recyclerview的adapter封装（kotlin）

首先是重写 ViewHolder，参考了鸿洋大神的博客。

class RViewHolder(private val mContext: Context, val convertView: View) : ViewHolder(convertView) {
   

    private val mViews: SparseArray<View>

    init {
   
        mViews = SparseArray()
    }

    /**
     * 通过viewId获取控件
     *
     * @param viewId
     * @return
     */
    fun <T : View> getView(viewId: Int): T {
   
        var view = mViews[viewId]
        if (view == null) {
   
            view = convertView.findViewById(viewId)
            mViews.put(viewId, view)
        }
        return view as T
    }

    /****以下为辅助方法 */
    /**
     * 设置TextView的值
     *
     * @param viewId
     * @param text
     * @return
     */
    fun setText(viewId: Int, text: String?): RViewHolder {
   
        val tv = getView<TextView>(viewId)
        tv.text = text
        return this
    }

    fun setImageResource(viewId: Int, resId: Int): RViewHolder {
   
        val view = getView<ImageView>(viewId)
        view.setImageResource(resId)
        return this
    }

    fun setImageBitmap(viewId: Int, bitmap: Bitmap?): RViewHolder {
   
        val view = getView<ImageView>(viewId)
        view.setImageBitmap(bitmap)
        return this
    }

    fun setImageDrawable(viewId: Int, drawable: Drawable?): RViewHolder {
   
        val view = getView<ImageView>(viewId)
        view.setImageDrawable(drawable)
        return this
    }

    fun setBackgroundColor(viewId: Int, color: Int): RViewHolder {
   
        val view = getView<View>(viewId)
        view.setBackgroundColor(color)
        return this
    }

    fun setBackgroundRes(viewId: Int, backgroundRes: Int): RViewHolder {
   
        val view = getView<View>(viewId)
        view.setBackgroundResource(backgroundRes)
        return this
    }

    fun setTextColor(viewId: Int, textColor: Int): RViewHolder {
   
        val view = getView<TextView>(viewId)
        view.setTextColor(textColor)
        return this
    }

    fun setTextColorRes(viewId: Int, textColorRes: Int): RViewHolder {
   
        val view = getView<TextView>(viewId)
        view.setTextColor(mContext.resources.getColor(textColorRes))
        return this
    }

    @SuppressLint("NewApi")
    fun setAlpha(viewId: Int, value: Float): RViewHolder {
   
        if (Build.