android - RecyclerView.addOnScrolledToEnd 和 SwipeRefreshLayout.setOnRefreshListener 在 Kotlin 中无法正常工作

Question

我已经实现了 RecyclerView.addOnScrolledToEnd 以使用异步任务从服务器获取下一组数据。仅使用 RecyclerView.addOnScrolledToEnd 时它工作正常。但是这里我的问题是一旦我到达终点并且我做了 SwipeRefreshLayout.setOnRefreshListener (这里将数据重置为新记录) RecyclerView.addOnScrolledToEnd 没有调用并且分页没有在这种情况下工作。

fragment

    class RecentNewsFragment : Fragment(), LoaderManager.LoaderCallbacks<Cursor>, NewsAdapter.OnNewsCallBack, OnRefreshCallback {
    private var rlProgressContainer: View? = null
    private var listContainer: View? = null
    private var pbViewMore: ProgressBar? = null
    private var swipeRefreshLayout: SwipeRefreshLayout? = null
    private var srlNoMessageRefreshLayout: SwipeRefreshLayout? = null
    private var newsAdapter: NewsAdapter? = null
    private var pageLimit: Int = 10
    private var pageOffset: Int = 0
    private var totalNewsCount: Int = 0
    private var isAsyncDone: Boolean = false

    private val mRecentNewsBroadCast = object : BroadcastReceiver() {
        override fun onReceive(context: Context, intent: Intent) {
            // Get extra data included in the Intent
            restartLoader()

        }
    }


    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        // Inflate the layout for this fragment
        val view = inflater.inflate(R.layout.fragment_recent_news, container, false)
        initView(view)
        return view
    }

    override fun onResume() {
        super.onResume()
        if(!Helper.isConnected(context!!)) {
            Toast.makeText(context!!, context?.getString(R.string.no_connection), Toast.LENGTH_SHORT).show()
        }
    }

    private fun initView(view: View) {
        rlProgressContainer = view.findViewById(R.id.rl_progressContainer)
        listContainer = view.findViewById(R.id.ll_list_container)
        pbViewMore = view.findViewById(R.id.pb_view_more)
        newsAdapter = NewsAdapter(context!!, null, this)
        val recyclerView = view.findViewById<RecyclerView>(R.id.recycler_view)
        recyclerView.layoutManager = LinearLayoutManager(context)
        recyclerView.adapter = newsAdapter

        recyclerView.addItemDecoration(DividerItemDecoration(context!!, DividerItemDecoration.VERTICAL))
        recyclerView.setHasFixedSize(true)
        recyclerView.itemAnimator = DefaultItemAnimator()

        pbViewMore!!.visibility = View.GONE
        srlNoMessageRefreshLayout = view.findViewById(R.id.srl_activities_no_message)
        srlNoMessageRefreshLayout!!.visibility = View.GONE
        swipeRefreshLayout = view.findViewById(R.id.swipe_refresh_feeds_page)

        val pullToRefresh = PullToRefresh()
        swipeRefreshLayout!!.setColorSchemeResources(android.R.color.holo_green_dark, android.R.color.holo_red_dark, android.R.color.holo_orange_dark, android.R.color.holo_purple)
        swipeRefreshLayout!!.setOnRefreshListener(pullToRefresh)

        srlNoMessageRefreshLayout!!.setColorSchemeResources(android.R.color.holo_green_dark, android.R.color.holo_red_dark, android.R.color.holo_orange_dark, android.R.color.holo_purple)
        srlNoMessageRefreshLayout!!.setOnRefreshListener(pullToRefresh)
        listContainer!!.visibility = View.GONE
        rlProgressContainer!!.visibility = View.VISIBLE

        loaderManager.initLoader(Constants.URL_RECENT_NEWS_LOADER, arguments, this)

        startAsync(pageLimit, pageOffset)

        fun RecyclerView.addOnScrolledToEnd(onScrolledToEnd: () -> Unit){

            this.addOnScrollListener(object: RecyclerView.OnScrollListener(){

                private val visibleThreshold = 5

                private var loading = true
                private var previousTotal = 0

                override fun onScrollStateChanged(recyclerView: RecyclerView,
                                                  newState: Int) {

                    with(layoutManager as LinearLayoutManager){

                        val visibleItemCount = childCount
                        val totalItemCount = itemCount
                        val firstVisibleItem = findFirstVisibleItemPosition()

                        if (loading && totalItemCount > previousTotal){

                            loading = false
                            previousTotal = totalItemCount
                        }

                        if(!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + visibleThreshold)){

                            onScrolledToEnd()
                            loading = true
                        }
                    }
                }
            })
        }

        recyclerView.addOnScrolledToEnd {
            //What you want to do once the end is reached
            pbViewMore!!.visibility = View.VISIBLE
            startAsync(pageLimit, pageOffset)
        }

