更新的 json 数据未在 android 中显示
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【中文标题】更新的 json 数据未在 android 中显示【英文标题】：updated json data not showing in android 【发布时间】：2021-12-13 06:49:17 【问题描述】：从我的服务器检索 json 数据。第一次在我的应用程序中显示数据。但是在更新新数据时，它没有显示。只显示旧数据..当我从应用程序中清除缓存时，它会显示更新的数据。但我想同时显示实时数据。我必须做什么？请帮帮我。
RecyclerViewAdapter.java
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.MyViewHolder>
private Context mContext ;
private List<Anime> mData ;
RequestOptions option;
public RecyclerViewAdapter(Context mContext, List<Anime> mData)
this.mContext = mContext;
this.mData = mData;
// Request option for Glide
option = new RequestOptions().centerCrop().placeholder(R.drawable.loading_shape).error(R.drawable.loading_shape);
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType)
View view ;
LayoutInflater inflater = LayoutInflater.from(mContext);
view = inflater.inflate(R.layout.anime_row_item,parent,false) ;
final MyViewHolder viewHolder = new MyViewHolder(view) ;
viewHolder.view_container.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
Intent i = new Intent(mContext, Read.class);
i.putExtra("news_title",mData.get(viewHolder.getAdapterPosition()).getName());
i.putExtra("news_description",mData.get(viewHolder.getAdapterPosition()).getDescription());
i.putExtra("anime_studio",mData.get(viewHolder.getAdapterPosition()).getAuthor());
i.putExtra("anime_category",mData.get(viewHolder.getAdapterPosition()).getCategorie());
i.putExtra("anime_img",mData.get(viewHolder.getAdapterPosition()).getImage_url());
mContext.startActivity(i);
);
return viewHolder;
@Override
public void onBindViewHolder(MyViewHolder holder, int position)
holder.post_title.setText(mData.get(position).getName());
holder.date.setText(mData.get(position).getDate());
holder.author.setText(mData.get(position).getAuthor());
holder.cat_name.setText(mData.get(position).getCategorie());
// Load Image from the internet and set it into Imageview using Glide
Glide.with(mContext).load(mData.get(position).getImage_url()).apply(option).into(holder.thumbnail);
@Override
public int getItemCount()
return mData.size();
public static class MyViewHolder extends RecyclerView.ViewHolder
TextView post_title ;
TextView date ;
TextView author ;
TextView cat_name;
ImageView thumbnail;
LinearLayout view_container;
public MyViewHolder(View itemView)
super(itemView);
view_container = itemView.findViewById(R.id.container);
post_title = itemView.findViewById(R.id.post_title);
cat_name = itemView.findViewById(R.id.cat_name);
date = itemView.findViewById(R.id.date);
author = itemView.findViewById(R.id.author);
thumbnail = itemView.findViewById(R.id.thumbnail);
Home.java
public class Home extends Fragment
private final String JSON_URL = "https://mywebsite.org/news/api.php";
private JsonArrayRequest request ;
private RequestQueue requestQueue ;
private List<Anime> lstAnime ;
private RecyclerView recyclerView ;
ProgressBar loading;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
View root = inflater.inflate(R.layout.fragment_home, container, false);
loading = (ProgressBar)root.findViewById(R.id.bar);
loading.setMax(100);
lstAnime = new ArrayList<>() ;
recyclerView = root.findViewById(R.id.recyclerviewid);
jsonrequest();
return root;
private void jsonrequest()
request = new JsonArrayRequest(JSON_URL, new Response.Listener<JSONArray>()
@Override
public void onResponse(JSONArray response)
loading.setVisibility(View.GONE);
JSONObject jsonObject = null ;
for (int i = 0 ; i < response.length(); i++ )
try
jsonObject = response.getJSONObject(i) ;
Anime anime = new Anime() ;
anime.setName(jsonObject.getString("title"));
anime.setDescription(jsonObject.getString("description"));
anime.setDate(jsonObject.getString("date"));
anime.setCategorie(jsonObject.getString("category"));
anime.setAuthor(jsonObject.getString("admin"));
anime.setImage_url(jsonObject.getString("thumbnail"));
lstAnime.add(anime);
catch (JSONException e)
e.printStackTrace();
setuprecyclerview(lstAnime);
