这是我第一次尝试与 RecyclerView 进行数据绑定(bind)，但不是我第一次使用 RecyclerView 本身。

由于某种原因，没有调用任何适配器方法 - 甚至没有调用 getItemCount()。 这可能是我的 RecyclerView 的一个愚蠢问题，与数据绑定(bind)完全无关，但我看不出有什么问题。

       View rootview = inflater.inflate(R.layout.fragment_profile_first, container, false);
    // Initialize recycler view

    RecyclerView badgesRV = (RecyclerView) rootview.findViewById(R.id.badgesRV);
    LinearLayoutManager llm = new LinearLayoutManager(getActivity());
    llm.setOrientation(LinearLayoutManager.HORIZONTAL);
    badgesRV.setLayoutManager(llm);

    BadgeAdapter badgeAdapter = new BadgeAdapter(profileObject.badgesEntity.badges);
    badgesRV.setAdapter(badgeAdapter);

适配器:

    public class BadgeAdapter extends RecyclerView.Adapter<BadgeAdapter.BadgeBindingHolder>{

    private static final int MAX_BADGES_TO_DISPLAY = 5;
    private BadgeObject[] badges;

    public BadgeAdapter(BadgeObject[] badges){
        this.badges = badges;
    }

    @Override
    public BadgeBindingHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.profile_badge_row, parent, false);
        BadgeBindingHolder holder = new BadgeBindingHolder(v);
        return holder;
    }

    @Override
    public void onBindViewHolder(BadgeBindingHolder holder, int position) {
        final BadgeObject badgeObject = badges[position];
        holder.getBinding().setVariable(BR.badge, badgeObject);
        holder.getBinding().executePendingBindings();

    }

    @Override
    public int getItemCount() {
        Log.d(TAG, "item count = " + Math.min(MAX_BADGES_TO_DISPLAY, badges.length));
        return Math.min(MAX_BADGES_TO_DISPLAY, badges.length);
    }

    public class BadgeBindingHolder extends RecyclerView.ViewHolder{
        private ViewDataBinding binding;

        public BadgeBindingHolder(View rowView) {
            super(rowView);
            binding = DataBindingUtil.bind(rowView);
        }
        public ViewDataBinding getBinding() {
            return binding;
        }
    }
}

profile_badge_row.xml

<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">

<data>
    <variable name="badge" type="parseJsonEntities.requestObjects.BadgeObject"/>
</data>

<LinearLayout
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@{badge.badgeImage}"/>

</LinearLayout>

我查过了，那里肯定有数据。 我错过了什么？

======================

更新:

据我所知，RecyclerView 在数据绑定(bind)布局中根本不起作用。 我只用我的 RV 创建了一个单独的布局，它运行良好。 一旦我将它包含在我的主要布局中，它就停止工作了。

不确定这是错误还是功能。

所以，我想如果我把它做成一个自定义 View ，也许它会起作用，而且确实如此。 我的问题是我不知道如何将值传递到我的自定义 View 中。

我看了here但无法弄清楚他到底是什么意思。 这是我在自定义 View 中的代码。

    LayoutInflater inflater = (LayoutInflater)
            context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View view = inflater.inflate(R.layout.profile_badges_layout, this, true);
    ProfileBadgesLayoutBinding binding = ProfileBadgesLayoutBinding.inflate(inflater);

    RecyclerView badgesRV = (RecyclerView) view.findViewById(R.id.badgesRV);

    LinearLayoutManager llm = new LinearLayoutManager(context);
    llm.setOrientation(LinearLayoutManager.HORIZONTAL);
    badgesRV.setLayoutManager(llm);

    BadgeAdapter badgeAdapter = new BadgeAdapter(null);
    badgesRV.setAdapter(badgeAdapter);

这会给出一条消息，即找不到 ProfileBadgesLayoutBinding。

最佳答案

在您的 onCreateViewHolder 中:

@Override
public BadgeBindingHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    ProfileBadgeRowBinding binding = DataBindingUtil.inflate(inflater, R.layout.profile_badge_row, parent, false);
    BadgeBindingHolder holder = new BadgeBindingHolder(binding.getRoot(), binding);
    return holder;
}

并在您的项目 View 中添加绑定(bind)

public class BadgeBindingHolder extends RecyclerView.ViewHolder{
    private ProfileBadgeRowBinding binding;

    public BadgeBindingHolder(View rowView, ProfileBadgeRowBinding binding) {
        super(rowView);
        this.binding = binding;
    }

    ...

}

并在bindToViewHolder中设置变量

@Override
public void bindToViewHolder(RecyclerView.ViewHolder viewHolder) {
    ProfileBadgeRowBinding binding = ((BadgeBindingHolder) viewHolder).binding;
    binding.setVariable(BR.badge, badge);
    binding.executePendingBindings(); // This line is important, it will force to load the variable in a custom view
}

如果要访问 View ，请在 xml 中为 View 添加 id。

<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>
        <variable name="badge" type="parseJsonEntities.requestObjects.BadgeObject"/>
    </data>

    <LinearLayout
        android:orientation="vertical" android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:id="@+id/image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

    </LinearLayout>
</layout>

然后您就可以在 bindToViewHolder

@Override
public void bindToViewHolder(RecyclerView.ViewHolder viewHolder) {
    ProfileBadgeRowBinding binding = ((BadgeBindingHolder) viewHolder).binding;
    binding.setVariable(BR.badge, badge);
    binding.executePendingBindings();

    binding.image.setImage(...);
}

更多关于自定义 View https://developer.android.com/topic/libraries/data-binding/index.html#dynamic_variables

关于android - RecyclerView 和数据绑定(bind)不起作用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36634711/