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Listview 数据不显示在recyclerview中，但在关闭和打开后显示数据列表

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Listview 数据不显示在recyclerview中，但在关闭和打开后显示数据列表,listview,android-recyclerview,android-volley,android-adapter,Listview,Android Recyclerview,Android Volley,Android Adapter,我正在开发一个应用程序，我正在使用volley库从服务器获取数据并显示在RecyclerView中。。这里我使用了四个标签 问题在于，首先通过从服务器获取数据来运行要显示的元素列表，数据加载并添加到列表中，但RecyclerView从不显示它。当我关闭显示器并将其返回时，数据将列在RecyclerView 谁能帮帮我 下面是MyAdapter.java public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHol

我正在开发一个应用程序，我正在使用volley库从服务器获取数据并显示在
RecyclerView
中。。这里我使用了四个标签

问题在于，首先通过从服务器获取数据来运行要显示的元素列表，数据加载并添加到列表中，但
RecyclerView
从不显示它。当我关闭显示器并将其返回时，数据将列在
RecyclerView

谁能帮帮我

下面是
MyAdapter.java

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

private ImageLoader mImageLoader;
private Context context;

ArrayList<Coupon> couponArrayList = new ArrayList<>();

public MyAdapter(Context context,ArrayList<Coupon> couponArrayList)
{
    this.couponArrayList=couponArrayList;
    this.context=context;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    final View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.offer_row,parent,false);
    ViewHolder viewHolder = new ViewHolder(view);

    viewHolder.relativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            TextView redUrl = (TextView)view.findViewById(R.id.offer_url);
            String postUrl = redUrl.getText().toString();
            Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(postUrl));
            Intent browserChooserIntent = Intent.createChooser(intent , "Choose browser of your choice");
            context.startActivity(browserChooserIntent);
        }
    });

    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    Coupon coupon = couponArrayList.get(position);
    holder.title.setText(coupon.getTitle());
    holder.name.setText(coupon.getName());
    holder.coupon.setText(coupon.getCoupon());
    holder.expiry.setText(coupon.getExpiry());
    holder.url.setText(coupon.getLink());

    //Image loading using singleton class
    mImageLoader = MySingleton.getInstance(context).getImageLoader();
    holder.image.setImageUrl(coupon.getImage(),mImageLoader);
    holder.image.setDefaultImageResId(R.drawable.placeholder_image);
}

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
    super.onAttachedToRecyclerView(recyclerView);
}
public void remove(ContactsContract.Contacts.Data data) {
    int position = couponArrayList.indexOf(data);
    couponArrayList.remove(position);
    notifyItemRemoved(position);
}

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

public static class ViewHolder extends RecyclerView.ViewHolder{
    NetworkImageView image;
    RelativeLayout relativeLayout;
    TextView title,name,coupon,expiry,url;

    public ViewHolder(View itemView) {
        super(itemView);
        this.image = (NetworkImageView)itemView.findViewById(R.id.offer_image);
        this.title = (TextView)itemView.findViewById(R.id.offer_title);
        this.name = (TextView)itemView.findViewById(R.id.offer_name);
        this.coupon = (TextView)itemView.findViewById(R.id.coupon_code);
        this.expiry = (TextView)itemView.findViewById(R.id.expiry_date);
        this.url = (TextView)itemView.findViewById(R.id.offer_url);
        this.relativeLayout = (RelativeLayout)itemView.findViewById(R.id.relLayout);

        //make sure it is clickable
        itemView.setClickable(true);
    }
}

public class BackgroundTask {
    Context context;
    RequestQueue queue;
    public static final String KEY_TITLE="coupon_title";
    public static final String KEY_NAME="offer_name";
    public static final String KEY_CODE="coupon_code";
    public static final String KEY_IMAGE="store_image";
    public static final String KEY_EXPIRY="coupon_expiry";
    public static final String KEY_POSTURL="store_link";

    private ImageLoader mImageLoader;
    ArrayList<Coupon> arrayList = new ArrayList<>();
    public static final String json_url="https://tools.vcommission.com/api/coupons.php?apikey=xxxxxxxxxx";

    public BackgroundTask(Context context) {
        this.context = context;
    }

    public ArrayList<Coupon> getList()
    {
        final JsonArrayRequest  jsonArrayRequest=new JsonArrayRequest(Request.Method.POST, json_url,null,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        int count=0;
                        while (count<response.length())
                        {
                            try {
                                JSONObject jsonObject= response.getJSONObject(count);
                                Coupon coupon = new Coupon(jsonObject.getString(KEY_TITLE),
                                        jsonObject.getString(KEY_NAME),
                                        jsonObject.getString(KEY_CODE),
                                        jsonObject.getString(KEY_IMAGE),
                                        jsonObject.getString(KEY_EXPIRY),
                                        jsonObject.getString(KEY_POSTURL));

