Fragment内RecyclerView无法渲染，模拟器显示空白屏求助

我尝试在Fragment里展示带少量数据的RecyclerView，但始终显示空白屏幕。PreferenceMenuFragment通过XML嵌套在SettingsFragment布局中，页面层级如下：

NewDemoActivity(父Activity)
    SettingsFragment(NewDemoActivity的子Fragment) 

                   1. PreferenceMenuFragment
                   2. DetailsFragment

相关代码实现 #

SettingsFragment #

public class SettingFragment extends Fragment implements IMqttListener, 
IPropertyChangeListener, ViewVisibilityChangeListener {

private NewDemoActivity mActivity;

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mActivity = (NewDemoActivity) requireActivity();
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    return inflater.inflate(R.layout.settings_layout, container, false);
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
}

settings_layout.xml #

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:background="@color/black">

<androidx.fragment.app.FragmentContainerView
    android:id="@+id/pref_fragment_container_view"
    android:name="com.xx.xx.xx.xx.PreferenceMenuFragment"
    android:layout_width="318dp"
    android:layout_height="500dp"
    android:layout_marginStart="46dp"
    android:layout_marginEnd="79dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toStartOf="@+id/details_fragment_container_view"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintStart_toStartOf="parent"
    android:background="@color/white"
    app:layout_constraintTop_toTopOf="@+id/details_fragment_container_view"
    app:layout_constraintVertical_bias="0.0" />

<androidx.fragment.app.FragmentContainerView
    android:id="@+id/details_fragment_container_view"
    android:layout_width="540dp"
    android:layout_height="597dp"
    android:layout_marginTop="95dp"
    android:layout_marginEnd="41dp"
    android:layout_marginBottom="76dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toEndOf="@+id/pref_fragment_container_view"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.0" />

</androidx.constraintlayout.widget.ConstraintLayout>

PreferenceMenuFragment #

public class PreferenceMenuFragment extends Fragment {

private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";

private String mParam1;
private String mParam2;

private NewDemoActivity mActivity;
private List<String> menu_titles;
private int[] menu_icons=new int[]{R.drawable.brightness_icon_blue,R.drawable.bluetooth_icon_blue,R.drawable.camera_icon_blue,R.drawable.seat_alignment_icon_blue,R.drawable.notification_icon_blue,R.drawable.display_theme_icon_blue
        ,R.drawable.language_icon_blue,R.drawable.about_icon_blue};
private int[] selected_menu_icons=new int[]{R.drawable.brightness_icon_white,R.drawable.bluetooth_icon_white,R.drawable.camera_icon_white,R.drawable.seat_alignment_icon_white,R.drawable.notification_icon_white,R.drawable.display_theme_icon_white,
        R.drawable.language_icon_white,R.drawable.about_icon_white};

public PreferenceMenuFragment() {
}

public static PreferenceMenuFragment newInstance(String param1, String param2) {
    PreferenceMenuFragment fragment = new PreferenceMenuFragment();
    Bundle args = new Bundle();
    args.putString(ARG_PARAM1, param1);
    args.putString(ARG_PARAM2, param2);
    fragment.setArguments(args);
    return fragment;
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (getArguments() != null) {
        mParam1 = getArguments().getString(ARG_PARAM1);
        mParam2 = getArguments().getString(ARG_PARAM2);
    }
    menu_titles = Arrays.asList(getResources().getStringArray(R.array.setting_option_title));
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_preference, container, false);
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    RecyclerView recyclerView = view.findViewById(R.id.setting_menu_recycler_view);
    recyclerView.addItemDecoration(new DividerItemDecoration(getContext(),LinearLayoutManager.VERTICAL));
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
    SettingsMenuAdapter menuAdapter=new SettingsMenuAdapter(getContext(),menu_titles,menu_icons,selected_menu_icons);
    recyclerView.setAdapter(menuAdapter);
}

fragment_preference.xml #

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:background="@color/black">

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/setting_menu_recycler_view"
    android:layout_width="280dp"
    android:layout_height="500dp"
    android:layout_marginStart="25dp"
    android:layout_marginTop="50dp"
    android:layout_marginEnd="719dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.046"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.369" />

</androidx.constraintlayout.widget.ConstraintLayout>

SettingsMenuAdapter #

public class SettingsMenuAdapter extends RecyclerView.Adapter<SettingsMenuViewHolder> 
{

