如何在 Android Recyclerview 中显示 JSON 数组中包含的 JSON 对象
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【中文标题】如何在 Android Recyclerview 中显示 JSON 数组中包含的 JSON 对象【英文标题】：How to show JSON objects included in JSON Array in Android Recyclerview 【发布时间】：2021-08-28 08:33:14 【问题描述】：我有以下 JSON 数据，即一个数组中有 10 个对象。我在 recyclerview 中获取对象，没有任何错误。
现在我需要做两件事：
-
我想在用户滚动 recyclerview 时显示下一页数据，即（接下来的 10 条记录，依此类推）。
我想在recyclerview 中显示每个对象的total_quotes。我在显示总引号时遇到“LeadsMeta.getTotalQuotes()' on a null object reference”这个错误。
我已经在 Adapter 的 onBind 中注释了该行。
请帮我解决这两个问题。非常感谢。
JSON 数据
"meta":
"code":200,
"message":"success",
"total_pages":247,
"current_page":1,
"total_items":2469,
"total_quotes":5
,
"data":[
"id":"4968",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Pune",
"name":"Shashikant ",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 21:53:38"
,
"id":"4963",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Bangalore",
"name":"Amani",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 20:46:03"
,
"id":"4962",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Delhi",
"name":"Mechanical Engineer",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 20:23:00"
,
"id":"4961",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Mumbai",
"name":"Ankush patil",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 20:20:20"
,
"id":"4960",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Delhi",
"name":"ER Vikash Thakur",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 20:17:32"
,
"id":"4957",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Kolkata",
"name":"Shiladitya Ghosh",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 20:09:44"
,
"id":"4956",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Delhi",
"name":"Vikash",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 20:08:44"
,
"id":"4953",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Rishikesh",
"name":"Rahul",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 19:51:17"
,
"id":"4950",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Pune",
"name":"Abhishek",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 19:43:27"
,
"id":"4949",
"topic":"Topic",
"sub_topic":"Sub Topic",
"city":"Chandigarh ",
"name":"K Singh ",
"quotes":"0",
"credits":"10",
"timestamp":"2021-01-05 19:40:36"
]
我的片段：
public class LeadsFragment extends Fragment
RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;
private static final String url = "myurl";
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
View view = inflater.inflate(R.layout.fragment_leads, container, false);
recyclerView = view.findViewById(R.id.recyclerview);
StringRequest stringRequest = new StringRequest(url, new Response.Listener<String>()
@Override
public void onResponse(String response)
GsonBuilder gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();
LeadModel leadsModelList = gson.fromJson(response, LeadModel.class);
recyclerView.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);
LeadsAdapter leadsAdapter = new LeadsAdapter(getContext(), leadsModelList, recyclerView);
recyclerView.setAdapter(leadsAdapter);
, new Response.ErrorListener()
@Override
public void onErrorResponse(VolleyError error)
Toast.makeText(getContext(), error.toString(), Toast.LENGTH_SHORT).show();
);
RequestQueue queue = Volley.newRequestQueue(getContext());
queue.add(stringRequest);
return view;
我的适配器：
public class LeadsAdapter extends RecyclerView.Adapter<LeadsAdapter.ViewHolder>
Context context;
LeadModel leadsModelList;
RecyclerView recyclerView;
final View.OnClickListener onClickListener = new MyOnClickListener();
public LeadsAdapter(Context context, LeadModel leadsModelList, RecyclerView recyclerView)
this.context = context;
this.leadsModelList = leadsModelList;
this.recyclerView = recyclerView;
public static class ViewHolder extends RecyclerView.ViewHolder
TextView name, topic, sub_topic, city, credits, quotes;
public ViewHolder(@NonNull View itemView)
super(itemView);
name = itemView.findViewById(R.id.tvName);
topic = itemView.findViewById(R.id.tvTopic);
sub_topic = itemView.findViewById(R.id.tvSubTopic);
city = itemView.findViewById(R.id.tvLocation);
credits = itemView.findViewById(R.id.tvCredits);
quotes = itemView.findViewById(R.id.tvQuotes);
@NonNull
@Override
public LeadsAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType)
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.lead_card, viewGroup, false);
view.setOnClickListener(onClickListener);
LeadsAdapter.ViewHolder viewHolder = new LeadsAdapter.ViewHolder(view);
return viewHolder;
@Override
public void onBindViewHolder(@NonNull LeadsAdapter.ViewHolder viewHolder, int position)
viewHolder.name.setText(leadsModelList.getData().get(position).getName());
viewHolder.topic.setText(leadsModelList.getData().get(position).getTopic());
viewHolder.sub_topic.setText(leadsModelList.getData().get(position).getSubTopic());
viewHolder.city.setText(leadsModelList.getData().get(position).getCity());
viewHolder.credits.setText(leadsModelList.getData().get(position).getCredits()+ " Credits");
// viewHolder.quotes.setText(leadsModelList.getData().get(position).getQuotes()+"/"+ leadsModelList.getMeta().getTotalQuotes() +" Quotes");
