RecyclerView有一个InfiniteScrollListener，在该监听器内，在OnScrolled()方法中，我计算可见项和总项数，以检查是否应加载新项。当totalItemCount和visibleItemCount相同时，它会导致无限循环加载。听众与我没有RecyclerView或CoordinatorLayout作为父母的其他NestedScrollView完美无瑕。
我希望保留这种结构，因为客户不会接受改变。
我在活动中有一个像这样的布局的片段
CoordinatorLayout{
NestedScrollView{
RecyclerView{
}
}
}
compileSdkVersion 24
buildToolsVersion "23.0.3"
...
minSdkVersion 21
targetSdkVersion 24
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.design.widget.AppBarLayout
android:id="@+id/app_bar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:theme="@style/AppTheme.AppBarOverlay"
app:layout_behavior="com.paxotic.paxira.util.behavior.AppBarFlingBehavior">
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/toolbar_layout"
android:layout_width="match_parent"
android:layout_height="@dimen/app_bar_height_small"
app:contentScrim="?attr/colorPrimary"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000000"
app:layout_collapseMode="parallax">
<ImageView
android:id="@+id/img_background"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:alpha="0.5"
android:scaleType="centerCrop"
tools:src="@drawable/bg_greeting_activity" />
</RelativeLayout>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<include
layout="@layout/activity_profile_content"
app:layout_behavior="@string/appbar_scrolling_view_behavior" />
<android.support.design.widget.FloatingActionButton
... />
</android.support.design.widget.CoordinatorLayout>
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="@string/appbar_scrolling_view_behavior">
...
<android.support.v7.widget.RecyclerView
android:id="@+id/feedRecycler"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipToPadding="false"
android:paddingBottom="@dimen/spacing_normal"
tools:listitem="@layout/list_item_activity" />
...
</android.support.v4.widget.NestedScrollView>
private void init() {
feedAdapter = new FeedAdapter(host);
feedAdapter.setHasStableIds(true);
LinearLayoutManager layoutManager = new LinearLayoutManager(host);
feedRecycler.setLayoutManager(layoutManager);
feedRecycler.setNestedScrollingEnabled(false);
feedRecycler.setHasFixedSize(true);
feedRecycler.setAdapter(feedAdapter);
infiniteScrollListener = new InfiniteScrollListener(host, layoutManager) {
@Override
public void onLoadMore(int pageIndex) {
if (!feedAdapter.isLoading) {
loadFeed(pageIndex);
}
}
};
feedRecycler.addOnScrollListener(infiniteScrollListener);
}
public abstract class InfiniteScrollListener extends RecyclerView.OnScrollListener {
private int previousTotal = 0; // The total number of items in the dataset after the last load
private boolean loading = false; // True if we are still waiting for the last set of data to load.
private static final int VISIBLE_THRESHOLD = 5; // The minimum amount of items to have below your current scroll position before loading more.
int firstVisibleItem, visibleItemCount, totalItemCount;
private int current_page = 0;
private int loadingItemCount;
private LinearLayoutManager mLinearLayoutManager;
public InfiniteScrollListener(Context context, LinearLayoutManager linearLayoutManager) {
this.mLinearLayoutManager = linearLayoutManager;
loadingItemCount = context.getResources().getInteger(R.integer.feed_pull_item_count);
}
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
if (dy < 0) return; // check for scroll down
visibleItemCount = mLinearLayoutManager.getChildCount();
totalItemCount = mLinearLayoutManager.getItemCount();
firstVisibleItem = mLinearLayoutManager.findFirstVisibleItemPosition();
synchronized (this) {
if (!loading && (totalItemCount - visibleItemCount) <= (firstVisibleItem + VISIBLE_THRESHOLD)) {
// End has been reached, Do something
current_page++;
onLoadMore(current_page);
loading = true;
}
}
}
public abstract void onLoadMore(int current_page);
public void setLoading(boolean loading) {
this.loading = loading;
}
@Override
public void onScrollStateChanged(RecyclerView view, int scrollState) {
// Don't take any action on changed
}
}
答案 0 :(得分：1)
您从 getChildCount() getItemCount() 获得相同的值，因为 recyclerview 将返回项目/子项的总数。
您必须根据您的使用情况重写其中一种方法，以获得您想要的值。 在您的自定义 recyclerview 适配器中执行此操作。
为此，请将其添加到您的 recyclerview 适配器：
@Overide
public int getChildCount() {
//return your desired value here after obtaining it
}
答案 1 :(得分：1)
您可以获得真实的观看次数。如果适配器有 15 个项目，并且 ((LinearLayoutManager) myRecyclerView.getLayoutManager()).getChildCount() 返回 7，则在更新新项目后，由于最大高度或静态高度值，视图中有两个项目可见，直到保持相同的高度。
模型（适配器）中的项目数和视图数不是一回事。
RecyclerView doesn't hold views for all 15 items in memory, it only has 7 in your case. When you scroll, it reuses those 7 views for displaying different items. The purpose of this is improving the rendering performance.
如果你想得到 15，那么你应该使用 mAdapter.getItemCount() 代替。
答案 2 :(得分：0)
您不应该在recyclerView中使用nestedScrollview垂直。
用于查找要显示在RecyclerView上的夹心物品并开始获取新物品
您可以使用适配器。在RecyclerView.Adapter<>中，您可以覆盖onViewAttachedToWindow()：
@Override
public void onViewAttachedToWindow(@NonNull RecyclerView.ViewHolder holder) {
super.onViewAttachedToWindow(holder);
if ((getItemCount() - 1) == holder.getAdapterPosition()){
Log.d(TAG,"list done");
onLoadMore(current_page);
} else {
Log.d(TAG,"remain item : " + (getItemCount() - holder.getAdapterPosition() - 1));
}
}