// Get the viewport of testPane
    JViewport view = testPane.getViewport();
 
    if ( view != null ) {
      // Get the component
      Component c = view.getView();
      // Make sure you have a JTable as view port
      if ( c instanceof JTable ) {
        JTable table = (JTable) c;
        // table is the reference you wanted.
      }
 
    }