Question

我有一个REST服务，对我的请求进行分页...我需要在我的recyclerview 20上插入itens并在加载之前保留20个itens。

这是我的要求......

VeiculoRequestHelper.veiculosPaginatedRequest(Request.Method.GET, url, null, new Response.Listener<VeiculoPaginated>() {
        @Override
        public void onResponse(VeiculoPaginated response) {
            AnalyticsTracker.getInstance().sendEvent(AnalyticsEnum.Category.MY_VEHICLE, AnalyticsEnum.Action.CLICK, AnalyticsEnum.Label.SUCCESS);

            isLast = response.isLast();

            ArrayList<Veiculo> veiculoArrayList = new ArrayList<>();
            veiculoArrayList.addAll(response.getContent());

            veiculos = veiculoArrayList;

            mAdapter.addItem(veiculos);

            mRecyclerView.setAdapter(mAdapter);

        }
    }, new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
            AnalyticsTracker.getInstance().sendEvent(AnalyticsEnum.Category.MY_VEHICLE, AnalyticsEnum.Action.CLICK, AnalyticsEnum.Label.ERROR);

            Toast.makeText(getActivity(), "Erro ao realizar listagem de veículos.", Toast.LENGTH_LONG).show();
        }
    });

这是我添加新的itens的适配器方法......

    public void addItem(ArrayList<Veiculo> veiculosArray) {
    if (veiculos != null) {
        veiculos.clear();
        veiculos.addAll(veiculosArray);
        notifyItemInserted(veiculos.size() - 1);
    } else {
        veiculos = veiculosArray;
    }
    notifyDataSetChanged();
}

我做错了什么？插入itens但不保留旧的itens ...请帮助！

Answer 1

旧数据将在addItem(ArrayList<Veiculo> veiculosArray)中清除：

if (veiculos != null) {
  veiculos.clear(); // here they will be cleared
  veiculos.addAll(veiculosArray);
  notifyItemInserted(veiculos.size() - 1);
}

删除此行以保留旧项目。

Answer 2

你的onResponse中的

：

 ArrayList<Veiculo> veiculoArrayList = new ArrayList<>();
            veiculoArrayList.addAll(response.getContent());

            veiculos = veiculoArrayList;

            mAdapter.addItem(veiculos);

            mRecyclerView.setAdapter(mAdapter);

看看发生了什么，veiculoArrayList被分配到veiculos表示现在有新的20个项目。将veiculos传递给mAdapter.addItem(veiculos); 并在您的addItem方法

中

veiculos.clear();
veiculos.addAll(veiculosArray);

表示veiculos中的内容将清除，新的列表veiculosArray将被添加到其中（表示新的20个项目）。您不需要清除，添加新项目列表和notifyDatasetChanged()。要专注于最后一项，你只需要设置recyclerView.smoothScrollToPosition（position）; 显然，在将新项目添加到其中之前，位置将是veiculos.size（）。

notifyItemRangeInserted(lastListSize, newList.size());

在RecyclerView上插入新项目

2 个答案: