我写的Java学生成绩管理系统源代码

我写的Java学生成绩管理系统源代码(18)                                 new FileWriter("data.txt")));
            Iterator it = dal.iterator();
            long temp = 0;
            String tempStr = "";
            while (it.hasNext())
            {
                temp = Integer.valueOf((String)it.next()).longValue();
                tempStr = dm.get(temp);
                out.println(tempStr);
            }
            out.close();
        }catch(IOException e){}
    }
    public void rewrite()
    throws IOException,NumberNotFoundException
    {
        try{
            System.out.print("请输入你要修改的学生学号:");
            BufferedReader in =
                new BufferedReader (
                        new InputStreamReader(System.in));
            String inputLine = in.readLine();