【Android】＜kotlin＞addOnScrollListenerを使ってリストの末尾付近で追加データを読み込む「無限スクロール (Infinite Scroll)」の実装例を紹介！

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

class InfiniteScrollListener(
    private val layoutManager: LinearLayoutManager,
    private val loadMore: () -> Unit
) : RecyclerView.OnScrollListener() {

    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)

        val visibleItemCount = recyclerView.childCount
        val totalItemCount = layoutManager.itemCount
        val firstVisibleItemPosition = layoutManager.findFirstVisibleItemPosition()

        if ((visibleItemCount + firstVisibleItemPosition) >= totalItemCount - 2) {
            loadMore()
        }
    }
}

recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.adapter = myAdapter  // ここでアダプターを設定

recyclerView.addOnScrollListener(
    InfiniteScrollListener(recyclerView.layoutManager as LinearLayoutManager) {
        fetchMoreData()  // 追加データの取得処理
    }
)

recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.adapter = myAdapter

// 以下の処理を追加
recyclerView.clearOnScrollListners()
recyclerView.addOnScrollListener(
    InfiniteScrollListener(recyclerView.layoutManager as LinearLayoutManager) {
        fetchMoreData()
    }
)