Question

首先，我从服务器读取数据并将其放入ArrayList中。接下来，我将ArrayList放入Adapter的{{1}}中。当用户到达末尾时，我想向服务器发送请求并获取RecyclerView的数据。现在，我做到了，它奏效了。但是，当我添加更多数据时，我的RecyclerView移到第一项，我必须向下滚动才能看到新数据...我想在RecyclerView的底部添加更多数据，而无需回到顶部。

这是我将请求发送到服务器并填写我的RecyclerView的方法：

ArrayList

这是我的private void getPosts(final Integer page, Integer limit) { getPosts(null, page, limit, new RemoteCallback<ResponseBody>() { @Override public void onSuccess(ResponseBody responseBody) { try { JSONArray data = new JSONArray(responseBody.string()); if (data.length() == 0) { Toast.makeText(getApplicationContext(), "Finish", Toast.LENGTH_LONG).show(); } else { for (int i = 0; i < data.length(); i++) { posts = getPosts_(data); } } } catch (Exception e) { } posts2.addAll(posts); } @Override public void onUnauthorized() { Log.e("data", "onUnauthorized"); } @Override public void onFailed(Throwable throwable) { Log.e("data", "onFailed"); } }); }：

Activity

这是我的public class MainActivity2 extends AppCompatActivity { private static int ITEM_REQUEST_INITIAL_OFFSET = 1; private static final int ITEM_REQUEST_LIMIT = 10; private APIService mAPIService; ProgressBar progressBar; RecyclerView recyclerView; AdapterContent item2RecyclerAdapter; private int mLoadedItems = 0; public static List<Post> posts = new ArrayList<Post>(); List<Post> posts2 = new ArrayList<Post>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main2); mAPIService = ApiUtils.getAPIService(); progressBar = findViewById(R.id.item_progress_bar); recyclerView = findViewById(R.id.recycler_view); getPosts(ITEM_REQUEST_INITIAL_OFFSET, ITEM_REQUEST_LIMIT); LinearLayoutManager linearLayoutManager = new LinearLayoutManager(MainActivity2.this); linearLayoutManager.setOrientation(LinearLayoutManager.VERTICAL); recyclerView.setLayoutManager(linearLayoutManager); recyclerView.addItemDecoration(new DividerItemDecoration(MainActivity2.this, DividerItemDecoration.VERTICAL)); recyclerView.setAdapter(adapter) item2RecyclerAdapter = new AdapterContent(posts2); recyclerView.addOnScrollListener(new EndlessRecyclerOnScrollListener() { @Override public void onLoadMore() { new Handler().postDelayed(new Runnable() { @Override public void run() { getPosts(ITEM_REQUEST_INITIAL_OFFSET, 10); } }, 1500); ITEM_REQUEST_INITIAL_OFFSET++; } }); }内容：

Adapter

我的问题是如何在不进入public class AdapterContent extends RecyclerView.Adapter<AdapterContent.SecondCollectionViewHolder> { private List<Post> posts; private Context context; private RemoteCallback<ResponseBody>remoteCallback; public SharedPreferences sp; public boolean state; public AdapterContent(List<Post> postList) { this.context = context; this.posts = postList; this.remoteCallback= remoteCallback; } @Override public AdapterContent.SecondCollectionViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View secondCollectionView = LayoutInflater.from(parent.getContext()).inflate(R.layout.row, parent, false); return new SecondCollectionViewHolder(secondCollectionView); } @Override public long getItemId(int position) { return super.getItemId(position); } @Override public void onBindViewHolder(final AdapterContent.SecondCollectionViewHolder secondHolder, final int position) { final Post post = posts.get(position); secondHolder.txt_postTitle.setText(post.getTitle()); Log.i("mhs",post.getTitle()); } public void add(Post r) { circleList.add(r); notifyItemInserted(posts.size() - 1); } public void addAll(ArrayList<Post> moveResults) { for (Post result : moveResults) { add(result); } } @Override public int getItemCount() { return posts.size(); } public class SecondCollectionViewHolder extends RecyclerView.ViewHolder { public TextView txt_postTitle; public RelativeLayout relativeLayout; public SecondCollectionViewHolder(View itemView) { super(itemView); txt_postTitle = (TextView) itemView.findViewById(R.id.txt_postTitle); } } }的第一行的情况下添加数据？

Answer 1

在列表末尾收到更多加载项时，使用自定义库或帮助程序的延迟加载实现

abstract class EndlessListener(private val carouselLayoutManager: CarouselLayoutManager) :
    RecyclerView.OnScrollListener() {

    private val visibleThreshold = 5
    private var currentPage = 0
    private var previousTotalItemCount = 0
    private var loading = true
    private var startingPageIndex = 0

    fun getLastVisibleItem(lastVisibleItemPositions: IntArray): Int {
        var maxSize = 0
        for (i in lastVisibleItemPositions.indices) {
            if (i == 0) {
                maxSize = lastVisibleItemPositions[i]
            } else if (lastVisibleItemPositions[i] > maxSize) {
                maxSize = lastVisibleItemPositions[i]
            }
        }
        return maxSize
    }

    override fun onScrolled(view: RecyclerView, dx: Int, dy: Int) {
        val lastVisibleItemPosition = (carouselLayoutManager as LinearLayoutManager).findLastVisibleItemPosition()
        val totalItemCount = carouselLayoutManager.itemCount

        if (totalItemCount < previousTotalItemCount) {
            currentPage = startingPageIndex
            previousTotalItemCount = totalItemCount
            if (totalItemCount == 0) {
                loading = true
            }
        }

        if (loading && totalItemCount > previousTotalItemCount) {
            loading = false
            previousTotalItemCount = totalItemCount
        }

        if (!loading && lastVisibleItemPosition + visibleThreshold > totalItemCount) {
            currentPage++
            onLoadMore(currentPage, totalItemCount, view)
            loading = true
        }
    }

    fun resetState() {
        this.currentPage = this.startingPageIndex
        this.previousTotalItemCount = 0
        this.loading = true
    }

    abstract fun onLoadMore(page: Int, totalItemsCount: Int, view: RecyclerView)

}

并添加一个侦听器以更改滚动位置

 recycelerView.addOnScrollListener(object : EndlessListener(layoutManager) {
                override fun onLoadMore(page: Int, totalItemsCount: Int, view: RecyclerView) {

                }
            })

滚动时将更多数据加载到recycleview中

1 个答案: