这个Java程序怎么写，能提供具体思路否

 public static void main(String[] args) {
        BufferedWriter bw = null;
        BufferedReader br = null;
        try {
            br = new BufferedReader(new InputStreamReader(new FileInputStream("D:\\score.txt")) {
            });
            List<String> achievList = new ArrayList<>();
            String str = null;
            while ((str = br.readLine()) != null) {
                achievList.add(str);
            }

            List<String> achievList2 = new ArrayList<>();
            for (int i = 0; i < achievList.size(); i++) {
                String achiev = achievList.get(i);
                double num=getotalScore(achiev);
                achievList2.add(achiev+"总分："+num);
            }

            bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("D:\\scoreAnalysis.txt")));
            for (String i : achievList2) {
                bw.write(i);
                bw.newLine();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (bw != null) {
                    bw.close();
                }
                if (br != null) {
                    br.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

读取文件内容
计算学生成绩
追加学生总成绩
写入文件