                                arrayList.add(coupon);
                                count++;

                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(context,"No internet connection...!!!",Toast.LENGTH_LONG).show();
                error.printStackTrace();
            }
        });
        MySingleton.getInstance(context).addToRequestQueue(jsonArrayRequest);

        return arrayList;
    }
}
最后是
Backgroundtask.java

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

private ImageLoader mImageLoader;
private Context context;

ArrayList<Coupon> couponArrayList = new ArrayList<>();

public MyAdapter(Context context,ArrayList<Coupon> couponArrayList)
{
    this.couponArrayList=couponArrayList;
    this.context=context;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    final View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.offer_row,parent,false);
    ViewHolder viewHolder = new ViewHolder(view);

    viewHolder.relativeLayout.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            TextView redUrl = (TextView)view.findViewById(R.id.offer_url);
            String postUrl = redUrl.getText().toString();
            Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(postUrl));
            Intent browserChooserIntent = Intent.createChooser(intent , "Choose browser of your choice");
            context.startActivity(browserChooserIntent);
        }
    });

    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    Coupon coupon = couponArrayList.get(position);
    holder.title.setText(coupon.getTitle());
    holder.name.setText(coupon.getName());
    holder.coupon.setText(coupon.getCoupon());
    holder.expiry.setText(coupon.getExpiry());
    holder.url.setText(coupon.getLink());

    //Image loading using singleton class
    mImageLoader = MySingleton.getInstance(context).getImageLoader();
    holder.image.setImageUrl(coupon.getImage(),mImageLoader);
    holder.image.setDefaultImageResId(R.drawable.placeholder_image);
}

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
    super.onAttachedToRecyclerView(recyclerView);
}
public void remove(ContactsContract.Contacts.Data data) {
    int position = couponArrayList.indexOf(data);
    couponArrayList.remove(position);
    notifyItemRemoved(position);
}

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

public static class ViewHolder extends RecyclerView.ViewHolder{
    NetworkImageView image;
    RelativeLayout relativeLayout;
    TextView title,name,coupon,expiry,url;

    public ViewHolder(View itemView) {
        super(itemView);
        this.image = (NetworkImageView)itemView.findViewById(R.id.offer_image);
        this.title = (TextView)itemView.findViewById(R.id.offer_title);
        this.name = (TextView)itemView.findViewById(R.id.offer_name);
        this.coupon = (TextView)itemView.findViewById(R.id.coupon_code);
        this.expiry = (TextView)itemView.findViewById(R.id.expiry_date);
        this.url = (TextView)itemView.findViewById(R.id.offer_url);
        this.relativeLayout = (RelativeLayout)itemView.findViewById(R.id.relLayout);

        //make sure it is clickable
        itemView.setClickable(true);
    }
}

public class BackgroundTask {
    Context context;
    RequestQueue queue;
    public static final String KEY_TITLE="coupon_title";
    public static final String KEY_NAME="offer_name";
    public static final String KEY_CODE="coupon_code";
    public static final String KEY_IMAGE="store_image";
    public static final String KEY_EXPIRY="coupon_expiry";
    public static final String KEY_POSTURL="store_link";

    private ImageLoader mImageLoader;
    ArrayList<Coupon> arrayList = new ArrayList<>();
    public static final String json_url="https://tools.vcommission.com/api/coupons.php?apikey=xxxxxxxxxx";

    public BackgroundTask(Context context) {
        this.context = context;
    }

    public ArrayList<Coupon> getList()
    {
        final JsonArrayRequest  jsonArrayRequest=new JsonArrayRequest(Request.Method.POST, json_url,null,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        int count=0;
                        while (count<response.length())
                        {
                            try {
                                JSONObject jsonObject= response.getJSONObject(count);
                                Coupon coupon = new Coupon(jsonObject.getString(KEY_TITLE),
                                        jsonObject.getString(KEY_NAME),
                                        jsonObject.getString(KEY_CODE),
                                        jsonObject.getString(KEY_IMAGE),
                                        jsonObject.getString(KEY_EXPIRY),
                                        jsonObject.getString(KEY_POSTURL));

