this is the code for expanding/collapsing an item. how can I Expand all items in a recycler view with a single button click?

 private fun expandParentRow(position: Int){ \\to expand an item
            val currentBoardingRow = list[position]
            val services = currentBoardingRow.gameDetes
            currentBoardingRow.isExpanded = true
            var nextPosition = position
            if(currentBoardingRow.type == Constants.PARENT) {
                services?.forEach { service ->
                    val parentModel = IndividualReport()
                    parentModel.type = Constants.CHILD
                    val subList: ArrayList<GameDete> = ArrayList()
                    subList.add(service)
                    parentModel.gameDetes = subList
                    list.add(  nextPosition, parentModel)
                }
                notifyDataSetChanged()
            }
    }

    private fun collapseParentRow(position: Int){ \\ to collapse an item
        val currentBoardingRow = list[position]
        val services = currentBoardingRow.gameDetes
        list[position].isExpanded = false
        if(list[position].type==Constants.PARENT){
            services?.forEach { _ ->
                list.removeAt(position   1)
            }
            notifyDataSetChanged()
        }
    }

CodePudding user response：

Just simply do a forEach or a for loop to iterate all items of the recycle view, set the .isExpanded to true and finally call notifyDataSetChanged().

For example:

fun expandAllItems() {
    val currentList = list.map { it.copy() }

    currentList.forEachIndexed { index, item -> 
        item.isExpanded = true

        val services = item.gameDetes

        if(item.type == Constants.PARENT) {
            services?.forEach { service ->
                val parentModel = IndividualReport()
                parentModel.type = Constants.CHILD
                val subList: ArrayList<GameDete> = ArrayList()
                subList.add(service)
                parentModel.gameDetes = subList
                list.add(  index, parentModel)
            }
        }
    }
    notifyDataSetChanged()
}

This should do the job.

CodePudding user response：

you can expand with animation (new animate() api) with this code block:

private fun RecyclerView.showAnimation(
    duration: Long,
    startFrom: Int = 0,
    itemsDelay: Long = 50,
    fromAlpha: Float = 1.0f,
    toAlpha: Float = 1.0f,
    fromScaleY: Float = 1.0f,
    toScaleY: Float = 1.0f,
    onAnimationStart: () -> Unit = {},
    onAnimationEnd: () -> Unit = {}
) {
    viewTreeObserver.addOnPreDrawListener(
        object : ViewTreeObserver.OnPreDrawListener {
            override fun onPreDraw(): Boolean {
                viewTreeObserver.removeOnPreDrawListener(this)
                for (i in startFrom until childCount) {
                    val v: View = getChildAt(i)
                    v.alpha = fromAlpha
                    v.scaleY = fromScaleY
                    v.pivotY = 0f
                    v.animate().apply {
                        scaleY(toScaleY)
                        alpha(toAlpha)
                        setDuration(duration)
                        startDelay = (i * itemsDelay)
                        withStartAction(onAnimationStart)
                        withEndAction(onAnimationEnd)
                        start()
                    }
                }
                return true
            }
        })
}