myeonginwoo

class MainViewModel(val view: MainView) {

    private var currentItem: Item by Delegates.observable(Item.ITEM_A,
        { _: KProperty<*>, oldItem: Item, newItem: Item ->
            view.onUpdatedItem(oldItem, newItem)
        })

    fun onClicked(item: Item) {
        currentItem = item
    }

myeonginwoo

class MainPresenter(val view: MainView) {

    private var currentItem: Item = Item.ITEM_A

    fun onClicked(item: Item) {
        view.onUpdatedItem(currentItem, item)
        currentItem = item
    }
}

myeonginwoo

enum class Item(val titleId: Int, val colorId: Int) {
    ITEM_A(R.string.a, R.color.red),
    ITEM_B(R.string.b, R.color.green),
    ITEM_C(R.string.c, R.color.blue),
    ITEM_D(R.string.d, R.color.black)
}

bt_d.setOnClickListener {
        mainPresenter.onClicked(Item.ITEM_D)
    }

myeonginwoo

class MainActivity : AppCompatActivity(), MainView {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val mainPresenter = MainPresenter(this)

        bt_a.setOnClickListener {
            mainPresenter.onClicked(Item.ITEM_A)
        }

myeonginwoo

class MainActivity : AppCompatActivity(), MainView {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val mainPresenter = MainPresenter(this)

        bt_a.setOnClickListener {
            mainPresenter.onClicked(ITEM_A)
        }

myeonginwoo

enum class Item(val titleId: Int, val colorId: Int) {
    ITEM_A(R.string.a, R.color.red),
    ITEM_B(R.string.b, R.color.green),
    ITEM_C(R.string.c, R.color.blue)
}

myeonginwoo

enum class Item {
    ITEM_A, ITEM_B, ITEM_C, ITEM_D
}

myeonginwoo

override fun onUpdatedItem(oldItem: Item, newItem: Item) {
    tv_item.text = "${getItemStr(oldItem)} -> ${getItemStr(newItem)}"
    iv_item.setBackgroundColor(ContextCompat.getColor(this, when (newItem) {
        ITEM_A -> R.color.red
        ITEM_B -> R.color.green
        ITEM_C -> R.color.blue
    }))
}

private fun getItemStr(item: Item): String = getString(when (item) {

myeonginwoo

override fun onUpdatedItem(oldItem: Int, newItem: Int) {
    tv_item.text = "${getItemStr(oldItem)} -> ${getItemStr(newItem)}"
    iv_item.setBackgroundColor(ContextCompat.getColor(this, when (newItem) {
        ITEM_A -> R.color.red
        ITEM_B -> R.color.green
        ITEM_C -> R.color.blue
        else -> throw  IllegalArgumentException("invalid item")
    }))
}

myeonginwoo

enum class Item {
    ITEM_A, ITEM_B, ITEM_C
}