title: Swing error ClassCastException
body: <p>This is the Code I typed</p>
  
  <pre><code>// loading all distict age on to list bix from student table
   private void b1ActionPerformed(java.awt.event.ActionEvent evt) {                                   
  DefaultTableModel tb = (DefaultTableModel)tb1.getModel();
  tb.setRowCount(0);
  String sql = "select * from student";
  try
  {
  Class.forName("java.sql.Driver");
  Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/info","root","");  
  Statement s = con.createStatement();
  ResultSet rs = s.executeQuery(sql);
  while(rs.next())
  {
      int s_rno = rs.getInt(1);
      String s_name = rs.getString(2);
      int s_age = rs.getInt(3);
      double s_marks = rs.getDouble(4);
      tb.addRow(new Object[]{s_rno, s_name, s_age, s_marks});
      tb1.setModel(tb);
  }
  rs.close();
  s.close();
  con.close();
  }
  catch(Exception e)
  {
      JOptionPane.showMessageDialog(this, e.getMessage());
  }        
  }
  </code></pre>
  
  <p>And when I run the program, the GUI appears, but on pressing the button, nothing happens, and there is the following error on my output window</p>
  
  <blockquote>
    <p>Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException:
    JDBC2$2 cannot be cast to javax.swing.DefaultListModel    at
    JDBC2.b1ActionPerformed(JDBC2.java:74)    at
    JDBC2.access$000(JDBC2.java:9)    at
    JDBC2$1.actionPerformed(JDBC2.java:36)    at
    javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
      at
    javax.swing.AbstractButton$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:6535)    at
    javax.swing.JComponent.processMouseEvent(JComponent.java:3324)    at
    java.awt.Component.processEvent(Component.java:6300)  at
    java.awt.Container.processEvent(Container.java:2236)  at
    java.awt.Component.dispatchEventImpl(Component.java:4891)     at
    java.awt.Container.dispatchEventImpl(Container.java:2294)     at
    java.awt.Component.dispatchEvent(Component.java:4713)     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:2750)   at
    java.awt.Component.dispatchEvent(Component.java:4713)     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:76)
      at
    java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
      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:76)
      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>
  
  <p>I need more help , how i can comprehend the error.</p>