向已获取的list中插入值

public List getWfList(String id){
NetSpGeneralbillInfo vo = this.findOne(id);
String sql = " select flowId, pdkey pd from net_SP_billAndWf  where billId='"+vo.getBillId()+"' ";
List list = this.getListBySql(sql);

NetWorkInstanceUtil instanceutil = new NetWorkInstanceUtil();
Map pds = instanceutil.getPdDescriptions();
for(int i=0;i<list.size();i++){
Object[] obj = (Object[])list.get(i);
obj[1]= pds.get(obj[0].toString());// pd值发生改变
}

return list;
}