1

我正在从旧迁移ListView到RecyclerView我的项目中。我决定使用数据绑定来绑定列表值，但是在为我的文本框设置自定义文本跨度时遇到了一些问题。

请看这段代码（这是用旧的 ListBox 适配器完成的）：

@Override
public View getView(int position, @Nullable View convertView, ViewGroup parent) {
    ...

    Typeface tf = Typeface.createFromAsset(convertView.getContext().getAssets(), "fonts/fontawesome.ttf");
    SpannableStringBuilder textCategory = new SpannableStringBuilder((item != null ? item.getCategoryIconName() : null) + "     " + item.getCategoryName());
    textCategory.setSpan (new CustomTypefaceSpan("", tf), 0, 1, Spanned.SPAN_EXCLUSIVE_INCLUSIVE);

    viewHolder.eventCategory.setText(textCategory);

    ...
}

基本上， myCustomTypeFaceSpan用于为单个TextView. 如何使用数据绑定实现相同的功能？可以BindingAdapter用于那个吗？

我的尝试：

<variable name="categoryText" type="String"/>
<variable name="data" type="Event"/>

<TextView
                android:id="@+id/event_category_text"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginLeft="32dp"
                android:layout_marginRight="8dp"
                android:layout_marginTop="16dp"
                android:paddingBottom="3dp"
                android:paddingTop="3dp"
                android:text="@{data.categoryIconName + data.categoryName}"
                android:textAppearance="@style/TextAppearance.AppCompat.Body2"
                android:textColor="@color/colorEventCategoryText"
                app:customFunction="@{categoryText}"
                app:layout_constraintLeft_toLeftOf="parent"
                app:layout_constraintRight_toRightOf="parent"
                app:layout_constraintTop_toTopOf="parent"/>

绑定适配器：

@BindingAdapter({"customFunction"})
    public static void setSpan(TextView textView, String categoryText)
    {
        Typeface tf = Typeface.createFromAsset(textView.getContext().getAssets(), "fonts/fontawesome.ttf");
        SpannableStringBuilder textCategory = new SpannableStringBuilder(categoryText);
        textCategory.setSpan (new CustomTypefaceSpan("", tf), 0, 1, Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
        textView.setText(textCategory);
    }

问题：categoryText始终为空。有任何想法吗？TextView 已正确绑定，因为没有自定义功能，它会按应有的方式显示文本。

我的列表适配器：

public class ListAdapter extends RecyclerView.Adapter<ListAdapter.ViewHolder>
{
    public List<Event> events = null;
    private final ListFragment.OnFragmentInteractionListener mListener;

    public ListAdapter(List<Event> events, ListFragment.OnFragmentInteractionListener mListener)
    {
        this.events = events;
        this.mListener = mListener;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType)
    {

        LayoutInflater layoutInflater = LayoutInflater.from(viewGroup.getContext());
        ViewDataBinding binding = DataBindingUtil.inflate(layoutInflater, R.layout.cell, viewGroup, false);
        return new ViewHolder(binding);
    }


    @Override
    public void onBindViewHolder(ViewHolder viewHolder, final int position)
    {

        final Event event = events.get(position);
        viewHolder.bind(event);

        viewHolder.binding.getRoot().setOnClickListener(v ->
        {
            if (null != mListener)
            {
                mListener.onFragmentInteraction(event);
            }
        });
    }

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


    public static class ViewHolder extends RecyclerView.ViewHolder
    {
        private final ViewDataBinding binding;

        public ViewHolder(ViewDataBinding binding)
        {
            super(binding.getRoot());
            this.binding = binding;
        }

        public void bind(Object obj)
        {
            binding.setVariable(BR.data,obj);
            binding.executePendingBindings();
        }
    }
}
4

1 回答 1

2

使用自定义属性，例如：

在 xml 中： 

<data>
  <variable
      name="name"
      type="String"></variable>
</data>
........
  <TextView
     android:id="@+id/textView2"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:layout_margin="20dp"
     app:customFunction="@{name}"
    />

在活动课上

.............
ActivityMainBinding binding = DataBindingUtil........
binding.setName("Something");
...................
@BindingAdapter("customFunction")
public static void myCustomFunction(TextView textView, String name){
    Log.d("MainActivity", "custom function called");
    String nameCaps = name.toUpperCase();
    textView.setText(nameCaps);
}

myCustomFunction(..)当从 xml 创建 Textview 时将被调用。您可以使用自定义函数将 Span 设置为您的视图。

于 2017-07-10T11:25:14.027 回答