@Override
public int getItemCount()
return leadsModelList.getData().size();
模型类：
public class LeadModel
@SerializedName("leadsMeta")
@Expose
private LeadsMeta leadsMeta;
@SerializedName("data")
@Expose
private List<LeadsData> data = null;
public LeadsMeta getMeta()
return leadsMeta;
public void setMeta(LeadsMeta leadsMeta)
this.leadsMeta = leadsMeta;
public List<LeadsData> getData()
return data;
public void setData(List<LeadsData> data)
this.data = data;
元类
public class LeadsMeta
@SerializedName("code")
@Expose
private Integer code;
@SerializedName("message")
@Expose
private String message;
@SerializedName("total_pages")
@Expose
private Integer totalPages;
@SerializedName("current_page")
@Expose
private Integer currentPage;
@SerializedName("total_items")
@Expose
private Integer totalItems;
@SerializedName("total_quotes")
@Expose
private Integer totalQuotes;
public Integer getCode()
return code;
public void setCode(Integer code)
this.code = code;
public String getMessage()
return message;
public void setMessage(String message)
this.message = message;
public Integer getTotalPages()
return totalPages;
public void setTotalPages(Integer totalPages)
this.totalPages = totalPages;
public Integer getCurrentPage()
return currentPage;
public void setCurrentPage(Integer currentPage)
this.currentPage = currentPage;
public Integer getTotalItems()
return totalItems;
public void setTotalItems(Integer totalItems)
this.totalItems = totalItems;
public Integer getTotalQuotes()
return totalQuotes;
public void setTotalQuotes(Integer totalQuotes)
this.totalQuotes = totalQuotes;
数据类
public class LeadsData
@SerializedName("id")
@Expose
private String id;
@SerializedName("topic")
@Expose
private String topic;
@SerializedName("sub_topic")
@Expose
private String subTopic;
@SerializedName("city")
@Expose
private String city;
@SerializedName("name")
@Expose
private String name;
@SerializedName("quotes")
@Expose
private String quotes;
@SerializedName("credits")
@Expose
private String credits;
@SerializedName("timestamp")
@Expose
private String timestamp;
public String getId()
return id;
public void setId(String id)
this.id = id;
public String getTopic()
return topic;
public void setTopic(String topic)
this.topic = topic;
public String getSubTopic()
return subTopic;
public void setSubTopic(String subTopic)
this.subTopic = subTopic;
public String getCity()
return city;
public void setCity(String city)
this.city = city;
public String getName()
return name;
public void setName(String name)
this.name = name;
public String getQuotes()
return quotes;
public void setQuotes(String quotes)
this.quotes = quotes;
public String getCredits()
return credits;
public void setCredits(String credits)
this.credits = credits;
public String getTimestamp()
return timestamp;
public void setTimestamp(String timestamp)
this.timestamp = timestamp;
【问题讨论】：
【参考方案1】：“元”对象的序列化名称在您的 LeadModel 类中应该是“元”。
public class LeadModel
//@SerializedName("leadsMeta")
@SerializedName("meta")
@Expose
private LeadsMeta leadsMeta;
【讨论】：
【参考方案2】：-
我想显示下一页数据
请在您的回收站视图中使用recyclerView.addOnScrollListener。当用户滚动并到达最后一项时，您需要加载更多 10 项并将列表附加到现有列表中
public class LeadsFragment extends Fragment
RecyclerView recyclerView;
RecyclerView.LayoutManager layoutManager;
private static final String url = "myurl";
boolean isLoading = false; // For Tracking
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
......
........
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener()
@Override
public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState)
super.onScrollStateChanged(recyclerView, newState);
@Override
public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy)
super.onScrolled(recyclerView, dx, dy);
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
if (!isLoading)
if (linearLayoutManager != null && linearLayoutManager.findLastCompletelyVisibleItemPosition() == yourList.size() - 1)
// Last item reached
loadMore(); // Note this method
isLoading = true;
);
private void loadMore()
// Make http Request
// append the new data to LeadsData
// notifyAdapter items changed
// set isLoading = false
-
我在空对象引用上面临“LeadsMeta.getTotalQuotes()'”
这是因为您在 LeadModel 中的序列化名称应该与您的 json 一致
@SerializedName("meta")
【讨论】：
我在@SerializedName("meta") 名称中犯了一个多么愚蠢的错误......谢谢。 完成所有事情。但有一点不清楚。如何附加数据并通知适配器 // 将新数据附加到 LeadsData // notifyAdapter 项目已更改【参考方案3】：第一个问题：
您需要检查this 代码。在 MainActivity.java 类中，这里有一个方法 loadMore()。在您的情况下，您需要进行 API 调用以加载 10 个以上的项目，然后通知您的适配器您有新项目，它会将它们加载到您的列表中。这就是你如何使用无穷无尽的项目来实现你的recyclerview。
第二个问题：
您应该将 @SerializedName 中的 leadsMeta 更改为 meta。 这是您编辑的课程：
public class LeadModel
@SerializedName("meta")
@Expose
private LeadsMeta leadsMeta;
@SerializedName("data")
@Expose
private List<LeadsData> data = null;
public LeadsMeta getMeta()
return leadsMeta;
public void setMeta(LeadsMeta leadsMeta)
this.leadsMeta = leadsMeta;
public List<LeadsData> getData()
return data;
public void setData(List<LeadsData> data)
this.data = data;
【讨论】：
我正在分享link，其中有关于我在答案中分享的代码的教程。快乐编码:)以上是关于如何在 Android Recyclerview 中显示 JSON 数组中包含的 JSON 对象的主要内容，如果未能解决你的问题，请参考以下文章
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