    }


    private inner class PullToRefresh : SwipeRefreshLayout.OnRefreshListener {
        override fun onRefresh() {
            pbViewMore!!.visibility = View.GONE
            pageOffset = 0
            startAsync(pageLimit, pageOffset)
            srlNoMessageRefreshLayout!!.isRefreshing = false
            swipeRefreshLayout!!.isRefreshing = false
        }
    }

    private fun startAsync(pageLimit: Int, pageOffset: Int) {
        if(Helper.isConnected(context!!)) {
            val recentAsync = RecentNewsAsync(context = this, pageLimit = pageLimit, pageOffset = pageOffset)
            recentAsync.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)
        } else {
            isAsyncDone = true
        }
    }

    fun restartLoader() {
        if(isAdded)
            loaderManager.restartLoader(Constants.URL_RECENT_NEWS_LOADER, null, this)
    }

    override fun onCreateLoader(id: Int, args: Bundle?): Loader<Cursor> {
        return NewsVo.getCursorLoader(context!!, NewsVo.NewsType.RECENT, 0)
    }

    override fun onLoadFinished(loader: Loader<Cursor>, cursor: Cursor?) {
        if (loader.id == Constants.URL_RECENT_NEWS_LOADER) {
            if(isAsyncDone) {
                listContainer!!.visibility = View.VISIBLE
                rlProgressContainer!!.visibility = View.GONE
            }
            if (cursor != null) {
                newsAdapter!!.swapCursor(cursor)
                newsAdapter!!.notifyDataSetChanged()
                if (isAsyncDone && cursor.count > 0) {
                    srlNoMessageRefreshLayout!!.visibility = View.GONE
                    swipeRefreshLayout!!.visibility = View.VISIBLE
                } else if(isAsyncDone){
                    srlNoMessageRefreshLayout!!.visibility = View.VISIBLE
                    swipeRefreshLayout!!.visibility = View.GONE
                }
            }
        }
    }

    override fun onLoaderReset(loader: Loader<Cursor>) {
        newsAdapter!!.swapCursor(null)

    }


    private class RecentNewsAsync internal constructor(context: RecentNewsFragment, private val pageLimit: Int, private val pageOffset: Int) : AsyncTask<Void, Void, Response<ArrayList<NewsVo>>>() {

        private val context: WeakReference<RecentNewsFragment> = WeakReference(context)

        override fun doInBackground(vararg p0: Void?): Response<ArrayList<NewsVo>> {
            var response = Response<ArrayList<NewsVo>>()
            try {
                val lphService = LPHServiceFactory.getCALFService(context.get()?.context!!)
                response = lphService.recentNews(pageLimit, pageOffset)
            } catch (e: LPHException) {
                e.printStackTrace()
                response.setThrowable(e)
            } catch (e: JSONException) {
                e.printStackTrace()
                response.setThrowable(e)
            } catch (e: IOException) {
                e.printStackTrace()
                response.setThrowable(e)
            }

            return response
        }

        override fun onPostExecute(response: Response<ArrayList<NewsVo>>) {
            super.onPostExecute(response)
            context.get()?.isAsyncDone = true
            context.get()?.pbViewMore?.visibility = View.GONE
            if (response.isSuccess()) {
                context.get()?.totalNewsCount = response.getMetaData() as Int
                if(context.get() != null)
                    context.get()!!.pageOffset += response.getResult()?.size!!

                context.get()?.restartLoader()
            }
        }
    }

    override fun onFavoriteClick(newsId: Int, isFavorite: Boolean) {
        if(Helper.isConnected(context!!)) {
            val weakReferenceContext = WeakReference(this.context!!)
            val markFavoriteAsync = Helper.MarkFavoriteAsync(weakReferenceContext, newsId, isFavorite, this, 0)
            markFavoriteAsync.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)
        } else {
            Helper.showConfirmationAlertTwoButton(context!!, context!!.getString(R.string.internet_warning), object : ConfirmationAlertCallback {
                override fun onPositiveButtonClick() {
                    onFavoriteClick(newsId, isFavorite)
                }

                override fun onNegativeButtonClick() {

                }

                override fun onNeutralButtonClick() {

                }
            })
        }
    }

    override fun setRead(newsId: Int, isRead: Boolean) {
        if(Helper.isConnected(context!!)) {
            val weakReferenceContext = WeakReference(context!!)
            val markReadAsync = Helper.MarkReadAsync(weakReferenceContext, newsId, isRead, this, 0)
            markReadAsync.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR)
        } else {
            Helper.showConfirmationAlertTwoButton(context!!, context!!.getString(R.string.internet_warning), object : ConfirmationAlertCallback {
                override fun onPositiveButtonClick() {
                    setRead(newsId, isRead)
                }