                                arrayList.add(coupon);
                                count++;

                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(context,"No internet connection...!!!",Toast.LENGTH_LONG).show();
                error.printStackTrace();
            }
        });
        MySingleton.getInstance(context).addToRequestQueue(jsonArrayRequest);

        return arrayList;
    }
}

公共类背景任务{
语境；
请求队列；
公共静态最终字符串键\u TITLE=“优惠券\u TITLE”；
公共静态最终字符串键\u NAME=“offer\u NAME”；
公共静态最终字符串键\u CODE=“优惠券\u CODE”；
公共静态最终字符串KEY\u IMAGE=“store\u IMAGE”；
公共静态最终字符串键\u EXPIRY=“优惠券\u EXPIRY”；
公共静态最终字符串键\u postrl=“存储链接”；
私有图像加载器；
ArrayList ArrayList=新的ArrayList（）；
公共静态最终字符串json_url=”https://tools.vcommission.com/api/coupons.php?apikey=xxxxxxxxxx";
公共背景任务（上下文）{
this.context=上下文；
}
公共ArrayList getList（）
{
final JsonArrayRequest JsonArrayRequest=新的JsonArrayRequest（Request.Method.POST，json_url，null，
新的Response.Listener（）{
@凌驾
公共void onResponse（JSONArray响应）{
整数计数=0；

而（count您的
RecyclerView
第二次加载正确。因此适配器没有问题

问题是从服务器获得响应后，您没有在
适配器上调用
notifyDatasetChanged
。您还存在一些其他基本问题。我正在尝试稍微修改您的代码，以便您更容易理解问题

< >我只是从AlpOffice中添加必要的部分。java < /COD>。这里你可以考虑的是，在使用截击时保持同一个类的网络调用。当我们从服务器得到响应时，在<代码>适配器<代码>中更容易地调用<代码> NoTIFYDATABETHORKEX/<代码>。< /P>

public class AllOffers extends Fragment {
    RequestQueue queue;
    RecyclerView recyclerView;
    RecyclerView.Adapter adapter;
    RecyclerView.LayoutManager layoutManager;
    ArrayList<Coupon> arrayList = new ArrayList<>();

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.alloffers, container, false);

        // Setup your RecyclerView here
        recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
        layoutManager = new LinearLayoutManager(getContext());
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.addItemDecoration(new DividerItemDecoration(getContext(), LinearLayoutManager.VERTICAL));

        // Set the adapter before the network call
        adapter = new MyAdapter(getContext(), arrayList);
        recyclerView.setAdapter(adapter);

        // Move network call here
        final JsonArrayRequest  jsonArrayRequest=new JsonArrayRequest(Request.Method.POST, json_url,null,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        int count=0;
                        while (count<response.length())
                        {
                            try {
                                JSONObject jsonObject= response.getJSONObject(count);
                                Coupon coupon = new Coupon(jsonObject.getString(KEY_TITLE),
                                        jsonObject.getString(KEY_NAME),
                                        jsonObject.getString(KEY_CODE),
                                        jsonObject.getString(KEY_IMAGE),
                                        jsonObject.getString(KEY_EXPIRY),
                                        jsonObject.getString(KEY_POSTURL));

                                arrayList.add(coupon);
                                count++;

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

                        // Call notifyDatasetChanged on adapter so that the newly added items in the list takes effect in your RecyclerView
                        adapter.notifyDatasetChanged();

