Swing Dialog Error

I'm adding the below event to a menu item, to trigger a dialog box.

------------
private void jMenuItem2ActionPerformed(java.awt.event.ActionEvent evt) {
   JOptionPane.showMessageDialog(null, "test dialog");

}
-------------

However, I'm getting the below errors!
------------------
forte4j/Development/db2.java [244:1] Undefined variable, class, or package name: JOptionPane
   JOptionPane.showMessageDialog(null, "test dialog");
   ^
forte4j/Development/db2.java [244:1] Invalid expression statement.
   JOptionPane.showMessageDialog(null, "test dialog");
   ^

---------------------

I'm adding other components to the JFrame like so :
getContentPane().add(searchHeader);


How do I get the dialog to work?