private void Button_GOMouseClicked(java.awt.event.MouseEvent evt) {
       String c=TextArea_IO.getText();
        if(c=="a")
       {
       	try
        {

		if ((new File("c:\\Users\\Federico\\Desktop\\rinuncia_studi.pdf")).exists())
                {

			Process p = Runtime
			   .getRuntime()
			   .exec("rundll32 url.dll,FileProtocolHandler c:\\Users\\Federico\\Desktop\\rinuncia_studi.pdf");
                           TextArea_IO.setText("PORCODDIO");

			p.waitFor();

		}
                else
                {

			TextArea_IO.setText("File does not exist");

		}

		TextArea_IO.setText("There you go");

        }
        catch (Exception ex)
        {
		ex.printStackTrace();
	 }
       }
    }