This class is the contract between ItemTouchHelper and your application. It lets you control which touch behaviors are enabled per each ViewHolder and also receive callbacks when user performs these actions.
To control which actions user can take on each view, you should override
getMovementFlags(RecyclerView, ViewHolder) and return appropriate set
of direction flags. (
ItemTouchHelper.DOWN). You can use
makeMovementFlags(int, int) to easily construct it. Alternatively, you can use
If user drags an item, ItemTouchHelper will call
onMove(recyclerView, dragged, target).
Upon receiving this callback, you should move the item from the old position
dragged.getAdapterPosition()) to new position (
in your adapter and also call
To control where a View can be dropped, you can override
canDropOver(RecyclerView, ViewHolder, ViewHolder). When a
dragging View overlaps multiple other views, Callback chooses the closest View with which
dragged View might have changed positions. Although this approach works for many use cases,
if you have a custom LayoutManager, you can override
chooseDropTarget(ViewHolder, java.util.List, int, int) to select a
custom drop target.
When a View is swiped, ItemTouchHelper animates it until it goes out of bounds, then calls
onSwiped(ViewHolder, int). At this point, you should update your
adapter (e.g. remove the item) and call related Adapter#notify event.
Return true if the current ViewHolder can be dropped over the the target ViewHolder.