如何知道 RecyclerView/LinearLayoutManager 是滚动到顶部还是底部? [英] How to know whether a RecyclerView / LinearLayoutManager is scrolled to top or bottom?

问题描述

目前我正在使用以下代码来检查是否应启用 SwipeRefreshLayout.

Currently I am using the follow code to check whether SwipeRefreshLayout should be enabled.

private void laySwipeToggle() {
    if (mRecyclerView.getChildCount() == 0 || mRecyclerView.getChildAt(0).getTop() == 0) {
        mLaySwipe.setEnabled(true);
    } else {
        mLaySwipe.setEnabled(false);
    }
}

但这就是问题所在.当它滚动到另一个项目的视图边界时 mRecyclerView.getChildAt(0).getTop() 也返回 0.

But here is the problem. When it's scrolled to another item's view's boundary mRecyclerView.getChildAt(0).getTop() also returns 0.

是否有类似 RecyclerView.isScrolledToBottom() 或 RecyclerView.isScrolledToTop() 之类的东西?

Is there something like RecyclerView.isScrolledToBottom() or RecyclerView.isScrolledToTop()?

(mRecyclerView.getChildAt(0).getTop() == 0 && linearLayoutManager.findFirstVisibleItemPosition() == 0) 类型的 RecyclerView.isScrolledToTop()，但是 RecyclerView.isScrolledToBottom() 呢?

(mRecyclerView.getChildAt(0).getTop() == 0 && linearLayoutManager.findFirstVisibleItemPosition() == 0) kind of does the RecyclerView.isScrolledToTop(), but what about RecyclerView.isScrolledToBottom()?

推荐答案

解决方案在布局管理器中.

The solution is in the layout manager.

LinearLayoutManager layoutManager = new LinearLayoutManager(this);

// Add this to your Recycler view
recyclerView.setLayoutManager(layoutManager);

// To check if at the top of recycler view
if(layoutManager.firstCompletelyVisibleItemPosition()==0){
    // Its at top
}

// To check if at the bottom of recycler view
if(layoutManager.lastCompletelyVisibleItemPosition()==data.size()-1){
    // Its at bottom
}

编辑

如果您的项目尺寸大于屏幕，请使用以下方法检测顶部事件.

In case your item size is larger than the screen use the following to detect the top event.

RecyclerView recyclerView = (RecyclerView) view;
LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();

int pos = linearLayoutManager.findFirstVisibleItemPosition();

if(linearLayoutManager.findViewByPosition(pos).getTop()==0 && pos==0){
    return true;
}

PS:实际上，如果您将 RecyclerView 直接放在 SwipeRefreshview 中，您就不需要这样做

PS: Actually, if you place the RecyclerView directly inside the SwipeRefreshview you wouldn't need to do this

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