The following is a quickly thrown together method that will return the accepted answer percentage of the user with the given ID.

    public static double getAcceptedAnswerPercentage(StackWrapper sw, int userId)
            throws JSONException, IOException, ParameterNotSetException {
        AnswerQuery query = new AnswerQuery();
        int page = 1;
        int pageSize = 50;
        query.setPage(page).setPageSize(pageSize).setIds(userId);
        int acceptedCount = 0;
        int answerCount = 0;
        while (true) {
            List<Answer> answers = sw.getAnswersByUserId(query);
            for (Answer a : answers) {
                answerCount++;
                if (a.isIsAccepted())
                    acceptedCount++;
            }
            if (answers.size() < pageSize)
                break;
            query.setPage(++page);
        }
        return acceptedCount / (double) answerCount;
    }

Note how the query object is used over and over again, and is updated each time in the iteration.