Java RecyclerView不显示来自JSON的数据
我试图在一个RecyclerView中显示从AirVisualAPI提供的JSON收集的数据。但是,我遇到了一个问题,JSON中的数据不会显示在RecyclerView中,而如果我自己(通过ArrayList)向其中添加数据,数据会显示在RecyclerView中 下面是我从API解析的JSON数据:Java RecyclerView不显示来自JSON的数据,java,android,json,android-recyclerview,android-volley,Java,Android,Json,Android Recyclerview,Android Volley,我试图在一个RecyclerView中显示从AirVisualAPI提供的JSON收集的数据。但是,我遇到了一个问题,JSON中的数据不会显示在RecyclerView中,而如果我自己(通过ArrayList)向其中添加数据,数据会显示在RecyclerView中 下面是我从API解析的JSON数据: { "status": "success", "data": { "city": "New York", "state": "New York", "country
{
"status": "success",
"data": {
"city": "New York",
"state": "New York",
"country": "USA",
"location": {
"type": "Point",
"coordinates": [
-73.928596,
40.694401
]
},
"current": {
"weather": {
"ts": "2018-09-12T23:00:00.000Z",
"hu": 93,
"ic": "10d",
"pr": 1024,
"tp": 23,
"wd": 102,
"ws": 2.31
},
"pollution": {
"ts": "2018-09-12T22:00:00.000Z",
"aqius": 18,
"mainus": "p2",
"aqicn": 6,
"maincn": "p2"
}
}
}
}
我怀疑的是,JSON中的数据根本没有添加到ArrayList中,因为记录ArrayList的大小会返回2
,这是我手动添加到列表中的两个对象
对于存储JSON数据的Station类,我使用jsonschema2pojo.org为Gson反序列化生成必要的类(不确定这是否是使用JSON数据的正确/最佳方式)
下面是MainActivity.java
public类MainActivity扩展了AppCompatActivity{
私有静态最终字符串url=”http://api.airvisual.com/v2/city?city=New%20York&state=New%20York&country=USA&key={{API_KEY}}”;
私人回收站;
专用适配器;
私有列表统计列表;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RecyclerView RecyclerView=(RecyclerView)findViewById(R.id.RecyclerView);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(新的LinearLayoutManager(本));
stationList=新的ArrayList();
loadRecycleServiceWdata();
//这些对象的信息在代码中
//但我决定不把它包括在这里
//因为这些只是测试用的
车站1=新车站();
车站2=新车站();
stationList.add(station1);
stationList.add(station2);
适配器=新适配器(此,stationList);
recyclerView.setAdapter(适配器);
//在控制台中返回2
Log.d(“列表大小”,“stationList.Size());
下面是loadRecycleServiceWdata
函数:
private void loadRecyclerViewData() {
RequestQueue requestQueue = Volley.newRequestQueue(this);
// Request a string response from the provided URL.
StringRequest stringRequest = new StringRequest(Request.Method.GET, url,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
// Using Gson to turn JSON to Java object of Station
GsonBuilder gsonBuilder = new GsonBuilder();
Gson gson = gsonBuilder.create();
Station station = gson.fromJson(response, Station.class);
stationList.add(station);
Log.d("API RESPONSE", response);
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.d("VOLLEY ERROR", error.toString());
}
});
// Add the request to the RequestQueue.
requestQueue.add(stringRequest);
}
private void loadRecycleServiceWdata(){
RequestQueue RequestQueue=Volley.newRequestQueue(this);
//从提供的URL请求字符串响应。
StringRequest StringRequest=新的StringRequest(Request.Method.GET,url,
新的Response.Listener(){
@凌驾
公共void onResponse(字符串响应){
//使用Gson将JSON转换为Station的Java对象
GsonBuilder GsonBuilder=新的GsonBuilder();
Gson-Gson=gsonBuilder.create();
Station=gson.fromJson(响应,Station.class);
stationList.add(车站);
Log.d(“API响应”,响应);
}
},new Response.ErrorListener(){
@凌驾
公共无效onErrorResponse(截击错误){
Log.d(“截击错误”,ERROR.toString());
}
});
//将请求添加到RequestQueue。
添加(stringRequest);
}
适配器类
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
private Context context;
private List<Station> stationList;
public Adapter(Context context, List<Station> stationList) {
this.context = context;
this.stationList = stationList;
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
View view = layoutInflater.inflate(R.layout.layout_listitem, null);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Station station = stationList.get(position);
holder.textViewTitle.setText(station.getData().getCity());
List<Double> coordinates = station.getData().getLocation().getCoordinates();
String listString = coordinates.stream().map(Object::toString)
.collect(Collectors.joining(", "));
holder.textViewShortDesc.setText(listString);
int aqius = station.getData().getCurrent().getPollution().getAqius();
holder.textViewRating.setText(aqius + "");
holder.textViewPrice.setText(rankAQIUS(aqius));
// holder.imageView.setImageDrawable(context.getResources().getDrawable());
}
public String rankAQIUS(int aqius) {
if (aqius >= 0 && aqius <= 50) {
return "Good";
} else if (aqius >= 51 && aqius <= 100) {
return "Moderate";
} else if (aqius >= 101 && aqius <= 150) {
return "Unhealthy for Sensitive Groups";
} else if (aqius >= 151 && aqius <= 200) {
return "Unhealthy";
} else if (aqius >= 201 && aqius <= 300) {
return "Very Unhealthy";
