android - JSON 解析的问题

Question

我正在开发一个简单的新闻应用程序。 我需要以 JSON 格式从远程服务器获取数据，然后将其放在 View 中。我使用 TabLayout 和 recyclerView 来显示数据类别，并使用 Volley 进行查询，这里没有 API。

TabLayout 是根据 JSON 中的数据自动设置的，我在其中提取选项卡标题，每个选项卡的内容都显示在 recyclerView 上(文章标题、图像、内容、链接...)并在 fragment 内呈现​​

我花了几个小时试图调试它但没有成功。但无论我做什么，都没有显示任何数据。不确定我做错了什么。

我知道这不是要求此类事情的正确位置，但我有点绝望，需要一些有经验的开发人员来查看我的问题。

工作原理:

Activity 启动 BaseArticleFragment，它调用加载内容类别并将数据绑定(bind)到 View 的方法:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    this.fm = getSupportFragmentManager();
    this.baseArticleFragment = new BaseArticleFragment();
    FragmentTransaction ft = this.fm.beginTransaction();
    ft.add(R.id.fragment_container, this.baseArticleFragment, TAB_LAYOUT_FRAGMENT_TAG); 
    ft.commit();
}

启动时，baseArticleFragment 在其 onActivityCreated() 方法中调用 loadCategories() 方法:

@Override
public void onActivityCreated(Bundle savedInstanceState){
    super.onActivityCreated(savedInstanceState);
    loadCategories();
}

这里是 loadCategories() 方法:

private void loadCategories(){
    String url = "http://somesite.com/categories"; //link to grab the json data
    ApplicationController.getInstance().addToRequestQueue(
            new JsonObjectRequest(0, url, null, new Listener<JSONObject>() { //0 is the Volley code for GET method
                @Override
                public void onResponse(JSONObject jsonObject) {
                    BaseArticleFragment.categories = JSONParser.parseCategories(jsonObject);
                    BaseArticleFragment.this.mViewPager.setAdapter(
                            new RecyclerViewFragmentPagerAdapter(BaseArticleFragment.this.getChildFragmentManager(),
                                    BaseArticleFragment.categories));
                    BaseArticleFragment.this.mTabLayout.setupWithViewPager(BaseArticleFragment.this.mViewPager);
                }
            }, new Response.ErrorListener() {
                    @Override
                   public void onErrorResponse(VolleyError vError){
                        Log.d("BaseArticleFragment", "---Volley Error---");
                        Snackbar.make(BaseArticleFragment.this.mTabLayout, R.string.error_load_categories, Snackbar.LENGTH_SHORT)
                                .setAction(R.string.action_retry, new View.OnClickListener() {
                                    @Override
                                    public void onClick(View v) {
                                        BaseArticleFragment.this.loadCategories();
                                    }
                                }).show();
                    }
                }));
}

我想问题可能出在查询上，但不确定，因为我认为我的逻辑很好

编辑:

这是我需要获取的 JSON 数据:

[
  {
    "name": "Topic 1",
    "tid": "2",
  },
  {
    "name": "Topic 2",
    "tid": "3",
  },
  {
    "name": "Topic 3",
    "tid": "4",
  },
  {
    "name": "Topic 4",
    "tid": "5",
  },
  {
    "name": "Topic 5",
    "tid": "6",
  },
  {
    "name": "Topic 6",
    "tid": "1415",
  },
  {
    "name": "Topic 7",
    "tid": "1414",
  },
  {
    "name": "Topic 8",
    "tid": "1298",
  },
  {
    "name": "Topic 9",
    "tid": "1301",
  },
  {
    "name": "Topic 10",
    "tid": "1299",
  },
  {
    "name": "Topic 11",
    "tid": "1302",
  },
  {
    "name": "Topic 12",
    "tid": "1300",

  },
  {
    "name": "Topic 13",
    "tid": "1297",
  }
]

编辑 2: 我忘记将 parseCategories() 的代码粘贴到我的 JSONPARser 类中

 public static ArrayList<Category> parseCategories(JSONObject jsonObject) {
    ArrayList<Category> categoryArrayList = new ArrayList<>();
    try {
        JSONArray categories = jsonObject.getJSONArray("categories");
        Category all = new Category();
        all.setTid("0");
        all.setName(ApplicationController.getInstance().getString(R.string.tab_all));
        categoryArrayList.add(all);
        for (int i = 0; i < categories.length(); i++) {
            JSONObject catObject = categories.getJSONObject(i);
            Category category = new Category();
            category.setTid(catObject.getString("tid"));
            category.setName(catObject.getString("name"));              
            categoryArrayList.add(category);
        }
        return categoryArrayList;

    } catch (JSONException e) {
        e.printStackTrace();
        return null;
    }

}

Answer 1

试试这个@esQmo_，

StringRequest stringRequest = new StringRequest(url , new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {

                try {
                    JSONArray jsonArray = new JSONArray(response);

                    ArrayList<Hashmap<String,String>> arraylist = new 
                                                            ArrayList<>();
                    for (int i = 0; i < jsonArray.length(); i++) {

                    HashMap<String, String> hashMap = new HashMap<>();
               String name = 
                      jsonArray.getJSONObject(i).getString("name");
                     String tid = 
                     jsonArray.getJSONObject(i).getString("tid");

                     hashMap.put("name", name);
                     hashMap.put("tid ", tid ); 
                     arraylist.add(hashMap);
                     Log.e("response",name + "\n" + tid);
                   }

              attachAdapter(arraylist);

                } catch (JSONException e) {
                    e.printStackTrace();
                }


            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });

        RequestQueue queue = Volley.newRequestQueue(this);
        queue.add(stringRequest);

     //setting adapter data to the RecyclerView
    private void attachAdapter(ArrayList<HashMap<String, String>> 
    arrayList) {

    ExampleAdapter adapter = new ExampleAdapter(arrayList,this);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setAdapter(adapter);
    adapter.notifyDataSetChanged();
 }
}

这是适配器类

public class ExampleAdpater extends RecyclerView.Adapter<ExampleAdpater.ExampleViewHolder>{

public ArrayList<HashMap<String,String>> arraylist;

public Context context;

public ExampleAdpater(ArrayList<HashMap<String, String>> arraylist, Context context) {
    this.arraylist= arraylist;
    this.context = context;
}

@NonNull
@Override
public ExampleViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.textLayout,viewGroup,false);
    return new ExampleViewHolder(view);
}

@Override
public void onBindViewHolder(@NonNull ExampleViewHolder viewHolder, int i) {

    HashMap<String,String> hashMap = arraylist.get(i);
    viewHolder.name.setText(hashMap.get("name"));
    viewHolder.tid.setText(hashMap.get("tid"));

}

@Override
public int getItemCount() {
    return arraylist.size();
}

public class ExampleViewHolder extends RecyclerView.ViewHolder{

    TextView name,tid;

    public ExampleViewHolder(@NonNull View itemView) {
        super(itemView);

        name = itemView.findViewById(R.id.name);
        tid = itemView.findViewById(R.id.tid);

        name.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(v.getContext(), ""+name.getText().toString(), 
          Toast.LENGTH_SHORT).show();
            }
        });

        }
   }
  }

文本布局.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/name"
    />

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/tid"
    />


</LinearLayout>