Fragment, Volley and RecyclerView JSON

Question

我希望那里有人能帮我解决问题。我有一个使用片段的Android应用程序。我想使用Volley从JSON文件下载数据。程序不会抛出任何错误，但CardView不会显示有序的数据。我看了其他有类似问题的话题，但我坐了很长时间，什么都没发生。

AdapterZabytki.java

package eu.aisen.kamil.miejskiprzewodnik;
import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.squareup.picasso.Picasso;
import java.util.List;
import zabytki.Zabytki;
public class AdapterZabytki extends RecyclerView.Adapter<AdapterZabytki.ViewHolder> {
private List<Zabytek>list_data;
private Zabytki context;
public AdapterZabytki(List<Zabytek> list_data, Zabytki context) {
this.list_data = list_data;
this.context = context;
}
@Override
public AdapterZabytki.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
CardView view= (CardView) LayoutInflater.from(parent.getContext()).inflate(R.layout.obiectcard,parent,false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Zabytek zabytek = list_data.get(position);
Picasso.get()
.load(zabytek
.getImage_url())
.into(holder.img);
holder.txtname.setText(zabytek.getName());
}
@Override
public int getItemCount() {
return list_data.size();
}
public class ViewHolder extends RecyclerView.ViewHolder{
private ImageView img;
private TextView txtname;
public ViewHolder(View view) {
super(view);
img=(ImageView)itemView.findViewById(R.id.info_image);
txtname=(TextView)itemView.findViewById(R.id.info_text);
}
}
}

Zabytek.java

package eu.aisen.kamil.miejskiprzewodnik;

public class Zabytek {
private String name;
private String image_url;
private String opis;
public Zabytek(String name, String image_url, String opis) {
this.name = name;
this.image_url = image_url;
this.opis = opis;
}
public String getName() {
return name;
}
public String getImage_url() {
return image_url;
}
public String getOpis() {
return opis;
}
}

Zabytki.java(碎片(

package zabytki;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.android.volley.Request;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.ArrayList;
import eu.aisen.kamil.miejskiprzewodnik.AdapterZabytki;
import eu.aisen.kamil.miejskiprzewodnik.R;
import eu.aisen.kamil.miejskiprzewodnik.Zabytek;
public class Zabytki extends Fragment {
private static final String HI = "https://wydzialedukacji.rzeszow.pl/testowy.json";
private ArrayList<Zabytek>list_data;
private AdapterZabytki mSensorAdapter;
private RecyclerView mRyclerView;
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
@Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.zabytki_fragment, container, false);
mRyclerView = view.findViewById(R.id.main_list);
mRyclerView.setHasFixedSize(true);
mRyclerView.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));
list_data = new ArrayList<>();
getData();
mSensorAdapter = new AdapterZabytki(list_data, this);
mRyclerView.setAdapter(mSensorAdapter);
mSensorAdapter.notifyDataSetChanged();
return view;
}
private void getData() {
JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, HI, null,
new Response.Listener<JSONObject>() {
@Override
public void onResponse(JSONObject response) {
try {
JSONArray jsonArray = response.getJSONArray("results");
for(int i=0; i < jsonArray.length(); i++){
JSONObject object = jsonArray.getJSONObject(i);
String name = object.getString("name");
String image_url = object.getString("image_url");
String opis = object.getString("opis");
list_data.add(new Zabytek(name, image_url, opis));
}

} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
});
Volley.newRequestQueue(getActivity()).add(request);
}

}

zabytki_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.RecyclerView android:id="@+id/main_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
</android.support.v7.widget.RecyclerView>

obiectcard.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:card_view="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="200dp"
android:id="@+id/card_view"
android:layout_margin="5dp"
card_view:cardCornerRadius="4dp">
<android.support.constraint.ConstraintLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="16dp">
<ImageView
android:id="@+id/info_image"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginBottom="24dp"
android:layout_weight="1.0"
android:scaleType="centerCrop"
card_view:layout_constraintBottom_toBottomOf="parent"
card_view:srcCompat="@android:drawable/sym_def_app_icon"
tools:ignore="MissingConstraints" />
<TextView
android:id="@+id/info_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:layout_marginEnd="16dp"
android:text="tytułzabytku"
card_view:layout_constraintEnd_toEndOf="parent"
card_view:layout_constraintTop_toBottomOf="@+id/info_image" />
</android.support.constraint.ConstraintLayout>
</android.support.v7.widget.CardView>

Answer 1

我对您的代码有两个顾虑：1.在onResponse中，将所有项目添加到list_data后，必须在RecyclerView适配器(AdapterZabytki(上调用notifyDatasetChanged2.此外，ViewHolder中的info_image似乎没有高度，因为它没有顶部对齐和layout_height="0dp"

Answer 2

我仍然想知道如何将这些数据传输到ZabytkDetailActivity.class

我有这个：

mSensorAdapter.setListener(new AdapterZabytki.Listener() {
public void onClick(int position) {
ArrayList<Zabytek> object = new ArrayList<Zabytek>();
Intent intent = new Intent(getActivity(), ZabytekDetailActivity.class);
}
});

现在的问题是如何附加list_data中的结果，以便它们可以显示在MonumentDetailActivity.class 中