Component.processMouseEvent(Component.java:6533)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
        at java.awt.Component.processEvent(Component.java:6298)
        at java.awt.Container.processEvent(Container.java:2236)
        at java.awt.Component.dispatchEventImpl(Component.java:4889)
        at java.awt.Container.dispatchEventImpl(Container.java:2294)
        at java.awt.Component.dispatchEvent(Component.java:4711)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
        at java.awt.Container.dispatchEventImpl(Container.java:2280)
        at java.awt.Window.dispatchEventImpl(Window.java:2746)
        at java.awt.Component.dispatchEvent(Component.java:4711)
        at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
        at java.awt.EventQueue.access$500(EventQueue.java:97)
        at java.awt.EventQueue$3.run(EventQueue.java:709)
        at java.awt.EventQueue$3.run(EventQueue.java:703)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
        at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
        at java.awt.EventQueue$4.run(EventQueue.java:731)
        at java.awt.EventQueue$4.run(EventQueue.java:729)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)</p>
</blockquote>
