Returns the resolved layout direction for this RecyclerView. @return {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_RTL} if the layout di

Time base for deadline-aware work scheduling. Overridable for testing. Will return 0 to avoid cost of System.nanoTime where deadline-aware work sched

Calculates the bounding box of the View while taking into account its matrix changes (translation, scale etc) with respect to the RecyclerView. <p> If

Returns true if the RecyclerView this LayoutManager is bound to has or contains focus. @return true if the RecyclerView has or contains focus @see Vi

Used for debugging. Logs the internal representation of children to default logger.

Called when the scroll state of this RecyclerView changes. Subclasses should use this method to respond to state changes instead of an explicit listen

Recycles children between given indices. @param startIndex inclusive @param endIndex exclusive

Removes all views and recycles them using the given recycler. <p> If you want to clean cached views as well, you should call {@link Recycler#clear()}

Calculates the view layout order. (e.g. from end to start or start to end) RTL layout support is applied automatically. So if layout is RTL and {@link

Scroll to the specified adapter position with the given offset from resolved layout start. Resolved layout start depends on {@link #getReverseLayout()

Animate a scroll by the given amount of pixels along either axis. @param dx Pixels to scroll horizontally @param dy Pixels to scroll vertically

Stop any current scroll in progress, such as one started by {@link #smoothScrollBy(int, int)}, {@link #fling(int, int)} or a touch-initiated fling.

assigns anchor coordinate from the RecyclerView's padding depending on current layoutFromEnd value

Skips pre-processing and applies all updates in one pass.

Used when onMeasure is called before layout manager is set

Convenience method to find the visible child closes to end. Caller should check if it has enough children. @param completelyVisible Whether child sho

Convenience method to find the visible child closes to start. Caller should check if it has enough children. @param completelyVisible Whether child s

Returns the space occupied by this View in the perpendicular orientation including decorations and margins. @param view The view element to check @re

Returns the current number of Views held by the RecycledViewPool of the given view type.

Returns the adapter position of the target item @return Adapter position of the target item or {@link RecyclerView#NO_POSITION} if no target view is

Returns the layout space change between the previous layout pass and current layout pass. <p> Make sure you call {@link #onLayoutComplete()} at the en

Returns true if the RecyclerView this LayoutManager is bound to has focus. @return True if the RecyclerView has focus, false otherwise. @see View#isF

Offsets all children's positions by the given amount. @param amount Value to add to each child's layout parameters

Called if the RecyclerView this LayoutManager is bound to has a different adapter set. The LayoutManager may use this opportunity to clear caches and

Called when the scroll position of this RecyclerView changes. Subclasses should use this method to respond to scrolling within the adapter's data set

Called by the RecyclerView before the layout begins. Item animator should record necessary information about the View before it is potentially rebound

Recycles the scrapped views. <p> When a view is detached and removed, it does not trigger a ViewGroup invalidate. This is the expected behavior if scr

Remove a child view and recycle it using the given Recycler. @param index Index of child to remove and recycle @param recycler Recycler to use to rec

Removes the specified Runnable from the message queue. <p> Calling this method when LayoutManager is not attached to a RecyclerView has no effect. @p

1.Recycle操作对应的是removeView, View被remove后调用Recycler的recycleViewHolderInternal回收其ViewHolder 2.Scrap操作对应的是detachView，View被detach后调用Reccyler的scrapView

Does not perform bounds checking. Used by internal methods that have already validated input. <p> It also reports any unused scroll request to the rel

Set the {@link LayoutManager} that this RecyclerView will use. <p>In contrast to other adapter-backed views such as {@link android.widget.ListView} o

Internal only: Sets the listener that must be called when the animator is finished animating the item (or immediately if no animation happens). This i

Sets the measured dimensions from the given bounding box of the children and the measurement specs that were passed into {@link RecyclerView#onMeasure

Sets the orientation of the layout. {@link android.support.v7.widget.LinearLayoutManager} will do its best to keep scroll position. @param orientatio

To be called only during {@link #onLayoutChildren(Recycler, State)} to add a view to the layout that is known to be going away, either because it has

Requests an an item to be prefetched, based on position, with a specified distance, indicating priority. @param layoutPosition Position of the item t

Prepares the ViewHolder to be removed/recycled, and inserts it into the RecycledViewPool. Pass false to dispatchRecycled for views that have not been

Called by the RecyclerView when an adapter item is present both before and after the layout and RecyclerView has received a {@link Adapter#notifyItemC

When an item is changed, ItemAnimator can decide whether it wants to re-use the same ViewHolder for animations or RecyclerView should create a copy of

Utility method for clearing holder's internal RecyclerView, if present

Temporarily detach a child view. <p>LayoutManagers may want to perform a lightweight detach operation to rearrange views currently attached to the Re