我如何显示从API获取的列表？

Question

我在我的应用程序上有一个页面，我正在尝试显示cars的列表，但我不确定问题是否出在我的列表代码或提取代码上，因此请尽可能多地添加代码。

这里是我要显示数据的RelativeLayout：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".CarList">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/main_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</RelativeLayout>

这是我希望通过获取的数据显示我的代码的方式：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/cars_List_items"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">



        <TextView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:drawableStart="@drawable/ic_cars"
            android:drawableLeft="@drawable/ic_cars"
            android:drawablePadding="5dp"
            android:gravity="start"
            android:paddingLeft="16dp"
            android:paddingRight="16dp"
            android:text="Cars Sale"
            android:textSize="12sp" />

        <TextView
            android:id="@+id/carDetailsDate"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:drawableEnd="@drawable/ic_history"
            android:drawableRight="@drawable/ic_history"
            android:drawablePadding="5dp"
            android:gravity="end"
            android:maxLength="10"
            android:maxLines="1"
            android:paddingLeft="16dp"
            android:paddingRight="16dp"
            android:textColor="@color/colorPrimary"
            android:textSize="12sp"
            tools:text="20/10/1999" />



    <ImageView
        android:id="@+id/carDetailsImage"
        android:layout_width="145dp"
        android:layout_height="145dp"
        android:scaleType="fitXY"
        app:layout_constraintDimensionRatio="4:1"
        app:layout_constraintStart_toStartOf="parent"
        app:srcCompat="@drawable/car1" />

    <TextView
        android:id="@+id/carDetailsTitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginLeft="16dp"
        android:layout_marginTop="24dp"
        android:textSize="18sp"
        app:layout_constraintStart_toEndOf="@+id/carDetailsImage"
        app:layout_constraintTop_toTopOf="@+id/carDetailsImage"
        tools:text="Car1" />

    <TextView
        android:id="@+id/carDetailsCategory"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="8dp"
        android:textSize="18sp"
        android:textStyle="bold"
        app:layout_constraintStart_toStartOf="@+id/carDetailsTitle"
        app:layout_constraintTop_toBottomOf="@+id/carDetailsTitle"
        tools:text="V1 208" />

    <TextView
        android:id="@+id/carDetailsPrice"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAllCaps="true"
        android:textColor="@color/homepage_car"
        android:textSize="18sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="@+id/carDetailsCategory"
        app:layout_constraintEnd_toEndOf="@+id/carDetailsYear"
        app:layout_constraintHorizontal_bias="0.93"
        app:layout_constraintStart_toEndOf="@+id/carDetailsCategory"
        app:layout_constraintTop_toTopOf="@+id/carDetailsCategory"
        tools:text="20000" />

    <TextView
        android:id="@+id/carDetailsDistance"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        android:drawableTop="@drawable/ic_km"
        android:gravity="bottom"
        android:paddingTop="22dp"
        android:textSize="14sp"
        app:drawableTint="@color/homepage_car"
        app:layout_constraintBottom_toBottomOf="@+id/carDetailsImage"
        app:layout_constraintEnd_toStartOf="@+id/cardetailsGear"
        app:layout_constraintStart_toEndOf="@+id/carDetailsImage"
        app:layout_constraintTop_toBottomOf="@+id/carDetailsCategory"
        tools:text="2000" />

    <TextView
        android:id="@+id/cardetailsGear"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:drawableTop="@drawable/ic_motion_vector"
        android:gravity="bottom"
        android:paddingTop="22dp"
        android:textSize="14sp"
        app:drawableTint="@color/homepage_car"
        app:layout_constraintBottom_toBottomOf="@+id/carDetailsDistance"
        app:layout_constraintEnd_toStartOf="@+id/carDetailsOil"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/carDetailsDistance"
        app:layout_constraintTop_toTopOf="@+id/carDetailsDistance"
        tools:text="Automatic" />

    <TextView
        android:id="@+id/carDetailsOil"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:drawableTop="@drawable/ic_fuel_type"
        android:gravity="bottom"
        android:paddingTop="22dp"
        android:textSize="14sp"
        app:drawableTint="@color/homepage_car"
        app:layout_constraintBottom_toBottomOf="@+id/cardetailsGear"
        app:layout_constraintEnd_toStartOf="@+id/carDetailsYear"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/cardetailsGear"
        app:layout_constraintTop_toTopOf="@+id/cardetailsGear"
        tools:text="Diesel" />

    <TextView
        android:id="@+id/carDetailsYear"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:drawableTop="@drawable/ic_general_model"
        android:gravity="bottom"
        android:paddingTop="22dp"
        android:textSize="14sp"
        app:drawableTint="@color/homepage_car"
        app:layout_constraintBottom_toBottomOf="@+id/carDetailsOil"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toEndOf="@+id/carDetailsOil"
        app:layout_constraintTop_toTopOf="@+id/carDetailsOil"
        tools:text="2010" />

    <TextView
        android:id="@+id/button"
        android:layout_width="0dp"
        android:layout_height="2dp"
        android:background="@color/colorPrimary"
        android:textSize="10sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/carDetailsImage" />

