Store new position of RecyclerView items in SQLite after being dragged and dropped

Question

I have a two dimensional ArrayList of type String which is the input to the adapter class of the RecyclerView. The data in the list is

Answer 1

You need a field in each DB row for storing the order. Then you need to implements those features:

• On new row insert (when you insert a new object in database) you need to set the order field to the next int. You can get the current max value (with sql function MAX) and then simply do +1

• When user move an item in RecyclerView, in method onMovedyou must update all other rows. You can use the fromPos and toPos for that. More on that below

• When you fill your RecyclerView with data you need to order them by order field

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Explanation of 2nd feature to be implemented: basically you need to update all rows with order between fromPos and toPos:

• if user moved the item up (for example from position 4 to 2), you need to:

  1. get primary key field of current item (using position 4)
  2. change all rows between order 2 and order 4: so change 2 -> 3 and 3 -> 4
  3. Change current item order (using primary key of first point) to toPos: in this example change current item order to 2

• if user moved the item down (for example from position 2 to 4) you need to:

  1. get primary key field of current item (using position 2)
  2. change all rows between order 2 and order 4: so change 4 -> 3 and 3 -> 2
  3. change current item order (using primary key of first point) to toPos: in this example change current item order to 4

Hope it helps a little