private final static File filefolder=new File("/sdcard/myData");
  private final static File filename=new File("/sdcard/myData/tem.txt");
  public static boolean writeCache(List<Data> list)
  {
    if(!filefolder.exists())
      filefolder.mkdirs();
    try
    {
      JSONArray array=new JSONArray();
      for(int i=0;i<list.size();i++)
      {
        Data data=list.get(i);
        JSONObject ob=new JSONObject();
        ob.put("name", data.getName());
        ob.put("reason", data.getReason());
        array.put(ob);
      }
      FileWriter fw=new FileWriter(filename);
      fw.write(array.toString());
      fw.close();
    }
    catch(Exception e)
    {
      e.printStackTrace();
      return false;
    }
    return true;
  }
  public static List<Data> readCache() throws JSONException,IOException
  {
    if(!filefolder.exists())
      filefolder.mkdir();
    List<Data> list=new ArrayList<Data>();
    if(filename.exists())
    {
      FileInputStream in=new FileInputStream(filename);
      String line=null;
      StringBuffer sb=new StringBuffer("");
      BufferedReader br=new BufferedReader(new InputStreamReader(in));
      while((line=br.readLine())!=null)
        sb.append(line);
      br.close();
      in.close();
      JSONArray array=new JSONArray(sb.toString());
      for(int i=0;i<array.length();i++)
      {
        JSONObject ob=new JSONObject();
        ob=array.getJSONObject(i);
        Data data=new Data();
        data.setName(ob.getString("name"));
        data.setReason(ob.getString("reason"));
        list.add(data);
      }
    }
    return list;
  }