MinaSamy

class SecondFragment: Fragment() {

	private lateinit var viewModel: DemoViewModel

	override fun onCreate(savedInstanceState: Bundle ? ) {
		super.onCreate(savedInstanceState)
		viewModel = ViewModelProviders.of(activity).get(DemoViewModel::class.java)
	}

	override fun onCreateView(inflater: LayoutInflater, container: ViewGroup ? , savedInstanceState: Bundle ? ) : View ? {

MinaSamy

class MainFragment: Fragment() {

	private lateinitvar viewModel: DemoViewModel

	var buttonListener: OnSecondFragmentButtonClickListener ? =null

	override fun onCreate(savedInstanceState: Bundle ? ) {
		super.onCreate(savedInstanceState)
		viewModel = ViewModelProviders.of(activity).get(DemoViewModel::class.java)
	}

MinaSamy

class MainActivity: AppCompatActivity() {

	override fun onCreate(savedInstanceState: Bundle ? ) {
		super.onCreate(savedInstanceState)
		setContentView(R.layout.activity_main)

		val textViewNumbers = findViewById < TextView > (R.id.text_view_numbers)

		val viewModel = ViewModelProviders.of(this).get(DemoViewModel::class.java)
		viewModel.numbersLiveData.observe(this, object: Observer < List < Int >> {

MinaSamy

class DemoViewModel: ViewModel() {
	private val numbers = mutableListOf < Int > ()

	private val _numbersLiveDate = MutableLiveData < List < Int >> ()

	val numbersLiveData: LiveData < List < Int >> get() {
		if (_numbersLiveDate.value == null) {
			loadInitialData()
		}
		return _numbersLiveDate

MinaSamy

override fun onStop() {
	super.onStop()
	dataSource.addItem()
}

MinaSamy

class DemoDataSourceObserverTest {

	@get: Rule
	var rule: TestRule = InstantTaskExecutorRule()

	@Mock lateinit var observer: Observer < List < Int >> @Mock lateinit
	var lifeCycleOwner: LifecycleOwner

	lateinit var lifeCycle: LifecycleRegistry
	val dataSource = DemoDataSource()

MinaSamy

class DemoDataSourceTest {@get: Rule
	var rule: TestRule = InstantTaskExecutorRule()

	@Test
	fun shouldLoadData() {
		val dataSource = DemoDataSource()
		dataSource.loadNumbers()
		assertEquals(listOf(1, 2, 3, 4), dataSource.numberLiveData.value)
	}

MinaSamy

@Test
fun shouldLoadData() {
	val dataSource = DemoDataSource()
	dataSource.loadNumbers()
	assertEquals(listOf(1, 2, 3, 4), dataSource.numberLiveData.value)
}

MinaSamy

val source1 = MutableLiveData<Int>()
val source2 = MutableLiveData<Int>()

val merger = MediatorLiveData<Int>()
merger.addSource(source1, { number -> merger.postValue(number) })
merger.addSource(source2, { number -> merger.postValue(number) })

merger.observe(this, object : Observer<Int> {
            override fun onChanged(number: Int?) {
                Log.i("Merger", number.toString())

MinaSamy

val sumLiveData = Transformations.switchMap(dataSource.numberLiveData, {
	numbers - >MutableLiveData < Int > ().apply {
		postValue(numbers.sum())
	}
})

sumLiveData.observe(this, object: Observer < Int > {
	override fun onChanged(sum: Int ? ) {
		Log.i("Sum", sum.toString())
	}