} else if (aqius >= 301) {
return "Hazardous";
}
return "ERROR";
}
@Override
public int getItemCount() {
return stationList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
ImageView imageView;
TextView textViewTitle, textViewShortDesc, textViewRating, textViewPrice;
public ViewHolder(View itemView) {
super(itemView);
imageView = itemView.findViewById(R.id.imageView);
textViewTitle = itemView.findViewById(R.id.textViewTitle);
textViewShortDesc = itemView.findViewById(R.id.textViewShortDesc);
textViewRating = itemView.findViewById(R.id.textViewRating);
textViewPrice = itemView.findViewById(R.id.textViewPrice);
}
}
}
公共类适配器扩展了RecyclerView.Adapter私有void loadRecyclerViewData(){RequestQueue RequestQueue=Volley.newRequestQueue(this);//从提供的URL请求字符串响应。StringRequest StringRequest=new StringRequest(Request.Method.GET,URL,new response.Listener(){@Override public void onResponse(字符串响应){//使用Gson将JSON转换为Station GsonBuilder的Java对象GsonBuilder=new GsonBuilder();Gson Gson=GsonBuilder.create();Station Station=Gson.fromJson(响应,Station.class);stationList.add(Station);
adapter.notifyDataSetChanged();
Log.d(“API响应”,响应);}},new RESPONSE.ErrorListener(){@Override public void onErrorResponse(VolleyError error){Log.d(“VOLLEY error,error.toString());}});//将请求添加到RequestQueue.RequestQueue.Add(stringRequest);}
向数据集中添加数据后,必须调用notifyDataSetChanged()。private void LoadRecycleServiceWdata(){RequestQueue RequestQueue=Volley.newRequestQueue(this);//从提供的URL请求字符串响应。StringRequest StringRequest=new StringRequest(Request.Method.GET,URL,new response.Listener()){@Override public void onResponse(String response){//使用Gson将JSON转换为Station GsonBuilder的Java对象GsonBuilder=new GsonBuilder();Gson Gson=GsonBuilder.create();Station Station=Gson.fromJson(response,Station.class);stationList.add(Station);
adapter.notifyDataSetChanged();
Log.d(“API响应”,响应);}},new RESPONSE.ErrorListener(){@Override public void onErrorResponse(VolleyError error){Log.d(“VOLLEY error,error.toString());}});//将请求添加到RequestQueue.RequestQueue.Add(stringRequest);}
在向数据集中添加数据后,必须调用notifyDataSetChanged()。啊,谢谢!我没有想到调用该方法,它正在工作。啊,谢谢!我没有想到调用该方法,它正在工作。
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="5dp">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="8dp">
<ImageView
android:id="@+id/imageView"
android:layout_width="120dp"
android:layout_height="90dp"
android:padding="4dp" />
<TextView
android:id="@+id/textViewTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:layout_toRightOf="@id/imageView"
android:text="City, State, Country"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Small"
android:textColor="#000000" />
<TextView
android:id="@+id/textViewShortDesc"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewTitle"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/imageView"
android:text="Longitude, Latitude"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Small" />
<TextView
android:id="@+id/textViewRating"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewShortDesc"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/imageView"
android:background="@color/colorPrimary"
android:paddingLeft="15dp"
android:paddingRight="15dp"
android:text="AQI"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Small.Inverse"
android:textStyle="bold" />
<TextView
android:id="@+id/textViewPrice"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/textViewRating"
android:layout_marginLeft="5dp"
android:layout_marginTop="5dp"
android:layout_toRightOf="@id/imageView"
android:text="Risk Level"
android:textAppearance="@style/Base.TextAppearance.AppCompat.Large"
android:textStyle="bold" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</LinearLayout>
private void loadRecyclerViewData() { RequestQueue requestQueue = Volley.newRequestQueue(this); // Request a string response from the provided URL. StringRequest stringRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() { @Override public void onResponse(String response) { // Using Gson to turn JSON to Java object of Station GsonBuilder gsonBuilder = new GsonBuilder(); Gson gson = gsonBuilder.create(); Station station = gson.fromJson(response, Station.class); stationList.add(station);
adapter.notifyDataSetChanged();
Log.d("API RESPONSE", response); } }, new Response.ErrorListener() { @Override public void onErrorResponse(VolleyError error) { Log.d("VOLLEY ERROR", error.toString()); } }); // Add the request to the RequestQueue. requestQueue.add(stringRequest); }