cvt.start();
workingThread.start();
   private void doExport() {      if (!pagesValid())         return;      Thread cvt = null;      if (cvtType.getSelectedIndex() == 0)         cvt = new Thread(new Runnable () {            public void run() {               cvtToPDF();            }         });      else         cvt = new Thread(new Runnable () {            public void run() {               cvtToText();            }         });      cvt.start();   }