title: NullPointerException in a JTextField.getText() inside a actionPerformed event
body: <p>I'm having a <strong>NullPointerException</strong> in a <em>JTextField.getText()</em> inside a <em>actionPerformed</em> event:</p>
  
  <pre><code>import javax.swing.*;
  
  public class myForm extends JInternalFrame
  {
      private JTextField txtName;
      private String name;
  
      public myForm()
      {
          super("My Form", true, true, true, true);
  
          txtName = new JTextField();
  
          JButton button = new JButton("button");
  
          button.addActionListener(new ActionListener()
          {
              public void actionPerformed(ActionEvent e)
              {
                  name = txtName.getText(); // here is the NullPointerException 
              }
          }
      }
  }
  </code></pre>
  
  <p>Here is the stack trace:</p>
  
  <pre><code>Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
      at ContatoFormulario$1.actionPerformed(ContatoFormulario.java:80)
      at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995)
      at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318)
      at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387)
      at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242)
      at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236)
      at java.awt.Component.processMouseEvent(Component.java:6216)
      at javax.swing.JComponent.processMouseEvent(JComponent.java:3265)
      at java.awt.Component.processEvent(Component.java:5981)
      at java.awt.Container.processEvent(Container.java:2041)
      at java.awt.Component.dispatchEventImpl(Component.java:4583)
      at java.awt.Container.dispatchEventImpl(Container.java:2099)
      at java.awt.Component.dispatchEvent(Component.java:4413)
      at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4556)
      at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4220)
      at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4150)
      at java.awt.Container.dispatchEventImpl(Container.java:2085)
      at java.awt.Window.dispatchEventImpl(Window.java:2475)
      at java.awt.Component.dispatchEvent(Component.java:4413)
      at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
      at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
      at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
      at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
      at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
      at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
  </code></pre>
  
  <p>Anyone has a idea? I already try to search over the web and don't find any solution. </p>
  
  <p>This problem occurs with more frequency when we re-instanciate the JTextField like this:</p>
  
  <pre><code>public class myForm extends JInternalFrame
  {
      private JTextField txtName;
  
      public myForm()
      {
          JTextField txtName = new JTextField();        
      }
   }
  </code></pre>
  
  <p>But this is not the case, any idea?</p>