if ( f != null ) {
if ( f != null )
    public void destroy() {        debug("destroy called");        try {            SFrame f = getFrame();            if ( f != null ) {                f.getContentPane().removeAll();                f.getOptionPaneContainer().removeAll();            }        }        catch ( Exception e ) {            e.printStackTrace();        }        finally {            Runtime rt = Runtime.getRuntime();            if ( DEBUG ) debug("free mem before gc: " + rt.freeMemory());            rt.gc();            if ( DEBUG ) debug("free mem after gc: " + rt.freeMemory());        }    }