                override fun onNegativeButtonClick() {

                }

                override fun onNeutralButtonClick() {

                }
            })
        }
    }

    override fun onViewClick(newsId: Int) {
        val newsDetailIntent = Intent(context, NewsDetailActivity::class.java)
        newsDetailIntent.putExtra(Constants.BUNDLE_NEWS_ID, newsId)
        startActivityForResult(newsDetailIntent, Constants.REQUEST_CODE_RECENT_NEWS)
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        activity!!.registerReceiver(mRecentNewsBroadCast, IntentFilter(Constants.BROADCAST_RECENT_NEWS))
    }

    override fun onDetach() {
        super.onDetach()
        activity!!.unregisterReceiver(mRecentNewsBroadCast)
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == Constants.REQUEST_CODE_RECENT_NEWS && resultCode == Activity.RESULT_OK) {
            restartLoader()
            val intent1 = Intent(Constants.BROADCAST_FAVORITE_NEWS)
            context!!.sendBroadcast(intent1)

            val intent2 = Intent(Constants.BROADCAST_CATEGORIES)
            context!!.sendBroadcast(intent2)
        }
    }

    override fun onRefresh() {
        restartLoader()
        val intent1 = Intent(Constants.BROADCAST_FAVORITE_NEWS)
        context!!.sendBroadcast(intent1)

        val intent2 = Intent(Constants.BROADCAST_CATEGORIES)
        context!!.sendBroadcast(intent2)
    }

    companion object {

        /**
         * Use this factory method to create a new instance of
         * this fragment using the provided parameters.
         *
         * @return A new instance of fragment RecentNewsFragment.
         */
        fun newInstance(): RecentNewsFragment {
            return RecentNewsFragment()
        }
    }
}

布局文件:

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:id="@+id/ll_list_container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="horizontal">

        <android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/srl_activities_no_message"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="gone">

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

                <TextView
                    android:id="@+id/tv_no_data_found"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:enabled="false"
                    android:fontFamily="sans-serif-light"
                    android:gravity="center"
                    android:text="@string/no_data"
                    android:textAppearance="?android:attr/textAppearanceMedium"
                    android:textColor="@android:color/black" />
            </LinearLayout>
        </android.support.v4.widget.SwipeRefreshLayout>

        <android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/swipe_refresh_feeds_page"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:fitsSystemWindows="false"
            android:visibility="visible">

            <RelativeLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent">

                <android.support.v7.widget.RecyclerView
                    android:id="@+id/recycler_view"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent" />

                <ProgressBar
                    android:id="@+id/pb_view_more"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_alignParentBottom="true"
                    android:layout_centerInParent="true"
                    android:layout_gravity="center_horizontal"
                    android:theme="@style/ProgressBarTheme"
                    android:visibility="gone" />

            </RelativeLayout>


        </android.support.v4.widget.SwipeRefreshLayout>
    </LinearLayout>

    <RelativeLayout
        android:id="@+id/rl_progressContainer"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:visibility="gone">

        <ProgressBar
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_centerInParent="true"
            android:layout_centerVertical="true"
            android:theme="@style/ProgressBarTheme" />
    </RelativeLayout>

</LinearLayout>

Answer 1

这是 Recyclerview 的无限滚动，我从 here 得到它

public abstract class EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener {
/**
 * The total number of items in the dataset after the last load
 */
private int mPreviousTotal = 0;
/**
 * True if we are still waiting for the last set of data to load.
 */
private boolean mLoading = true;

@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    super.onScrolled(recyclerView, dx, dy);

    int visibleItemCount = recyclerView.getChildCount();
    int totalItemCount = recyclerView.getLayoutManager().getItemCount();
    int firstVisibleItem = ((LinearLayoutManager) recyclerView.getLayoutManager()).findFirstVisibleItemPosition();

    if (mLoading) {
        if (totalItemCount > mPreviousTotal) {
            mLoading = false;
            mPreviousTotal = totalItemCount;
        }
    }
    int visibleThreshold = 5;
    if (!mLoading && (totalItemCount - visibleItemCount)
            <= (firstVisibleItem + visibleThreshold)) {
        // End has been reached

        onLoadMore();

        mLoading = true;
    }
}

public abstract void onLoadMore();

我在 Kotlin MVP 模式中使用它

 rcyView_matches.addOnScrollListener(object : EndlessRecyclerOnScrollListener() {
        override fun onLoadMore() {

            item_progress_bar.setVisibility(View.VISIBLE)
            offset = offset + 10
            homeModel.matchesParametre(CommonUtility.getGlobalString(activity as Activity, "userId"), "" + offset)

        }
    })

和 Adapter Insilization，最初我膨胀空列表并在覆盖方法中添加列表之后。

 override fun matchesList(list: ArrayList<ProfileSelectedData>) {
    avlodder.hide()
    iv_nodata.visibility = View.GONE
    matcheslist.addAll(list)
    adapter.notifyDataSetChanged()
    item_progress_bar.setVisibility(View.GONE)
}