Get only selected checkboxes from recyclerview in android

// this is my QuestionFragment_Activity class where i will get questions from server

public class QuestionFragment_Activity extends Fragment implements FragmentObserver {

private static final String CATEGORY_ID = "question_fragment_category_id";
private static final String QUESTIONS = "question_fragment_questions";

private RecyclerView recyclerView;
private QuestionAdapter adapter;
private JSONArray questions = null;
private int categoryId;
private Button button;


public QuestionFragment_Activity() { }

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (savedInstanceState != null) {
        try {
            questions = new JSONArray(savedInstanceState.getSerializable(QUESTIONS));
        } catch (JSONException je) { }
    }
    if (questions == null) {
        categoryId = (int) getArguments().getSerializable(CATEGORY_ID);
        try {
         // this is request to the server




            questions = Resource.getInstance().getQuestions(categoryId);
             JSONObject request = new JSONObject();
             request.put("_module", "Category");
             JSONObject payload = new JSONObject();
             payload.put("_task", "getquestions");
             payload.put("_uhid",2);
             payload.put("_pid", categoryId);
             request.put("_payload", payload);
             new Service(this).sendRequest(request);

        } catch (JSONException je) {

        }
        //questions  = Resource.getInstance().getQuestions(categoryId);
    }
}

@Override
public void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    if (questions != null)
        outState.putString(QUESTIONS, questions.toString());
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    final View view = inflater.inflate(R.layout.fragment_question, container, false);
    button = (Button) view.findViewById(R.id.button);
    recyclerView = (RecyclerView) view.findViewById(R.id.question_recycler);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Toast.makeText(getContext(),"in side click",Toast.LENGTH_SHORT).show();
        }
    });
    updateUI();
    return view;
}

@Override
public void onResume() {
    super.onResume();
    updateUI();
}

@Override
public void onAttach(Activity activity) {
    super.onAttach(activity);
}

@Override
public void onDestroy() {
    super.onDestroy();
}

@Override
public void onSuccess(JSONObject response) {
    try {
        questions = response.getJSONArray("_questions");
        updateUI();
    } catch (JSONException je) { }
}

@Override
public Context getContext() {
    return getActivity();
}

@Override
public void onFailure(String message) {

}

public static QuestionFragment_Activity newInstance(int categoryId) {
    Bundle args = new Bundle();
    args.putSerializable(CATEGORY_ID, categoryId);
    QuestionFragment_Activity questionFragment = new QuestionFragment_Activity();
    questionFragment.setArguments(args);
    return questionFragment;
}

public void updateUI() {
    if(adapter == null) {
        if(questions != null) {
            adapter = new QuestionAdapter(questions);
            recyclerView.setAdapter(adapter);
            recyclerView.setItemViewCacheSize(questions.length());
        }
    }
}

// this is my QuestionHolder class

private class QuestionHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    private JSONObject question;
    private CheckBox checkBox;
    private TextView question_txt;
    public QuestionHolder(final LayoutInflater inflater, final ViewGroup parent) {
        super(inflater.inflate(R.layout.question_item, parent, false));
        checkBox  = (CheckBox) itemView.findViewById(R.id.question_checkbox);
        question_txt = (TextView) itemView.findViewById(R.id.question);
        itemView.setOnClickListener(this);
    }

    public void bind(JSONObject question) {
        this.question = question;
        try {
            question_txt.setText(question.getString("_question"));
        } catch (JSONException je) { }
    }
    @Override
    public void onClick(View v) {

    }
}

// this my QuestionAdapter Class

private class QuestionAdapter extends RecyclerView.Adapter<QuestionHolder> {

    SparseBooleanArray sparseBooleanArray = new SparseBooleanArray();
    private JSONArray questions;

    public QuestionAdapter(JSONArray questions) {
        this.questions = questions;
    }

    @Override
    public QuestionHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        return new QuestionHolder(LayoutInflater.from(getActivity()), parent);
    }

// this is my onBindViewHolder where I am using one SparseBooleanArray for selecting

    @Override
    public void onBindViewHolder(final QuestionHolder holder, final int position) {
        try {
            final JSONObject question = questions.getJSONObject(position);
            holder.checkBox.setOnCheckedChangeListener(null);

            holder.checkBox.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    try {
                        sparseBooleanArray.put(position,true);

                        Toast.makeText(getActivity(),""+question.get("_id"), Toast.LENGTH_SHORT).show();
                    } catch (JSONException e) { }
                 /*   int pos= holder.getAdapterPosition();
                    final boolean newvalue = !holder.checkBox.isChecked();
                    sparseBooleanArray.put(pos,newvalue);
                    getselectedItemspositions();
                   // sparseBooleanArray.put(pos,true);
                    Toast.makeText(getContext(),"Item favoued"+getselectedItemspositions(),Toast.LENGTH_LONG).show();*/
                    //Toast.makeText(getContext(),"Item favoued"+v,Toast.LENGTH_LONG).show();
                   // sparseBooleanArray.put(position,true);

                }
            });
            holder.bind(question);

        } catch (JSONException je) { }

    }
    @Override
    public int getItemCount() {
        return questions.length();
    }
}

}