private void fillList() {
        listView = findViewById(R.id.listView);
        ListAdapter listAdapter = new ListAdapter() {

            @Override
            public void registerDataSetObserver(DataSetObserver observer) {

            }

            @Override
            public void unregisterDataSetObserver(DataSetObserver observer) {

            }

            @Override
            public int getCount() {
                Log.d(TAG, "getCount called. jsonArray.length() = " + jsonArray.length());
                return jsonArray.length();
            }

            @Override
            public Object getItem(int position) {
                Log.d(TAG, "getItem called with " + position);
                try {
                    return jsonArray.get(position);
                } catch (JSONException e) {
                    return null;
                }
            }

            @Override
            public long getItemId(int position) {
                try {
                    return jsonArray.getJSONObject(position).getLong("id");
                } catch (JSONException e) {
                    e.printStackTrace();
                    return -1;
                }
            }

            @Override
            public boolean hasStableIds() {
                return true;
            }

            @Override
            public View getView(int position, View convertView, ViewGroup parent) {
                View view = convertView;
                if (view == null) {
                    view = getLayoutInflater().inflate(R.layout.cell, parent, false);
                }
                TextView left = view.findViewById(R.id.cell);
                left.setText(String.format("zelle %d", position));

                view.setOnClickListener(listener);
                view.setTag(position);
                return view;
            }

            @Override
            public int getItemViewType(int position) {
                return 0;
            }

            @Override
            public int getViewTypeCount() {
                return 1;
            }

            @Override
            public boolean isEmpty() {
                Log.d(TAG, "isEmpty called. jsonArray.length() = " + jsonArray.length());
                return jsonArray == null || jsonArray.length() == 0;
            }

            @Override
            public boolean areAllItemsEnabled() {
                return true;
            }

            @Override
            public boolean isEnabled(int position) {
                return true;
            }
        };
        listView.setAdapter(listAdapter);