, new Response.ErrorListener()
@Override
public void onErrorResponse(VolleyError error)
if (error instanceof TimeoutError || error instanceof NoConnectionError)
//This indicates that the request has either time out or there is no connection
Toast.makeText(getActivity(), "TimeOut...! No Internet",
Toast.LENGTH_LONG).show();
else if (error instanceof AuthFailureError)
// Error indicating that there was an Authentication Failure while performing the request
Toast.makeText(getActivity(), "Failed To Receive Data",
Toast.LENGTH_LONG).show();
else if (error instanceof ServerError)
//Indicates that the server responded with a error response
Toast.makeText(getActivity(), "Our Server Under Maintenance",
Toast.LENGTH_LONG).show();
else if (error instanceof NetworkError)
//Indicates that there was network error while performing the request
Toast.makeText(getActivity(), "Network Not Responding",
Toast.LENGTH_LONG).show();
else if (error instanceof ParseError)
// Indicates that the server response could not be parsed
Toast.makeText(getActivity(), "Please Reload Again!",
Toast.LENGTH_LONG).show();
);
requestQueue = Volley.newRequestQueue(getActivity());
requestQueue.add(request);
private void setuprecyclerview(List<Anime> lstAnime)
RecyclerViewAdapter myadapter = new RecyclerViewAdapter(getActivity(),lstAnime);
recyclerView.setAdapter(myadapter);
// grid columns is 2
GridLayoutManager manager = new GridLayoutManager(getActivity(), 2);
manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup()
@Override
public int getSpanSize(int position)
// 0 is first one and 9 is first one all of others are 2 columns
if (position == 0 || position == 9)
return 2;
return 1;
);
recyclerView.setItemAnimator(null);
recyclerView.setHasFixedSize(true);
recyclerView.setAdapter(myadapter);
recyclerView.setLayoutManager(manager);
public interface OnFragmentInteractionListener
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
fragment_home.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipeContainer"
android:layout_
android:layout_>
<androidx.core.widget.NestedScrollView
android:layout_
android:layout_
xmlns:android="http://schemas.android.com/apk/res/android">
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".fragments.Home"
android:orientation="vertical">
<!-- TODO: Update blank fragment layout -->
<ProgressBar
android:layout_
android:layout_
android:layout_gravity="center"
android:id="@+id/bar"/>
<androidx.recyclerview.widget.RecyclerView
android:layout_
android:layout_
android:id="@+id/recyclerviewid">
</androidx.recyclerview.widget.RecyclerView>
</LinearLayout>
</androidx.core.widget.NestedScrollView>
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
对不起，我的英语不好。 提前致谢。
【问题讨论】：
您的回收站视图没有显示更新的数据吗？ 你如何“更新数据”？我看到对服务器的请求只在“onCreateView（）”中发出一次，所以只有在创建片段时才会发出请求。因此，如果您更新服务器的数据，您必须重新执行请求...... @emandt 你能帮我做吗？我不知道如何重新执行请求。请通过编辑我的代码发布答案，这将对我和其他人有所帮助。 @Danish no...只显示旧数据...但是当我清除缓存时，然后显示新数据。但我想在更新新数据时立即显示。 分享你的回收视图适配器代码。 【参考方案1】：在您的 jsonrequest() 方法中使用 notifyDataSetChanged 通知您的回收站视图。使用 requestQueue.getCache().clear() 清除缓存； 检查以下代码：
public class Home extends Fragment
private final String JSON_URL = "https://mywebsite.org/news/api.php";
private JsonArrayRequest request ;
private RequestQueue requestQueue ;
private List<Anime> lstAnime ;
private RecyclerView recyclerView ;
ProgressBar loading;
RecyclerViewAdapter myadapter;
**SwipeRefreshLayout swipeRefreshLayout;**
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
View root = inflater.inflate(R.layout.fragment_home, container, false);
loading = (ProgressBar)root.findViewById(R.id.bar);
loading.setMax(100);
lstAnime = new ArrayList<>() ;
recyclerView = root.findViewById(R.id.recyclerviewid);
jsonrequest();
setuprecyclerview(lstAnime);
**swipeRefreshLayout=view.findViewById(R.id.swipeContainer);
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener()
@Override
public void onRefresh()
jsonrequest();
myAdapter.notifyDataSetChanged();
swipeRefreshLayout.setRefreshing(false);
);**
return root;
