无法从 Kotlin 中的自定义 ResyclerView 扩展适配器

Question

我正在尝试基于此 post 实现一个空状态回收器视图。我已经将解决方案迁移到 Kotlin，但问题是我无法从Kotlin 中新定义的自定义回收器视图。我观察到相同的 CustomRecyclerView.Adapter 可以在 Java.

中扩展

自定义 RecyclerView 实现

open class CustomRecyclerView: RecyclerView {


private var emptyStateView : View? = null

constructor(context: Context) : super(context)
constructor(context: Context , attrs: AttributeSet) : super(context,attrs)
constructor(context: Context , attrs: AttributeSet, defstyle: Int) : super(context,attrs,defstyle)


var observer: AdapterDataObserver = object : AdapterDataObserver() {

    override fun onChanged() {
        super.onChanged()
        initEmptyView()
    }

    override fun onItemRangeRemoved(positionStart: Int, itemCount: Int) {
        super.onItemRangeRemoved(positionStart, itemCount)
        initEmptyView()
    }

    override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
        super.onItemRangeInserted(positionStart, itemCount)
        initEmptyView()
    }
}

private fun initEmptyView() {
    emptyStateView?.let {
        it.visibility = if (adapter == null || adapter!!.itemCount == 0) View.VISIBLE else View.GONE
        this@CustomRecyclerView.visibility = if (adapter == null || adapter!!.itemCount == 0) View.GONE else View.VISIBLE
    }
}

override fun setAdapter(adapter: Adapter<*>?) {
    val oldAdapter = getAdapter()
    super.setAdapter(adapter)
    oldAdapter?.unregisterAdapterDataObserver(observer)
    adapter?.registerAdapterDataObserver(observer)
}

/**
 * @param emptyView is the view which is going to display when the recycler view is empty
 * **/
fun setEmptyView(emptyView: View) {
    this.emptyStateView = emptyView
    initEmptyView()
}}

在 java 和 kotin

中为扩展实现添加图像

Answer 1

总结评论：继承自RecyclerView.Adapter，见下文

YourAdapter: RecyclerView.Adapter<YourViewHolder>()

提示一下，这里是使用多个构造函数扩展 class 的 Kotlin 方法：

class CustomRecyclerView @JvmOverloads constructor(
        context: Context,
        attrs: AttributeSet? = null,
        defStyleAttr: Int = 0
) : RecyclerView(context, attrs, defStyleAttr)

有关详细信息，请查看 @JvmOverloads

Answer 2

应该是RecyclerView.Adapter..并将适配器设置为customRecyclerView。

无法从 Kotlin 中的自定义 ResyclerView 扩展适配器

Not able to extend Adapter from a custom ResyclerView in Kotlin

java

android

abstract-class

kotlin

android-recyclerview

自定义 RecyclerView 实现