CardView 未呈现或数据未显示在 Recyclerview 中

Question

可能听起来像是一个重复的问题，但已经检查了发布的与 getItemCount() 未设置或布局 height/width 问题相关的问题。

我正在使用 CardView 作为 RecyclerView 项目。适配器获取 60 条记录（检查计数）但 CardView 甚至都没有显示数据。使用我还是新手的 ConstraintLayout ，它完美地显示了设计视图。数据是从外部 API 填充的，并使用运行良好的改造库。

Activity xml.

<android.support.constraint.ConstraintLayout 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"
    android:scrollbars="vertical"
    tools:context="com.techn.rails.Activity.TrainStatus">
/>

    <android.support.v7.widget.CardView
        android:id="@+id/search_cardView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:cardElevation="5dp">


        <android.support.constraint.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_margin="15dp">

        <android.support.v7.widget.AppCompatTextView
        android:id="@+id/trainno_search_tv"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:text="Train Number"
        app:layout_constraintEnd_toStartOf="@+id/trainno_search_et"
        app:layout_constraintHorizontal_chainStyle="spread_inside"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintHorizontal_weight="1"
             />

        <android.support.v7.widget.AppCompatEditText
        android:id="@+id/trainno_search_et"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintStart_toEndOf="@id/trainno_search_tv"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintBaseline_toBaselineOf="@+id/trainno_search_tv"
        android:inputType="number"
        android:maxLength="6"
        android:hint="@string/train_number"
        app:layout_constraintHorizontal_weight="1.5"
             />

            <android.support.v7.widget.AppCompatEditText
                android:id="@+id/doj_et"
                android:layout_width="0dp"
                app:layout_constraintEnd_toEndOf="@id/trainno_search_tv"
                android:layout_height="wrap_content"
                app:layout_constraintTop_toBottomOf="@+id/trainno_search_tv"
                app:layout_constraintLeft_toLeftOf="parent"
                android:layout_marginTop="12dp"
                />

            <android.support.v7.widget.AppCompatButton
                android:id="@+id/doj_btn"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                app:layout_constraintLeft_toRightOf="@+id/doj_et"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/trainno_search_et"
                app:layout_constraintBaseline_toBaselineOf="@+id/doj_et"
                android:layout_marginTop="12dp"
                android:text="@string/select_date"
                />

            <android.support.v7.widget.AppCompatButton
                android:id="@+id/submit"
                android:layout_width="100dp"
                android:layout_height="wrap_content"
                app:layout_constraintTop_toBottomOf="@+id/doj_btn"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                android:text="@string/submit_btn"
                />
        </android.support.constraint.ConstraintLayout>



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



    <android.support.v7.widget.RecyclerView
        android:id="@+id/train_list"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/result_cardview"
        app:layout_constraintBottom_toBottomOf="parent"
        android:scrollbars="vertical"
        android:padding="10dp"
        android:layout_margin="10dp"></android.support.v7.widget.RecyclerView>
</android.support.constraint.ConstraintLayout>

卡片视图xml

<android.support.constraint.ConstraintLayout
    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">

    <android.support.v7.widget.CardView
        android:id="@+id/train_status_card_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:layout_gravity="center"
        android:layout_margin="5dp"
        android:elevation="5dp"
        app:cardCornerRadius="5dp"
        android:background="?android:attr/selectableItemBackground">

        <android.support.constraint.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            >
            <android.support.v7.widget.AppCompatTextView
             android:id="@+id/train_stn_code_lbl"
             android:layout_height="wrap_content"
             android:layout_width="0dp"
             app:layout_constraintTop_toTopOf="parent"
             app:layout_constraintLeft_toLeftOf="parent"
/>
            <android.support.v7.widget.AppCompatTextView
                android:id="@+id/train_stn_code"
                android:layout_height="wrap_content"
                android:layout_width="0dp"
                app:layout_constraintTop_toTopOf="parent"
                app:layout_constraintLeft_toRightOf="@id/train_stn_code_lbl"
                app:layout_constraintRight_toRightOf="parent" />
            <android.support.v7.widget.AppCompatTextView
                android:id="@+id/train_sch_arr_lbl"
                android:layout_height="wrap_content"
                android:layout_width="0dp"
                app:layout_constraintTop_toBottomOf="@id/train_stn_code_lbl"
                app:layout_constraintLeft_toLeftOf="parent"
                 />

            <android.support.v7.widget.AppCompatTextView
                android:id="@+id/train_sch_arr"
                android:layout_height="wrap_content"
                android:layout_width="0dp"
                app:layout_constraintTop_toBottomOf="@id/train_stn_code"
                app:layout_constraintLeft_toRightOf="@id/train_sch_arr_lbl"
                app:layout_constraintRight_toRightOf="parent" />
            <android.support.v7.widget.AppCompatTextView
                android:id="@+id/train_act_dep_lbl"
                android:layout_height="wrap_content"
                android:layout_width="0dp"
                app:layout_constraintTop_toBottomOf="@id/train_sch_arr_lbl"
                app:layout_constraintLeft_toLeftOf="parent"
                />

