how to generate random paper by using random function

I want to generate the random question paper. What I have tried till is this

public Set<Question> generateQuestionPaper(List<Question> list,
            List<Criteria> template) {
        // TODO Auto-generated method stub

        Set<Question> s=new HashSet<Question>();
        Random rand = new Random();
        for(int i=0;i<template.size();i++)
        {
            int cnt=0;
            for(int k=i;k<QuestionList.size();k++)
            {

                if(template.get(i).getComplexity()==QuestionList.get(k).getComplexity() && template.get(i).getCategory()==QuestionList.get(k).getCategory())
                {
                    if(cnt<template.get(i).getNoOfQuestion())
                    {
                        s.add(QuestionList.get(k));
                        cnt++;



                    }
                    else
                        break;
                }
            }

        }

        return s;


    }

The QuestionList holds the questions wheres as template list holds the template like

 template.add(new Criteria(Category.GK,Complexity.Simple,2));
        template.add(new Criteria(Category.GK,Complexity.Medium,1));
        template.add(new Criteria(Category.GK,Complexity.Complex,1));
        template.add(new Criteria(Category.Science,Complexity.Complex,1));
        template.add(new Criteria(Category.History,Complexity.Medium,2));
        template.add(new Criteria(Category.History,Complexity.Simple,2));
        template.add(new Criteria(Category.Geography,Complexity.Medium,1));

what I am doing is just checking whether the category and complexity given in the template list is also there in questionList. It provides perfect output that is 2 GK questions which are simple, 1 GK question which is complex and so on as given in the template. But it is not generating random paper.

I know to generate random paper we have to use random function but i am not getting how to use it.

Database holds the values like queno,question,option1,option2,option3,correctans,complexity,category etc.

Please someone tell me how can I use random function to generate unique paper each time.

Thank you