如何從json獲取列表列表？

Question

我試圖在另一個recyclerview中創建一個recyclerview，並從包含列表列表的API獲取數據。 我成功地在主recyclerview中顯示了數據，但是在子recyclerview中，列表的大小為空。

我試圖制作一個主recyclerview，並在MainAdapter中將其稱為seconed適配器，但在第二個適配器上卻得到了一個空大小，我只需要有人告訴我為什么會出現此錯誤，盡管它已成功加載了數據

API：

{
    "code": 200,
    "Status": "success",
    "data": [
        {
            "id": 3,
            "ar_title": "رجالي",
            "en_title": "Men",
            "img": "1561730519.bb2.jpg",
            "subCategories": [
                {
                    "id": 6,
                    "ar_title": "قمصان",
                    "en_title": "Shirts",
                    "img": "1566590131.celine-druguet-V2WjELpgOEQ-unsplash.jpg"
                },
                {
                    "id": 8,
                    "ar_title": "تيشريت بولو",
                    "en_title": "Polos",
                    "img": "1563560646.bg_1.jpg"
                },
                {
                    "id": 9,
                    "ar_title": "بناطيل",
                    "en_title": "Jeans & Pants",
                    "img": "1563560646.bg_1.jpg"
                },
                {
                    "id": 10,
                    "ar_title": "شورتات",
                    "en_title": "Shorts",
                    "img": null
                },
                {
                    "id": 11,
                    "ar_title": "تيشيرتات",
                    "en_title": "T-shirts",
                    "img": null
                }
            ]
        },
        {
            "id": 4,
            "ar_title": "حريمي",
            "en_title": "Women",
            "img": "1561815572.background.jpg",
            "subCategories": [
                {
                    "id": 12,
                    "ar_title": "فساتين",
                    "en_title": "Dresses",
                    "img": null
                },
                {
                    "id": 13,
                    "ar_title": "تيشيرتات",
                    "en_title": "Tops",
                    "img": "1563560646.bg_1.jpg"
                },
                {
                    "id": 14,
                    "ar_title": "بناطيل",
                    "en_title": "Jeans & Pants",
                    "img": "1563560646.bg_1.jpg"
                },
                {
                    "id": 15,
                    "ar_title": "ليقنز",
                    "en_title": "Leggings",
                    "img": null
                },
                {
                    "id": 16,
                    "ar_title": "تنانير",
                    "en_title": "Skirts",
                    "img": null
                },
                {
                    "id": 17,
                    "ar_title": "ملابس نوم",
                    "en_title": "Sleepwear",
                    "img": null
                }
            ]
        }
    ]
}

InitRetrofit：

AndroidNetworking.get(Constant.BASE_URL+"Categories")
                .setPriority(Priority.MEDIUM)
                .build()
                .getAsObject(AllCategoriesResponse.class, new ParsedRequestListener<AllCategoriesResponse>() {

                    @Override
                    public void onResponse(AllCategoriesResponse response) {
                        /*progress.dismiss();*/

                        if(response.getCode().equals("200"))
                        {
                            if(response.getData().size() > 0)
                                initCategoriesList(response.getData());
                        }
                        else
                        {
                            if(response.getData().size() > 0){
                                initCategoriesList(response.getData());

                            }
                            Toast.makeText(getApplicationContext(),getString(R.string.api_failure_message),Toast.LENGTH_LONG).show();
                        }

                    }

                    @Override
                    public void onError(ANError anError) {
/*
                        progress.dismiss();
*/
                        Toast.makeText(getApplicationContext(),getString(R.string.api_failure_message),Toast.LENGTH_LONG).show();
                    }
                });

ModelResponse：

public class AllCategoriesResponse {

    @SerializedName("code")
    private Long mCode;
    @SerializedName("data")
    private List<Datum> mData;
    @SerializedName("Status")
    private String mStatus;
    //set and get 
    public class Datum {

        @SerializedName("ar_title")
        private String mArTitle;
        @SerializedName("en_title")
        private String mEnTitle;
        @SerializedName("id")
        private Long mId;
        @SerializedName("img")
        private String mImg;
        @SerializedName("subCategories")
        private List<SubCategory> mSubCategories;
        //set and get

        public class SubCategory {

            @SerializedName("ar_title")
            private String mArTitle;
            @SerializedName("en_title")
            private String mEnTitle;
            @SerializedName("id")
            private Long mId;
            @SerializedName("img")
            private String mImg;
            //set and get
       }
   }
}

MainAdapter

public class CategoriesAdapter extends RecyclerView.Adapter<CategoriesAdapter.ViewHolder> {

    Context context;

    private List<AllCategoriesResponse.Datum> list;

    private List<AllCategoriesResponse.Datum.SubCategory> categories;

    public CategoriesAdapter(Context context, List<AllCategoriesResponse.Datum> list) {
        this.context = context;
        this.list = list;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.categories_raw,parent,false);

        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        AllCategoriesResponse.Datum items = list.get(position);

        if(PrefUser.getLanguage(context).equals("ar"))
            holder.textView.setText(items.getArTitle());
        else
            holder.textView.setText(items.getEnTitle());



        SubCategoryAdapter adapter = new SubCategoryAdapter(categories,context);
        GridLayoutManager layoutManager = new GridLayoutManager(context,2);
        holder.recyclerView.setLayoutManager(layoutManager);
        holder.recyclerView.setHasFixedSize(true);
        holder.recyclerView.setAdapter(adapter);

    }

Answer 1

因為您已初始化但未向其中分配任何列表

private List<AllCategoriesResponse.Datum.SubCategory> categories;

解！

AllCategoriesResponse模型類的Datum的make getter方法

public List<SubCategory> getSubCategories(){
  return mSubCategories;
}

使用下面的適配器中的方法

SubCategoryAdapter adapter = new SubCategoryAdapter(items.getSubCategories(),context);

Answer 2

問題是您尚未初始化數據或將數據設置到類別列表。

Private List<AllCategoriesResponse.Datum.SubCategory> categories;
caterories= items.getSubCategories();

Answer 3

選擇要在其上調試應用程序的設備。 在代碼中設置斷點。 在運行時檢查變量並評估表達式。