Parsing a string array from a JSON file into global variable, but when using it the array content is null

I have a JSON file with different Strings I want to create an altert dialog, but my String array is not working

I created a private String category. Into the category String I parse my String values with a for loop, in the method getJobArray. There the LogCat output tells me that the array gets filled with the String values. However, when I use the category String array in the onCreateDialog it tells me that the values are all null. I cannot even print the length to the LogCat

public class MultipleChoiceDialogFragment extends DialogFragment {

    private RequestQueue mRQ;
    private Context mContext;
    private RequestQueue mRequestQ;
    private static String TAG = "xd";
    private String[] category;


    public interface onMultiChoiceListener{
        void onPositiveClicked(String[] list,ArrayList<String> selectedItemList);
        void onNegativeButtonClicked();
    }

    onMultiChoiceListener mListener;

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        mRequestQ = Volley.newRequestQueue(context);
        getJobArray();

        try {
            mListener = (onMultiChoiceListener) context;
        }catch (Exception e){
            throw  new ClassCastException(getActivity() + "onMultiChoice not working error");
        }
    }



    @NonNull
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {

        final ArrayList<String> selectedItemList = new ArrayList<>();



        AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());



        //not working don't understand why... here category is null
        final String[] list = category;

        builder.setTitle("Select one")
                .setMultiChoiceItems(list, null, new DialogInterface.OnMultiChoiceClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i, boolean b) {
                        if(b){
                            selectedItemList.add(list[i]);
                        }else{
                            selectedItemList.remove(list[i]);
                        }
                    }
                })
                .setPositiveButton("OK", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        mListener.onPositiveClicked(list,selectedItemList);

                    }
                })
                .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        mListener.onNegativeButtonClicked();
                    }
                });

        return builder.create();
    }



    private void getJobArray(){
        //todo here I can get array from json array

        String url = "http://api_staging.jab.poweredby.cnddts.at/mobile/metadata/categories?portal=1";
        JsonObjectRequest request = new JsonObjectRequest(com.android.volley.Request.Method.GET, url, null,
                new com.android.volley.Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        try {
                            JSONArray jsonArray = response.getJSONArray("categories");

                            category = new String[jsonArray.length()];

                            Log.d(TAG, "onResponse: is getting array ready right now");
                            Log.d(TAG, "onResponse: jsonArray length" + jsonArray.length());
                            for(int i = 0; i < jsonArray.length(); i++){
                                JSONObject categories = jsonArray.getJSONObject(i);

                                category[i] = categories.getString("name");

                                Log.d(TAG, "onResponse: array input " + category[i]);

                            }


                        } catch (JSONException e) {
                            e.printStackTrace();
                            Log.d(TAG, "onResponse: catch caught...");
                        }

                    }
                }, new com.android.volley.Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                error.printStackTrace();
            }
        });

        mRequestQ.add(request);
    }
}