OutputStreamWriter輸出txt分行顯示

OutputStreamWriter op = new OutputStreamWriter(new FileOutputStream("c:\\users\\cc\\desktop\\123.txt"), "utf-8");
op.append("猜猜會不會顯示"+"\n");//這邊"\n"不起作用
op.append("\r\n");//換行
op.append("換行成功");
op.flush();
op.close();