如何知道RecyclerView / LinearLayoutManager是滚动到顶部还是底部？
如何知道RecyclerView / LinearLayoutManager是滚动到顶部还是底部？
提问于 2015-01-08 21:53:07
目前，我正在使用以下代码检查是否应该启用SwipeRefreshLayout。
private void laySwipeToggle() {
if (mRecyclerView.getChildCount() == 0 || mRecyclerView.getChildAt(0).getTop() == 0) {
mLaySwipe.setEnabled(true);
} else {
mLaySwipe.setEnabled(false);
}
}但这里有个问题。当滚动到另一个项目的视图边界时，mRecyclerView.getChildAt(0).getTop()也返回0。
有没有像RecyclerView.isScrolledToBottom()或RecyclerView.isScrolledToTop()这样的东西
编辑：(mRecyclerView.getChildAt(0).getTop() == 0 && linearLayoutManager.findFirstVisibleItemPosition() == 0)有点像RecyclerView.isScrolledToTop()，但是RecyclerView.isScrolledToBottom()呢？
回答 7
Stack Overflow用户
发布于 2015-02-06 21:23:16
只需保留对layoutManager的引用，并在回收器视图上设置onScrollListener，如下所示
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
visibleItemCount = mRecyclerView.getChildCount();
totalItemCount = mLayoutManager.getItemCount();
firstVisibleItemIndex = mLayoutManager.findFirstVisibleItemPosition();
//synchronizew loading state when item count changes
if (loading) {
if (totalItemCount > previousTotal) {
loading = false;
previousTotal = totalItemCount;
}
}
if (!loading)
if ((totalItemCount - visibleItemCount) <= firstVisibleItemIndex) {
// Loading NOT in progress and end of list has been reached
// also triggered if not enough items to fill the screen
// if you start loading
loading = true;
} else if (firstVisibleItemIndex == 0){
// top of list reached
// if you start loading
loading = true;
}
}
}
});Stack Overflow用户
发布于 2017-04-11 18:13:36
您可以使用以下命令来检测top
recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
}
@Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
if(isRecyclerViewAtTop())
{
//your recycler view reached Top do some thing
}
}
});
private boolean isRecyclerViewAtTop() {
if(recyclerView.getChildCount() == 0)
return true;
return recyclerView.getChildAt(0).getTop() == 0;
}这将在您松开手指到达顶部时检测顶部，如果您希望在reacyclerview到达顶部时检测到顶部，请检查if(isRecyclerViewAtTop()) inside onScrolled方法
Stack Overflow用户
发布于 2017-02-06 11:07:12
我已经写了一个RecyclerViewHelper来知道回收器视图是在顶部还是底部。
public class RecyclerViewHelper {
public static boolean isAtTop(RecyclerView recyclerView) {
if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
return isAtTopBeforeIceCream(recyclerView);
} else {
return !ViewCompat.canScrollVertically(recyclerView, -1);
}
}
private static boolean isAtTopBeforeIceCream(RecyclerView recyclerView) {
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
if (layoutManager instanceof LinearLayoutManager) {
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
int pos = linearLayoutManager.findFirstVisibleItemPosition();
if (linearLayoutManager.findViewByPosition(pos).getTop() == recyclerView.getPaddingTop() && pos == 0)
return true;
}
return false;
}
public static boolean isAtBottom(RecyclerView recyclerView) {
if (android.os.Build.VERSION.SDK_INT < Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
return isAtBottomBeforeIceCream(recyclerView);
} else {
return !ViewCompat.canScrollVertically(recyclerView, 1);
}
}
private static boolean isAtBottomBeforeIceCream(RecyclerView recyclerView) {
RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
int count = recyclerView.getAdapter().getItemCount();
if (layoutManager instanceof LinearLayoutManager) {
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
int pos = linearLayoutManager.findLastVisibleItemPosition();
int lastChildBottom = linearLayoutManager.findViewByPosition(pos).getBottom();
if (lastChildBottom == recyclerView.getHeight() - recyclerView.getPaddingBottom() && pos == count - 1)
return true;
}
return false;
}}
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原文链接：
https://stackoverflow.com/questions/27841740
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