这种方法的逻辑？

Question

我正在创建一个生成问题的java应用程序，下面显示的方法用于生成问题。我已经使用堆栈来按顺序排列这些问题。 我的问题是它不断产生多个相同的问题，这个方法应该阻止。

   public ArrayList<String> generateQuestions(String transcript, String className, int classYear, String classGroup) {
    ArrayList<String> results = new ArrayList<String>();
    ArrayList<String> tags = new ArrayList<String>();

    //get tags from the database
    Statement stmt = null;
    try {
        stmt = handler.getConnection().createStatement();
    } catch (SQLException e) {
        e.printStackTrace();
    }
    if(stmt != null){
        try {
            String result = "";
            ResultSet rs = stmt.executeQuery("SELECT tags.TagName FROM class, tags, questtag, questions, questclass WHERE questtag.QuestionID = questions.QuestionID AND tags.TagID = questtag.TagID AND questions.QuestionID = questclass.QuestionID AND questclass.ClassID = class.ClassID AND class.ClassName ='"+className+"' AND class.ClassYear="+classYear+" AND class.ClassGroup ='"+classGroup+"' GROUP BY tags.TagID");

            while (rs.next()) {
                result = rs.getString(1);
                tags.add(result);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    Stack<Question> stack = new Stack<Question>();
    for (String word : transcript.split("\\s+")) {
        if(  ! word.equalsIgnoreCase("the") || ! word.equalsIgnoreCase("I")) {
            for(String tag : tags) {
                if(word.equalsIgnoreCase(tag)) {
                    try {
                        stmt = handler.getConnection().createStatement();
                    } catch (SQLException e) {
                        e.printStackTrace();
                    }
                    if(stmt != null){
                        try {
                            String result = "";
                            ResultSet rs = stmt.executeQuery("SELECT questions.Question FROM class, tags, questtag, questions, questclass WHERE questtag.QuestionID = questions.QuestionID AND tags.TagID = questtag.TagID AND questions.QuestionID = questclass.QuestionID AND questclass.ClassID = class.ClassID AND class.ClassName ='"+className+"' AND class.ClassYear="+classYear+" AND class.ClassGroup ='"+classGroup+"' AND tags.TagName = '"+tag+"'");
                            while (rs.next()) {
                                result = rs.getString(1);
                                Stack<Question> searchStack = new Stack<Question>();
                                boolean multiple = false;
                                if(stack.isEmpty()) { //1st question we've come to
                                    Question question = new Question(result);
                                    stack.push(question);
                                } else {
                                    while(multiple == false && !stack.isEmpty()) {
                                        //search through the stack
                                        searchStack.push(stack.pop());
                                        //if question is not already in the stack
                                        if(((Question)searchStack.peek()).getQuestion().equalsIgnoreCase(result)) {
                                            //then it is multiple
                                            //add one to its noOfTimes
                                            ((Question)searchStack.peek()).addToNoOfTimes();
                                            //order this above others with lower score
                                            if(!stack.isEmpty()) {
                                                if(((Question)stack.peek()).getNoOfTimes() < ((Question)searchStack.peek()).getNoOfTimes()) {
                                                    Question thisQuestion = searchStack.pop();
                                                    while(((Question)stack.peek()).getNoOfTimes() < thisQuestion.getNoOfTimes() && !stack.isEmpty()) {
                                                        searchStack.push(stack.pop());
                                                }
                                                stack.push(thisQuestion);
                                            } else {
                                                stack.push(searchStack.pop());
                                            }
                                        }
                                        multiple = true;
                                    }

                                }

                                while(!searchStack.empty())
                                    stack.push(searchStack.pop());
                                if(multiple == false) {
                                    Question question = new Question(result);
                                    stack.push(question);
                                } 
                                }
                            }
                        } catch (SQLException e) {
                            e.printStackTrace();
                        }
                        Stack<Question> reorderStack = new Stack<Question>();
                        while(!stack.empty()) {
                            reorderStack.push(stack.pop());
                        }
                        while(!reorderStack.empty()) {
                            Question thisQuestion = reorderStack.pop();
                            results.add(thisQuestion.getQuestion());
                            stack.push(thisQuestion);
                        }
                    }


                }
            }
        }
    }

    return results;
}