java - 如何使 fab 在向上滚动开始时可见并在向下滚动开始时隐藏

Question

我想让 fab 在向下滚动开始时立即隐藏，并在向上滚动开始时立即显示，我该怎么做，现在我正在尝试这个，但它仅在到达顶部时出现，在到达底部时隐藏:

 @Override
public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child, final View directTargetChild, final View target, final int nestedScrollAxes) {
    // Ensure we react to vertical scrolling
    return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
            || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
}

@Override
public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child, final View target, final int dxConsumed, final int dyConsumed, final int dxUnconsumed, final int dyUnconsumed) {
    super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);

    if (CoordinatorLayout.SCROLL_INDICATOR_START == 16 && dyConsumed > 0 && child.getVisibility() == View.VISIBLE) {
        child.hide();
    } else if (CoordinatorLayout.SCROLL_INDICATOR_START == 16 && dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
        child.show();
    }
} 

Answer 1

如果您的布局中有 recyclerView，此代码将为您提供帮助:

recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {
        override fun onScrolled(recyclerView: RecyclerView?, dx: Int, dy: Int) {
            if (dy > 0) {
                fab?.hide()
            } else if (dy < 0) {
                fab?.show()
            }
        }
    })