                    }
                }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                Toast.makeText(context,"No internet connection...!!!",Toast.LENGTH_LONG).show();
                error.printStackTrace();
            }
        });

        return view;
    }
}



公共类alloffer扩展了片段{
请求队列；
回收视图回收视图；
RecyclerView.适配器；
RecyclerView.LayoutManager LayoutManager；
ArrayList ArrayList=新的ArrayList（）；
@凌驾
创建视图上的公共视图（布局、充气机、视图组容器、，
Bundle savedInstanceState）{
视图=充气机。充气（右布局。alloffers，容器，假）；
//在此处设置您的RecyclerView
recyclerView=（recyclerView）view.findViewById（R.id.recyclerView）；
layoutManager=新的LinearLayoutManager（getContext（））；
recyclerView.setLayoutManager（layoutManager）；
addItemDecoration（新的DividerItemDecoration（getContext（），LinearLayoutManager.VERTICAL））；
//在网络调用之前设置适配器
adapter=newmyadapter（getContext（），arrayList）；
recyclerView.setAdapter（适配器）；
//移动网络呼叫此处
final JsonArrayRequest JsonArrayRequest=新的JsonArrayRequest（Request.Method.POST，json_url，null，
新的Response.Listener（）{
@凌驾
公共void onResponse（JSONArray响应）{
整数计数=0；

而（count您的
RecyclerView
第二次加载正确。因此适配器没有问题

问题是从服务器获得响应后，您没有在
适配器上调用
notifyDatasetChanged
。您还存在一些其他基本问题。我正在尝试稍微修改您的代码，以便您更容易理解问题

< >我只是从AlpOffice中添加必要的部分。java < /COD>。这里你可以考虑的是，在使用截击时保持同一个类的网络调用。当我们从服务器得到响应时，在<代码>适配器<代码>中更容易地调用<代码> NoTIFYDATABETHORKEX/<代码>。< /P>

public class AllOffers extends Fragment {
    RequestQueue queue;
    RecyclerView recyclerView;
    RecyclerView.Adapter adapter;
    RecyclerView.LayoutManager layoutManager;
    ArrayList<Coupon> arrayList = new ArrayList<>();

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.alloffers, container, false);

        // Setup your RecyclerView here
        recyclerView = (RecyclerView) view.findViewById(R.id.recyclerView);
        layoutManager = new LinearLayoutManager(getContext());
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.addItemDecoration(new DividerItemDecoration(getContext(), LinearLayoutManager.VERTICAL));

        // Set the adapter before the network call
        adapter = new MyAdapter(getContext(), arrayList);
        recyclerView.setAdapter(adapter);

        // Move network call here
        final JsonArrayRequest  jsonArrayRequest=new JsonArrayRequest(Request.Method.POST, json_url,null,
                new Response.Listener<JSONArray>() {
                    @Override
                    public void onResponse(JSONArray response) {
                        int count=0;
                        while (count<response.length())
                        {
                            try {
                                JSONObject jsonObject= response.getJSONObject(count);
                                Coupon coupon = new Coupon(jsonObject.getString(KEY_TITLE),
                                        jsonObject.getString(KEY_NAME),
                                        jsonObject.getString(KEY_CODE),
                                        jsonObject.getString(KEY_IMAGE),
                                        jsonObject.getString(KEY_EXPIRY),
                                        jsonObject.getString(KEY_POSTURL));

                                arrayList.add(coupon);
                                count++;

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

                        // Call notifyDatasetChanged on adapter so that the newly added items in the list takes effect in your RecyclerView
                        adapter.notifyDatasetChanged();

                    }
                }, new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                Toast.makeText(context,"No internet connection...!!!",Toast.LENGTH_LONG).show();
                error.printStackTrace();
            }
        });

        return view;
    }
}



公共类alloffer扩展了片段{
请求队列；
回收视图回收视图；
RecyclerView.适配器；
RecyclerView.LayoutManager LayoutManager；
ArrayList ArrayList=新的ArrayList（）；
@凌驾
创建视图上的公共视图（布局、充气机、视图组容器、，
Bundle savedInstanceState）{
视图=充气机。充气（右布局。alloffers，容器，假）；
//在此处设置您的RecyclerView
recyclerView=（recyclerView）view.findViewById（R.id.recyclerView）；
layoutManager=新的LinearLayoutManager（getContext（））；
recyclerView.setLayoutManager（layoutManager）；
addItemDecoration（新的DividerItemDecoration（getContext（），LinearLayoutManager.VERTICAL））；
//在网络调用之前设置适配器
adapter=newmyadapter（getContext（），arrayList）；
recyclerView.setAdapter（适配器）；
//移动网络呼叫此处
final JsonArrayRequest JsonArrayRequest=新的JsonArrayRequest（Request.Method.POST，json_url，null，
新的Response.Listener（）{
@凌驾
公共void onResponse（JSONArray响应）{
整数计数=0；
而