</LinearLayout>

这是我的CarList类，其中读取数据代码为：

public class CarList extends AppCompatActivity {

    private RecyclerView mList;

    private LinearLayoutManager linearLayoutManager;
    private DividerItemDecoration dividerItemDecoration;
    private List<CarClass> carClassList;
    private RecyclerView.Adapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_car_list);

        mList = findViewById(R.id.main_list);

        carClassList = new ArrayList<>();
        adapter = new CarAdapter(getApplicationContext(), carClassList);

        linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL);
        dividerItemDecoration = new DividerItemDecoration(mList.getContext(), linearLayoutManager.getOrientation());

        mList.setHasFixedSize(true);
        mList.setLayoutManager(linearLayoutManager);
        mList.addItemDecoration(dividerItemDecoration);
        mList.setAdapter(adapter);

        getData();
    }



    private void getData() {
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(URL_CAR_LIST, null, new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        try {
                            JSONArray jsonArray = response.getJSONArray("listCar");

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

                                CarClass car = new CarClass();
                                car.setTitle(jsonObject.getString("adTitle"));
                                car.setDate(jsonObject.getString("adDate"));
                                car.setPrice(jsonObject.getDouble("adPrice"));
                                car.setCategory(jsonObject.getString("category"));
                                car.setKilometer(jsonObject.getDouble("kilometer"));
                                car.setModelYear(jsonObject.getString("modelYear"));
                                car.setFuel(jsonObject.getString("fuelType"));
                                car.setGear(jsonObject.getString("gearType"));

//                                carClassList.add(car);
                            }
                        } catch (JSONException ex) {
                            ex.printStackTrace();
                        }
                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                Log.e("Volley", error.toString());
            }
        });
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(jsonObjectRequest);
    }
}

这是我的CarClass：

public class CarClass {
    public String title;
    public String date;
    public Double price;
    public String category;
    public String brand;
    public String brandModel;
    public Double kilometer;
    public String modelYear;
    public String fuel;
    public String gear;

    public CarClass() {

    }

    public CarClass( String title, String date, Double price, String category,String brand, String brandModel, Double kilometer, String modelYear, String fuel, String gear) {
        this.title = title;
        this.date = date;
        this.price = price;
        this.category = category;
        this.brand = brand;
        this.brandModel = brandModel;
        this.kilometer = kilometer;
        this.modelYear = modelYear;
        this.fuel = fuel;
        this.gear = gear;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public Double getPrice() {
        return price;
    }

    public void setPrice(Double price) {
        this.price = price;
    }

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public String getBrandModel() {
        return brandModel;
    }

    public void setBrandModel(String brandModel) {
        this.brandModel = brandModel;
    }

    public Double getKilometer() {
        return kilometer;
    }

    public void setKilometer(Double kilometer) {
        this.kilometer = kilometer;
    }

    public String getModelYear() {
        return modelYear;
    }

    public void setModelYear(String modelYear) {
        this.modelYear = modelYear;
    }

    public String getFuel() {
        return fuel;
    }

    public void setFuel(String fuel) {
        this.fuel = fuel;
    }

    public String getGear() {
        return gear;
    }

    public void setGear(String gear) {
        this.gear = gear;
    }
}

这里是我的CarAdapter：

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

    private Context context;
    private List<CarClass>  list;

    public CarAdapter(Context context, List<CarClass> list) {
        this.context = context;
        this.list = list;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(context).inflate(R.layout.cars_list, parent, false);
        return new ViewHolder(v);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        CarClass car = list.get(position);

        holder.textDate.setText(car.getDate());
        holder.textTitle.setText(car.getTitle());
        holder.textCategory.setText(car.getCategory());
        holder.textPrice.setText(String.valueOf(car.getPrice()));
        holder.textKilometer.setText(String.valueOf(car.getKilometer()));
        holder.textGear.setText(car.getGear());
        holder.textFuel.setText(car.getFuel());
        holder.textYear.setText(car.getModelYear());
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        public TextView textDate, textTitle, textCategory, textPrice, textKilometer, textGear, textFuel, textYear;

        public ViewHolder(View itemView) {
            super(itemView);

            textDate = itemView.findViewById(R.id.carDetailsDate);
            textTitle = itemView.findViewById(R.id.carDetailsTitle);
            textCategory = itemView.findViewById(R.id.carDetailsCategory);
            textPrice = itemView.findViewById(R.id.carDetailsPrice);
            textKilometer = itemView.findViewById(R.id.carDetailsDistance);
            textGear = itemView.findViewById(R.id.cardetailsGear);
            textFuel = itemView.findViewById(R.id.carDetailsOil);
            textYear = itemView.findViewById(R.id.carDetailsYear);
        }
    }

}

我无法确定错误是由于我的代码引起的，还是fetch代码中缺少了什么？

最后但并非最不重要的一点是打开活动时调试器显示的内容：

D/Volley: [1453] BasicNetwork.logSlowRequests: HTTP response for request=<[ ] "#MyAPILInk" 0x5557fcc5 NORMAL 1> [lifetime=8506], [size=3841], [rc=200], [retryCount=1]

这是logcat显示的内容：

2020-02-07 09:04:35.285 28694-28793/com.example.wasit D/Volley: [1453] BasicNetwork.logSlowRequests: HTTP response for request=<[ ] "#MyAPILink" 0x5557fcc5 NORMAL 1> [lifetime=8506], [size=3841], [rc=200], [retryCount=1]

Answer 1

将这两行移动到getData方法

 adapter = new CarAdapter(getApplicationContext(), carClassList);
 mList.setAdapter(adapter);