private void updateTask(HashMap<Keyword, String> parameters) {
        String start = "";
        String end = "";
        String newContent = "";
        String isCompleted = "";
        String key = parameters.get(Keyword.CONTENT);
        if (parameters.containsKey(Keyword.NEWCONTENT)) {
            newContent = parameters.get(Keyword.NEWCONTENT);
        }
        if (parameters.containsKey(Keyword.COMPLETED)) {
            isCompleted = parameters.get(Keyword.COMPLETED);
        }
        if (parameters.containsKey(Keyword.START)) {
            start = parameters.get(Keyword.START);
        }
        if (parameters.containsKey(Keyword.END)) {
            end = parameters.get(Keyword.END);
        }
        ArrayList<Task> queryResult = dataHandler.updateTask(key, newContent, 
                                                             start, end, 
                                                             isCompleted);
        
        String firstOutputLine = "";

        if (!dataHandler.getNearMatchString().equals("")) {
            firstOutputLine += ANNOUNCEMENT_SUGGESTION 
                  + dataHandler.getNearMatchString() + "?\n";
        }
        
        if (queryResult.isEmpty()) {
            firstOutputLine += ANNOUNCEMENT_NOT_FOUND;
            result.add(firstOutputLine);
            return;
        }
        firstOutputLine += ANNOUNCEMENT_UPDATE;
        result.add(firstOutputLine);

        for (Task i : queryResult) {
            result.add(i.getDisplayedString());
        }
    }