Repeating numbers random Android studio java random array problem

i have a problen with random in arrays. It is like a quiz and i have arrays with questions,choises and answers. When i start my quiz , qustions are repeating
Know about shuffle but do not know how to use it
i have a method:

 private void updateQuestion(int num){
    question.setText(mQuestionAvtor.getQuestion(num));
    answer1.setText(mQuestionAvtor.getChoice1(num));
    answer2.setText(mQuestionAvtor.getChoice2(num));
    answer3.setText(mQuestionAvtor.getChoice3(num));
    answer4.setText(mQuestionAvtor.getChoice4(num));
    mAnswear= mQuestionAvtor.getCorrectAnswear(num);
}

It updates my questions from another Class with arrays by a num.
This num i did by random :

updateQuestion(r.nextInt(mQuestionslength));

Example of updating questions

  answer1 = (Button) findViewById(R.id.answear1);
    answer2 = (Button) findViewById(R.id.answear2);
    answer3 = (Button) findViewById(R.id.answear3);
    answer4 = (Button) findViewById(R.id.answear4);
    question = (TextView) findViewById(R.id.question);


    n = r.nextInt(mQuestionslength);
    while (n == n_before)
        n = r.nextInt(mQuestionslength);
    n_before = n;
    updateQuestion(n);
    answer1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            if(answer1.getText()==mAnswear){
                mScore++;
                mScorecurrent.setText("Рахунок: "+mScore);
            }

            n = r.nextInt(mQuestionslength);
            while (n == n_before) n = r.nextInt(mQuestionslength);
            n_before = n;
            updateQuestion(n);
        }
    });

I need to do it in a such way , that r will not repeat. How can I do it?
Thanks in advance!

First pre-create a random list of the questions you want to show.

Random rand = new Random();
List<Integer> rlist = new ArrayList<>();
while (rlist.size() != 4) {
int r = rand.nextInt(4) + 1;
if (!rlist.contains(r))
       rlist.add(r);
}
//output of rlist is like: [2, 3, 4, 1] or [1, 3, 4, 2]

Then count an index up after clicking the button and generate get a question with the current number.

int index = 0;
updateQuestion(rlist.get(index));
    answer1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if (i < 4) {
            if(answer1.getText()==mAnswear){
                mScore++;
                mScorecurrent.setText("Рахунок: "+mScore);
            }

            
            updateQuestion(rlist.get(index));
            index++;
            } else {
                //To do after the last question
            }
        }
    });

You can create an ArrayList of integers to store questions number already shown to the user and next time before setting question you can check if the questions number was already in ArrayList or not, If not ask the question to user.

    ArrayList<int> num  = ArrayList<int>()
    int temp = r.nextInt(mQuestionslength)
    while(num.contains(temp))
    {
        temp = r.nextInt(mQuestionslength)
    }
    num.add(temp);
    updateQuestion(temp);

There's a famous algorithm called the Fisher-Yates Shuffle. Here is an implementation in Java. You can use it to shuffle the array of answers.