无法使用 Android 绑定在 RecyclerView 上绑定 RatingBar答案

【问题标题】：Can't bind a RatingBar on the RecyclerView using Android binding无法使用 Android 绑定在 RecyclerView 上绑定 RatingBar
【发布时间】：2019-09-23 10:16:53
【问题描述】：

我正在使用 kotlin 绑定放置在 RecyclerView 上的 RatingBar，但出现以下错误：

在 android.widget.RatingBar 上找不到参数类型为 java.lang.Double 的属性“app:ratingValue”的设置器。

我尝试关注不同的博客来设置 RatingBar 的值，但我无法在适配器中实现它。

下面是我的模型类：

@Entity(tableName = "Results")
class Result {

    companion object {

        @JvmStatic
        @BindingAdapter("ratingValue")
        fun setRating(ratingBar: RatingBar, mVoteAverage: Float) {
            if (mVoteAverage != null) {
                ratingBar.rating = mVoteAverage
                val stars = ratingBar.progressDrawable as LayerDrawable
                stars.getDrawable(2).setColorFilter(ContextCompat.getColor(ratingBar.context, R.color.rating_bar), PorterDuff.Mode.SRC_ATOP)
                val roundVal = Math.round(mVoteAverage!!)
                ratingBar.numStars = roundVal
            }

        }
    }

    constructor(mId: Long?, mOverview: String?, mPosterPath: String?, mTitle: String?, mVoteAverage: Double?) {
        this.mId = mId
        this.mOverview = mOverview
        this.mPosterPath = mPosterPath
        this.mTitle = mTitle
        this.mVoteAverage = mVoteAverage
    }

    constructor()

    @PrimaryKey
    @SerializedName("id")
    var mId: Long? = null
    @SerializedName("overview")
    var mOverview: String? = null
    @SerializedName("poster_path")
    var mPosterPath: String? = null
    @SerializedName("title")
    var mTitle: String? = null
    @SerializedName("vote_average")
    var mVoteAverage: Double? = null


}

那么，这就是可绑定的 XML 布局：

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

        <variable
            name="movie"
            type="com.movieapp.huxymovies.model.Result" />
    </data>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:background="@color/bg"
        android:orientation="vertical">

                    <LinearLayout
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:orientation="horizontal">

                        <RatingBar
                            android:id="@+id/rating_bar"
                            style="?android:attr/ratingBarStyleSmall"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_marginTop="9dp"
                            app:ratingValue="@{movie.mVoteAverage}"/>


                    </LinearLayout>


            </LinearLayout>
    </LinearLayout>
</layout>

那么这是我的适配器类：

class ResultAdapter(private val context: Context) : PagedListAdapter<Result, ResultAdapter.ResultViewHolder>(DIFF_CALLBACK) {

    public lateinit var mBinding: ItemActivitymainBinding

    override fun onBindViewHolder(holder: ResultViewHolder, position: Int) {

        val result = getItem(position)

        if (result != null) {

            holder.itemActivitymainBinding.movie = result
            holder.itemActivitymainBinding.ratingBar.rating = result.mVoteAverage as (Float)
            holder.itemActivitymainBinding.titleTxt.text = result.mTitle

        }
    }

    class ResultViewHolder(itemView: ItemActivitymainBinding) : RecyclerView.ViewHolder(itemView.root) {


        var itemActivitymainBinding: ItemActivitymainBinding
        var root: View

        init {
            root = itemView.root

            itemActivitymainBinding = itemView
        }
    }

    }
}

我认为onBindViewHolder() 中遗漏了一些内容，但找不到，我遗漏了什么？

【问题讨论】：

标签： android kotlin android-databinding android-binding-adapter

【解决方案1】：

Result 类的mVoteAverage: Double? 属性是Double。你的@BindingAdapter 方法有一个Float 参数。这就是绑定不起作用的原因。改变

    @JvmStatic
    @BindingAdapter("ratingValue")
    fun setRating(ratingBar: RatingBar, mVoteAverage: Float)

到

    @JvmStatic
    @BindingAdapter("ratingValue")
    fun setRating(ratingBar: RatingBar, mVoteAverage: Double)

应该可以解决问题。

【讨论】：