JSON 解析数据不显示在 Fragment 中（使用 Volley）

Question

几个月前我开始学习 Android 开发，目前我正在学习使用 JSON 数据。

几天前，我尝试解析 JSON 数据并将其显示在 RecyclerView 中并且它有效（对于整个事情我遵循了几个 Youtube 教程），但现在我想在 Fragment 中做同样的事情并且它没有不行。

我有一个 MainActivity，它目前除了在 Fragments 中导航之外什么都不做。

应用程序正常工作（我可以导航），当我点击 SensorsFragment 按钮（带有 JSON 数据的按钮）时出现较深的灰色背景，但不是数据。

我试图找到问题所在，但我看不出问题出在哪里。

这是我要解析的数据：http://www.mocky.io/v2/5cd67f9d300000630060612b

物品类别

public class SensorItem {

    private String mID;
    private String mType;
    private int mValue;

    public SensorItem(String ID, String Type, int value ){
        mID=ID;
        mType=Type;
        mValue=value;
    }

    public String getID(){
        return mID;
    }

    public String getType(){
        return mType;
    }

    public int getValue(){
        return mValue;
    }
}

适配器

public class SensorAdapter extends RecyclerView.Adapter<SensorAdapter.SensorViewHolder> {

    private Context mContext;
    private ArrayList<SensorItem> mSensorList;
    private LayoutInflater inflater;

    public SensorAdapter(Context context, ArrayList<SensorItem> mSensorList){
        inflater = LayoutInflater.from(context);
        this.mContext=context;
        this.mSensorList=mSensorList;

    }

    @Override
    public SensorViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
        View v = inflater.inflate(R.layout.sensor_item, viewGroup, false);
        SensorViewHolder holder = new SensorViewHolder(v);
        return holder;
    }

    @Override
    public void onBindViewHolder(SensorViewHolder holder, int i) {
        SensorItem currentItem = mSensorList.get(i);

        String sensorID = currentItem.getID();
        String sensorType = currentItem.getType();
        int sensorValue = currentItem.getValue();

        holder.mTextViewID.setText(sensorID);
        holder.mTextViewType.setText(sensorType);
        holder.mTextViewValue.setText(sensorValue);
    }

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

    public void clearAdaptor() {
        mSensorList.clear();
    }

    public class SensorViewHolder extends RecyclerView.ViewHolder{

        public TextView mTextViewID;
        public TextView mTextViewType;
        public TextView mTextViewValue;

        public SensorViewHolder(View itemView) {
            super(itemView);
            mTextViewID = itemView.findViewById(R.id.text_view_id);
            mTextViewType = itemView.findViewById(R.id.text_view_type);
            mTextViewValue = itemView.findViewById(R.id.text_view_value);
        }
    }
}

和片段

public class SensorsFragment extends Fragment {

    private RecyclerView mRyclerView;
    private SensorAdapter mSensorAdapter;
    private ArrayList<SensorItem> mSensorList = new ArrayList<SensorItem>();
    private RequestQueue mRequestQueue;

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

        mRyclerView = view.findViewById(R.id.recycler_view);

        mSensorAdapter = new SensorAdapter(getContext(), mSensorList);
        mSensorAdapter.clearAdaptor();

        mRyclerView.setAdapter(mSensorAdapter);
        mRyclerView.setHasFixedSize(true);
        mRyclerView.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));

        mSensorList = new ArrayList<>();
        mRequestQueue = Volley.newRequestQueue(getActivity().getApplicationContext());

        parseJSON();
        return view;
    }

    private void parseJSON(){
        String url = "http://www.mocky.io/v2/5cd67f9d300000630060612b";

        JsonObjectRequest request = new JsonObjectRequest(Request.Method.GET, url, null,
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {
                        try {
                            JSONArray jsonArray = response.getJSONArray("C07-14");

                            for(int i=0; i < jsonArray.length(); i++){
                                JSONObject sensor = jsonArray.getJSONObject(i);

                                String ID = sensor.getString("id");
                                String type = sensor.getString("type");
                                int value = sensor.getInt("value");

                                mSensorList.add(new SensorItem(ID, type, value));
                            }

                            mSensorAdapter.notifyDataSetChanged();

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

                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                error.printStackTrace();
            }
        });

        mRequestQueue.add(request);
    }
}

还有，XML 文件：

fragment_sensors.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent" android:layout_height="match_parent"
    >

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/darker_gray"
        />

</RelativeLayout>

sensor_item.xml

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_margin="8dp"
    app:cardCornerRadius="8dp"
    >

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:padding="16dp"
        android:gravity="left"
       >

        <TextView
            android:id="@+id/text_view_id"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="ID"
            android:textColor="@android:color/black"
            android:textSize="20sp"/>

        <TextView
            android:id="@+id/text_view_type"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="TYPE"
            android:textColor="@android:color/black"
            android:textSize="20sp"
            android:layout_below="@+id/text_view_id"/>

    </RelativeLayout>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:padding="16dp"
        android:gravity="right"
        >

        <TextView
            android:id="@+id/text_view_value"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="VALUE"
            android:textColor="@android:color/black"
            android:textSize="20sp"/>

    </RelativeLayout>

</android.support.v7.widget.CardView>

Answer 1

我已经编辑了你的回复

    try {
        JSONObject jsonObject=new JSONObject(""+response);
        JSONArray jsonArray = jsonObject.getJSONArray("C07-14");

        for(int i=0; i < jsonArray.length(); i++){
            JSONObject sensor = jsonArray.getJSONObject(i);

            String ID = sensor.getString("id");
            String type = sensor.getString("type");
            int value = sensor.getInt("value");

            mSensorList.add(new SensorItem(ID, type, value));
        }

        mSensorAdapter.dataChanged(mSensorList);

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