Context context;
List<String> label;
int[] icons;
int[] selectedMenuIcons;
int selectedPosition;

public SettingsMenuAdapter(Context context, List<String> label, int[] icons, int[] selectedIcons) {
    this.context = context;
    this.label = label;
    this.icons = icons;
    this.selectedMenuIcons = selectedIcons;
}

@NonNull
@Override
public SettingsMenuViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    return new SettingsMenuViewHolder(LayoutInflater.from(context).inflate(R.layout.settings_item_layout,parent,false));
}

@Override
public void onBindViewHolder(@NonNull SettingsMenuViewHolder holder, int position) {
    holder.textView.setText(label.get(position));
    if(position==selectedPosition){
        holder.parentItemLayout.setBackground(context.getDrawable(R.drawable.shape_rounded_corner));
        holder.textView.setTextColor(context.getResources().getColor(R.color.white,context.getTheme()));
        holder.imageView.setImageDrawable(context.getResources().getDrawable(selectedMenuIcons[holder.getBindingAdapterPosition()],context.getTheme()));

    }else{
        holder.parentItemLayout.setBackground(null);
        holder.textView.setTextColor(context.getResources().getColor(R.color.seekbar_blue,context.getTheme()));
        holder.imageView.setImageDrawable(context.getResources().getDrawable(icons[holder.getBindingAdapterPosition()],context.getTheme()));
    }

    holder.parentItemLayout.setOnClickListener(v -> {
        selectedPosition=holder.getBindingAdapterPosition();
    });
}

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

settings_item_layout.xml #

<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/setting_item_parent_layout"
android:layout_width="match_parent"
android:layout_height="45dp"
android:orientation="horizontal"
android:layout_gravity="center"
android:gravity="center"
android:clickable="true">

<ImageView
    android:id="@+id/settingsItemImage"
    android:layout_width="0dp"
    android:layout_weight="1"
    android:layout_height="wrap_content" />

<TextView
    android:id="@+id/settingsItemLabel"
    android:layout_width="0dp"
    android:layout_weight="5"
    android:layout_height="wrap_content"
    android:layout_marginStart="5dp"
    android:textColor="@color/white"/>

</androidx.appcompat.widget.LinearLayoutCompat>

问题排查与修复方案 #

1. 修复RecyclerView布局约束 #

fragment_preference.xml中RecyclerView的android:layout_marginEnd="719dp"值过大，直接导致RecyclerView被挤压到屏幕外不可见。修改为合理值或移除该属性：

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/setting_menu_recycler_view"
    android:layout_width="280dp"
    android:layout_height="500dp"
    android:layout_marginStart="25dp"
    android:layout_marginTop="50dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.0"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent" />

2. 确保数据正确加载 #

检查res/values/strings.xml中setting_option_title数组是否存在且有内容：

<string-array name="setting_option_title">
    <item>亮度调节</item>
    <item>蓝牙设置</item>
    <item>相机配置</item>
    <item>座椅调整</item>
    <item>通知管理</item>
    <item>显示主题</item>
    <item>语言设置</item>
    <item>关于我们</item>
</string-array>

3. 补全ViewHolder控件绑定 #

确保SettingsMenuViewHolder正确初始化布局中的控件：

public class SettingsMenuViewHolder extends RecyclerView.ViewHolder {
    TextView textView;
    ImageView imageView;
    LinearLayoutCompat parentItemLayout;

    public SettingsMenuViewHolder(@NonNull View itemView) {
        super(itemView);
        textView = itemView.findViewById(R.id.settingsItemLabel);
        imageView = itemView.findViewById(R.id.settingsItemImage);
        parentItemLayout = itemView.findViewById(R.id.setting_item_parent_layout);
    }
}

4. 修复点击事件UI刷新 #

点击列表项后更新selectedPosition但未触发刷新，导致选中状态不生效，修改Adapter点击事件：

holder.parentItemLayout.setOnClickListener(v -> {
    int oldPosition = selectedPosition;
    selectedPosition = holder.getBindingAdapterPosition();
    notifyItemChanged(oldPosition);
    notifyItemChanged(selectedPosition);
});

5. 排查颜色对比度问题 #

PreferenceMenuFragment背景为黑色，未选中状态文字颜色为seekbar_blue，若颜色过暗会看起来像空白。可临时修改未选中状态文字颜色为白色测试：

holder.textView.setTextColor(context.getResources().getColor(R.color.white, context.getTheme()));

内容的提问来源于stack exchange，提问作者Satyasarathi