private void jsonrequest()
request = new JsonArrayRequest(JSON_URL, new Response.Listener<JSONArray>()
@Override
public void onResponse(JSONArray response)
loading.setVisibility(View.GONE);
JSONObject jsonObject = null ;
for (int i = 0 ; i < response.length(); i++ )
try
jsonObject = response.getJSONObject(i) ;
Anime anime = new Anime() ;
anime.setName(jsonObject.getString("title"));
anime.setDescription(jsonObject.getString("description"));
anime.setDate(jsonObject.getString("date"));
anime.setCategorie(jsonObject.getString("category"));
anime.setAuthor(jsonObject.getString("admin"));
anime.setImage_url(jsonObject.getString("thumbnail"));
lstAnime.add(anime);
catch (JSONException e)
e.printStackTrace();
if(myadapter != null)
myadapter.notifyDataSetChanged();
, new Response.ErrorListener()
@Override
public void onErrorResponse(VolleyError error)
if (error instanceof TimeoutError || error instanceof NoConnectionError)
//This indicates that the request has either time out or there is no connection
Toast.makeText(getActivity(), "TimeOut...! No Internet",
Toast.LENGTH_LONG).show();
else if (error instanceof AuthFailureError)
// Error indicating that there was an Authentication Failure while performing the request
Toast.makeText(getActivity(), "Failed To Receive Data",
Toast.LENGTH_LONG).show();
else if (error instanceof ServerError)
//Indicates that the server responded with a error response
Toast.makeText(getActivity(), "Our Server Under Maintenance",
Toast.LENGTH_LONG).show();
else if (error instanceof NetworkError)
//Indicates that there was network error while performing the request
Toast.makeText(getActivity(), "Network Not Responding",
Toast.LENGTH_LONG).show();
else if (error instanceof ParseError)
// Indicates that the server response could not be parsed
Toast.makeText(getActivity(), "Please Reload Again!",
Toast.LENGTH_LONG).show();
);
requestQueue = Volley.newRequestQueue(getActivity());
requestQueue.getCache().clear();//add this line
requestQueue.add(request);
private void setuprecyclerview(List<Anime> lstAnime)
myadapter = new RecyclerViewAdapter(getActivity(),lstAnime);
recyclerView.setAdapter(myadapter);
// grid columns is 2
GridLayoutManager manager = new GridLayoutManager(getActivity(), 2);
manager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup()
@Override
public int getSpanSize(int position)
// 0 is first one and 9 is first one all of others are 2 columns
if (position == 0 || position == 9)
return 2;
return 1;
);
recyclerView.setItemAnimator(null);
recyclerView.setHasFixedSize(true);
recyclerView.setAdapter(myadapter);
recyclerView.setLayoutManager(manager);
public interface OnFragmentInteractionListener
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
同样在你的 recyclerviewadapter.java 中添加这一行到 recycler 适配器构造函数：
public RecyclerViewAdapter(Context mContext, List<Anime> mData)
this.mContext = mContext;
this.mData = mData;
this.notifyDataSetChanged();
// Request option for Glide
option = new RequestOptions().centerCrop().placeholder(R.drawable.loading_shape).error(R.drawable.loading_shape);
从 xml 文件中删除嵌套的滚动视图：
<?xml version="1.0" encoding="utf-8"?>
<androidx.swiperefreshlayout.widget.SwipeRefreshLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/swipeContainer"
android:layout_
android:layout_>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".fragments.Home"
android:orientation="vertical">
<!-- TODO: Update blank fragment layout -->
<ProgressBar
android:layout_
android:layout_
android:layout_gravity="center"
android:id="@+id/bar"/>
<androidx.recyclerview.widget.RecyclerView
android:layout_
android:layout_
android:id="@+id/recview">
</androidx.recyclerview.widget.RecyclerView>
</LinearLayout>
</androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
【讨论】：
它不工作。同样的问题。 你试过清除浏览器缓存吗？ 哪个浏览器？如果我清除应用程序缓存，它会显示新数据。但用户不会每次都这样做。 添加后 this.notifyDataSetChanged();到我的 recyclerviewadapter.java，它也不起作用。 实际上，当您重新启动应用程序时，数据正在从缓存中加载，而缓存实际上保存着您的旧数据。以上是关于更新的 json 数据未在 android 中显示的主要内容，如果未能解决你的问题，请参考以下文章