DBFLOW and FlowCursor with Flexibleadapter

[carmas123]

Hi I use in my app (write with Kotlin) DBFlow lib. Now I want to use your lib to add more functionality but I have a problem. How can I use your adapter with a flow list? Flow list is very good on device with low performance and with more than 10k items.

[davideas]

Hello @carmas123, thanks for the message.
I need to look into it, I need more information and time, actually I can't tell you.

[carmas123]

Simply the FlowCursorList get from the cursor the data only when it is needed and not for all items, but it know how many items are. (getCount)

[davideas]

@carmas123, maybe you can use the onLoadMore feature.

[carmas123]

Oh yes this can be a solution, but it is not very simple, because I need to extract the first N items from DB and initialize the adapter and after that with same query I need to load other items.

[carmas123]

Please can you add a param to execute or not initializeItem().
I made a custom LazyList that load items from Array when it's required or displayed into recyclerview, but into "initializeItems" method all items a get from the array. Please can you bypass this method when no one expandable items.

You can add a method to disable this initialization.

[davideas]

@carmas123, loading hundreds or thousands items, it's much better doing with the OnLoadMore. But it depends of which items we are talking about.

Regarding the item initialization parameter, I think we can add it. I will check later what is the effect if items are not initialized. This has a strong impact for expandable items.

[davideas]

@carmas123, what do you think about these names: setInitiallyExpandItemsAtStartUp(boolean) or doNotExpandItemsAtStartUp(boolean) ? the latter has an impact for the rotation, the former actually never expands items at startUp, so it must be called by the user, if called it initializes and expands items to be expanded and so I can remove it from the constructor.

[carmas123]

Oh yes this is very good for me.
About the hundreds or thousands items...what you say it's true but if I use my lazy list it's have no impact with the performance. I post my code (write in Kotlin) to know how it work:

class LazyList<T>(cursor: FlowCursorList<AbstractModel>, creator: LazyList.ItemFactory<T>) : ArrayList<T?>() {

    // Chiudo il cursore corrente
    var mCursor: FlowCursorList<AbstractModel> = cursor
        set(cursor) {
            closeCursor()
            this.mCursor = cursor
        }

    private val mCreator: ItemFactory<T>

    init {
        mCreator = creator
    }

    override fun get(index: Int): T? {
        val size = super.size
        if (index < size) {
            // find item in the collection
            var item = super.get(index)
            if (item == null) {
                item = mCreator.create(mCursor, index)
                set(index, item)
            }
            return item
        } else {
            // we have to grow the collection
            for (i in size..index - 1) {
                add(null)
            }
            // create last object, add and return
            val item = mCreator.create(mCursor, index)
            add(item)
            return item
        }
    }

    override val size: Int
        get() = mCursor.getCount()

    fun closeCursor() {
        mCursor.close()
    }

    interface ItemFactory<T> {
        fun create(cursor: FlowCursorList<AbstractModel>, index: Int): T
    }
}

everything you need is a class that implement ItemFactory interface and all is done with a lazy item creation. This have only a problem!! That the result is an ArrayList and need to be casted to a mutable list.

[carmas123]

Unfortunately I had to leave this library...

[carmas123]

I tried to use onLoadMore functionality but the problem is when I try to use fast scroll or a custom index with alphabet. With onloadmore I don't do that. This is the majior problem

[carmas123]

Please can you push a commit with this changes or I need to fork this project?

[davideas]

I will push.

[carmas123]

Thank you so much