'scrollBy(int, androidx.recyclerview.widget.RecyclerView.Recycler, androidx.recyclerview.widget.RecyclerView.State)' is not public in 'androidx.recyclerview.widget.LinearLayoutManager'. Cannot be accessed from outside package

抱歉，我的回答还是有误。这是因为scrollBy是LinearLayoutManager的一个非公开的方法，只能在LinearLayoutManager内部使用，不能从外部访问。因此，我们需要通过其他方式来实现RecyclerView的平滑滚动。以下是一个基于Scroller类的实现方法： ``` public void smoothScrollBy(int dx, int dy) { RecyclerView.SmoothScroller smoothScroller = new LinearSmoothScroller(getContext()) { @Override public PointF computeScrollVectorForPosition(int targetPosition) { return LinearLayoutManager.this.computeScrollVectorForPosition(targetPosition); } }; smoothScroller.setTargetPosition(getPositionForVelocity(dx, dy)); startSmoothScroll(smoothScroller); } protected int getPositionForVelocity(int dx, int dy) { if (getChildCount() == 0) { return 0; } final View nearestChild = findNearestChild(); if (nearestChild == null) { return 0; } final int currentPosition = getPosition(nearestChild); if (currentPosition == RecyclerView.NO_POSITION) { return 0; } final int direction = computeScrollDirectionForPosition(currentPosition, dx, dy); if (direction == RecyclerView.NO_POSITION) { return 0; } final int targetPosition = currentPosition + direction; if (targetPosition < 0 || targetPosition >= getItemCount()) { return 0; } return targetPosition; } protected int computeScrollDirectionForPosition(int targetPosition, int dx, int dy) { if (getChildCount() == 0) { return RecyclerView.NO_POSITION; } final View firstChild = getChildAt(0); if (firstChild == null) { return RecyclerView.NO_POSITION; } final int currentPosition = getPosition(firstChild); if (currentPosition == RecyclerView.NO_POSITION) { return RecyclerView.NO_POSITION; } final int direction = getScrollDirectionForPosition(currentPosition, targetPosition); if (direction == RecyclerView.NO_POSITION) { return RecyclerView.NO_POSITION; } final int distance = computeDistanceToPosition(targetPosition); if (distance == 0) { return RecyclerView.NO_POSITION; } return (int) Math.ceil((double) distance / (double) getDistancePerChild()); } protected int getDistancePerChild() { return Math.round(getChildAt(0).getHeight() * 1.0f); } protected int computeDistanceToPosition(int targetPosition) { final int targetChildIndex = targetPosition - getPosition(getChildAt(0)); return targetChildIndex * getDistancePerChild(); } protected int getScrollDirectionForPosition(int currentPosition, int targetPosition) { return targetPosition < currentPosition ? -1 : 1; } protected View findNearestChild() { final int childCount = getChildCount(); if (childCount == 0) { return null; } View nearestChild = null; int nearestDistance = Integer.MAX_VALUE; final int centerX = getWidth() / 2; final int centerY = getHeight() / 2; for (int i = 0; i < childCount; i++) { final View child = getChildAt(i); final int distanceX = Math.abs(getLeftDecorationWidth(child) + getRightDecorationWidth(child) + child.getMeasuredWidth() / 2 - centerX); final int distanceY = Math.abs(getTopDecorationHeight(child) + getBottomDecorationHeight(child) + child.getMeasuredHeight() / 2 - centerY); final int distance = distanceX * distanceX + distanceY * distanceY; if (distance < nearestDistance) { nearestChild = child; nearestDistance = distance; } } return nearestChild; } ``` 这个实现方法是通过LinearSmoothScroller来实现的，首先创建一个LinearSmoothScroller对象，然后设置目标位置，最后启动平滑滚动。在getPositionForVelocity、computeScrollDirectionForPosition、computeDistanceToPosition和findNearestChild等函数中，实现了计算滚动距离、滚动方向、目标位置和最近的子View等功能。