ItemChangeList.kt

class ItemChangedList<T> : ArrayList<T>() {
    private val _changedObserverList = ArrayList<OnPropertyChangedObserver>()

    val isReadOnly: Boolean
        get() = false

    override fun add(element: T): Boolean {
        sendPropertyChanged(element, ITEM_ADDED)
        return super.add(element)
    }

    override fun iterator(): MutableIterator<T> {
        return super.iterator()
    }

    override fun clear() {
        for (item in this) {
            sendPropertyChanged(item, ITEM_REMOVED)
        }
        super.clear()
    }

    override operator fun contains(element: T): Boolean {
        return super.contains(element)
    }

    override fun remove(element: T): Boolean {
        sendPropertyChanged(element, ITEM_REMOVED)
        return super.remove(element)
    }

    override fun indexOf(element: T): Int {
        return super.indexOf(element)
    }

    override fun get(index: Int): T {
        return super.get(index)
    }

    override fun set(index: Int, element: T): T {
        return super.set(index, element)
    }

    override fun removeAt(index: Int): T {
        return super.removeAt(index)
    }

    fun copyTo(array: Array<T>, arrayIndex: Int) {
        addAll(array.toList().drop(arrayIndex))
    }

    fun count(): Int {
        return super.size
    }

    fun insert(index: Int, item: T) {
        sendPropertyChanged(item, ITEM_ADDED)
        super.add(index, item)
    }

    fun addObserver(observer: OnPropertyChangedObserver) {
        _changedObserverList.add(observer)
    }

    fun removeObserver(observer: OnPropertyChangedObserver) {
        _changedObserverList.remove(observer)
    }

    fun clearObserver() {
        _changedObserverList.clear()
    }

    private fun sendPropertyChanged(item: Any?, args: String) {
        for (observer in _changedObserverList) {
            observer.onChanged(item, args)
        }
    }

    interface OnPropertyChangedObserver {
        fun onChanged(item: Any?, args: String)
    }

    companion object {
        const val ITEM_ADDED = "bbed36af-0b7b-4e53-abc9-02d6a14d7f34"
        const val ITEM_REMOVED = "7390116e-586d-4e62-9343-5b82b0a8c6c5"
    }
}