jorgecasariego

class SmartPhone(
        val manufacture: String?,
        val model: String?,
        val storage: String?,
        val screenSize: String?) {

    data class Builder(
            var manufacture: String? = null,
            var model: String? = null,
            var storage: String? = null,

jorgecasariego

import java.util.*
import kotlin.properties.Delegates

interface ValueChangedListener {
    fun onValueChanged(newValue: String)
}

class PrintingTextChangedListener: ValueChangedListener {
    override fun onValueChanged(newValue: String) {
        println("Value of the text is: $newValue")

jorgecasariego

var text: String by Delegates.observable(
            initialValue = "",
            onChange = {
                property, oldValue, newValue ->
                listener.onValueChanged(newValue)
            }
    )

jorgecasariego

class MyFragment : Fragment() {
    private lateinit var viewModel: MyViewModel
    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProviders.of(this).get(MyViewModel::class.java)
    }
}

jorgecasariego

class MyViewModel : ViewModel() {

    // Stored cached bitmap.
    private var cachedBitmap: Bitmap? = null

    // Retrieves the image.
    fun getImage(): Bitmap {
        // If the image is not already cached, download it and cache it.
        if (cachedBitmap == null) {
            cachedBitmap = downloadImage()

jorgecasariego

class MainFragment : Fragment() {
    private lateinit var viewModel: MainViewModel
    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProviders.of(this).get(MainViewModel::class.java)
        imageView.setImageBitmap(viewModel.getImage())
    }

}

jorgecasariego

class MyViewModel : ViewModel() {
    val imageLiveData = MutableLiveData<Bitmap>()
    fun getImage() {
        // ...
    }
}

jorgecasariego

class MyFragment : Fragment() {
    private lateinit var viewModel: MainViewModel
    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        viewModel = ViewModelProviders.of(this).get(MainViewModel::class.java)

        // We observe the bitmap emitted from `imageLiveData` and
        // display it in the `ImageView`.
        viewModel.imageLiveData.observe(this, Observer {
            imageView.setImageBitmap(it)

jorgecasariego

class MyViewModel : ViewModel() {
    // Some image downloader class.
    val imageDownloader = ImageDownloader()
    val imageLiveData = MutableLiveData<Bitmap>()

    fun getImage() {
        // If we don't have a value already pushed to the live data
        // and the download is not in progress, start a new one.
        if (imageLiveData.value == null && !imageDownloader.isDownloading) {
            // This is just some sample API that uses RxJava, but

jorgecasariego

class ViewModel: ViewModel() {
   fun fetchDocs() {
       get("developer.android.com") { result ->
           show(result)
       }
    }
}