拷贝文章时对自然段进行排序（案例）

try (

            BufferedReader br = new BufferedReader( new FileReader("F:\JavaProject\Project\src\app.txt"));
            BufferedWriter bw = new BufferedWriter( new FileWriter("F:\JavaProject\Project\src\lid") );

            ){
        List<String> list = new ArrayList<>();
        String sr;
        while ((sr = br.readLine()) !=null){
            list.add(sr);
        }
        List<String> str = new ArrayList<>();
      Collections.addAll(str,"一","二","三","四","五","六");
     Collections.sort(list, new Comparator<String>() {
         @Override
         public int compare(String o1, String o2) {
             return str.indexOf(o1.substring(0,o1.indexOf("."))) - str.indexOf(o2.substring(0,o2.indexOf(".")));
         }
     });
        for (String s : list) {
            bw.write(s);
            bw.newLine();
        }

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