            <android.support.v7.widget.AppCompatTextView
                android:id="@+id/train_act_dep"
                android:layout_height="wrap_content"
                android:layout_width="0dp"
                app:layout_constraintTop_toBottomOf="@id/train_sch_arr_lbl"
                app:layout_constraintLeft_toRightOf="@id/train_act_dep_lbl"
                app:layout_constraintRight_toRightOf="parent" />

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

Activity

public class TrainStatus extends AppCompatActivity implements DatePickerDialog.OnDateSetListener {

    @BindView(R.id.doj_btn)
    AppCompatButton mDojBtn;
    @BindView(R.id.trainno_search_et)
    AppCompatEditText mTrainNumber;
    @BindView(R.id.submit)
    AppCompatButton mSubmit;
    @BindView(R.id.train_list)
    RecyclerView recyclerView;

    private Calendar calendar;
    private DatePickerDialog datePickerDialog;
    int Year, Month, Day ;
    String dateSelected, dateToDisplay;
    private TrainStatusRoute mAdapter;
    private List<Route> mRoutes;
    private static final String TAG = TrainStatus.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_train_status);
        ButterKnife.bind(this);

        mRoutes = new ArrayList<>();
        mAdapter = new TrainStatusRoute(this,mRoutes);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(mAdapter);

        calendar = Calendar.getInstance();

        Year = calendar.get(Calendar.YEAR) ;
        Month = calendar.get(Calendar.MONTH);
        Day = calendar.get(Calendar.DAY_OF_MONTH);

        mDojBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                datePickerDialog = DatePickerDialog.newInstance(TrainStatus.this, Year, Month, Day);
                datePickerDialog.setThemeDark(false);
                datePickerDialog.showYearPickerFirst(false);
            }
        });

        mSubmit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
requestAPIQuery(mTrainNumber.getText().toString(),dateSelected);
            }
        });


    }

    @Override
    public void onDateSet(DatePickerDialog view, int Year, int Month, int Day) {
        dateSelected = String.valueOf(Year)+String.valueOf(Month + 1)+String.valueOf(Day);

    }

    private void requestAPIQuery (String trainNumber, String doj){

        IApi apiService = APIClient.getClient().create(IApi.class);

        Call<TrainStatus> call = apiService.getTrainStatus(trainNumber,doj,API_KEY);

        call.enqueue(new Callback<TrainStatus>() {
            @Override
            public void onResponse(Call<TrainStatus> call, Response<TrainStatus> response) {
                List<Route> trainStatuses = response.body().getRoute();
                mAdapter.notifyDataSetChanged();
                Log.d(TAG,"Number of trains"+trainStatuses.size());//getting count 60 here
            }

            @Override
            public void onFailure(Call<com.technovibe.railstat.Model.TrainStatus> call, Throwable t) {

                Log.e(TAG, t.toString());
            }
        });

    }

}

适配器代码

public class TrainStatusRoute extends RecyclerView.Adapter<TrainStatusRoute.RouteViewHolder> {

    private Context mContext;
    private List<Route> mRoutes;

    public static class RouteViewHolder extends RecyclerView.ViewHolder{

        @BindView(R.id.train_act_arr)
        TextView mActArr;
        @BindView(R.id.train_act_dep)
        TextView mActDep;
        @BindView(R.id.train_sch_arr)
        TextView mSchArr;
        @BindView(R.id.train_sch_dep)
        TextView mSchDep;

        public RouteViewHolder(View itemView) {
            super(itemView);
            ButterKnife.bind(this, itemView);
        }
    }

    public TrainStatusRoute(Context context, List<Route> routeList) {
        this.mContext = context;
        this.mRoutes = routeList;
    }

    @Override
    public TrainStatusRoute.RouteViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.train_status_card, parent, false);

        return new RouteViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(TrainStatusRoute.RouteViewHolder holder, int position) {
        Route route = mRoutes.get(position);
        holder.mActArr.setText(route.getActarr());
        holder.mActDep.setText(route.getActdep());
        holder.mSchDep.setText(route.getSchdep());
        holder.mSchArr.setText(route.getScharr());

    }

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

请耐心等待我发布冗长的代码。

感谢任何帮助，提前致谢。

Answer 1

我想问题可能出在卡片视图的宽度和高度上：

<android.support.v7.widget.CardView
        android:id="@+id/search_cardView"
        android:layout_width="0dp"
        android:layout_height="wrap_content"

尝试更改宽度和高度值，假设宽度 match_parent 和高度为 60 dp，看看项目是否会出现。

Answer 2

 public void onResponse(Call<TrainStatus> call, Response<TrainStatus> response) {
                List<Route> trainStatuses = response.body().getRoute();
                //Add this line here
                mAdapter.setRoutes(trainStatuses);
                mAdapter.notifyDataSetChanged();
                Log.d(TAG,"Number of trains"+trainStatuses.size());//getting count 60 here
            }

并在适配器中为您的列表定义一个 setter

public void setRoutes(List<Route> routes){
    mRoutes = routes;
}

CardView 未呈现或数据未显示在 Recyclerview 中

CardView not rendered or data is not showing up in Recyclerview

android

android-adapter

android-cardview

android-recyclerview