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How to implement a dynamic list view inside fragment android studio in Kotlin

I have two fragments that share information with each other, in the first one I have an edit text and button widget. The second fragment is just a listview. When the user clicks the button, it displays whatever is in the edit text widget in the second fragment.
So if the user enters the text study and clicks the button the second fragment will display
Study
If the user then enters the text eat and clicks the button, the second fragment will display
Study
Eat
I am having so issues with displaying the texts
So far this is what I have done
class FirstFragment : Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
viewModel = activity?.run { ViewModelProvider(this)[MyViewModel::class.java]
} ?: throw Exception("Invalid Activity")
val view = inflater.inflate(R.layout.one_fragment, container, false)
val button = view.findViewById<Button>(R.id.vbutton)
val value = view.findViewById<EditText>(R.id.textView)
button.setOnClickListener {
}
return view;
}
}
class SecondFragment : Fragment() {
lateinit var viewModel: MyViewModel
#SuppressLint("MissingInflatedId")
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
viewModel = activity?.run { ViewModelProvider(this)[MyViewModel::class.java]
} ?: throw Exception("Invalid Activity")
val view = inflater.inflate(R.layout.page3_fragment, container, false)
val valueView = v.findViewById<TextView>(R.id.textView)
return view
The problem I am having is how to display the texts

If I undestand you correctly, you want to share data between fragments? If yes, you can do that with "shared" viewModel. For example:
class FirstFragment : Fragment() {
private var _binding: FragmentFirstBinding? = null
private val binding get() = _binding!!
private val sharedViewModel by activityViewModels<SharedViewModel>()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentFirstBinding.inflate(inflater, container, false)
binding.buttonChangeFragment.setOnClickListener {
/*
You can change data here, or in navigateWithNavController() from
activity (You already have an instance of your viewModel in activity)
*/
sharedViewModel.changeData(binding.myEditText.text.toString())
if (requireActivity() is YourActivity)
(requireActivity() as YourActivity).navigateWithNavController()
}
return binding.root
}
}
class SecondFragment : Fragment() {
private var _binding: FragmentSecondBinding? = null
private val binding get() = _binding!!
private val sharedViewModel by activityViewModels<SharedViewModel>()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentSecondBinding.inflate(inflater, container, false)
binding.secondFragmentText.text = sharedViewModel.someData.value
return binding.root
}
}
and your activity:
class YourActivity: AppCompatActivity() {
private lateinit var binding: YourActivityBinding
private lateinit var appBarConfiguration: AppBarConfiguration
private val sharedViewModel: SharedViewModel by lazy {
ViewModelProvider(
this
)[SharedViewModel::class.java]
}
private lateinit var navController: NavController
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = YourActivityBinding.inflate(LayoutInflater.from(this))
setContentView(binding.root)
navController = this.findNavController(R.id.nav_host_fragment)
appBarConfiguration = AppBarConfiguration(navController.graph)
}
/*
This function is just for test
*/
fun navigateWithNavController() {
navController.navigate(R.id.secondFragment)
}
override fun onSupportNavigateUp(): Boolean {
return NavigationUI.navigateUp(navController, appBarConfiguration)
}
}
And your viewModel should look something like this:
class SharedViewModel : ViewModel() {
private val _someData = MutableLiveData("")
val someData: LiveData<String>
get() = _someData
fun changeData(newData: String?) {
_someData.value = newData ?: _someData.value
}
}

Your view model should have a backing list of the entered words. When a word is added, the list can be updated, and in turn you can update a LiveData that publishes the latest version of the list.
class MyViewModel: ViewModel() {
private val backingEntryList = mutableListOf<String>()
private val _entryListLiveData = MutableLiveData("")
val entryListLiveData : LiveData<String> get() = _entryListLiveData
fun addEntry(word: String) {
backingEntryList += word
_entryListLiveData.value = backingEntryList.toList() // use toList() to to get a safe copy
}
}
Your way of creating the shared view model is the hard way. The easy way is by using by activityViewModels().
I also suggest using the Fragment constructor that takes a layout argument, and then setting things up in onViewCreated instead of onCreateView. It's less boilerplate code to accomplish the same thing.
In the first fragment, you can add words when the button's clicked:
class FirstFragment : Fragment(R.layout.one_fragment) {
private val viewModel by activityViewModels<MyViewModel>()
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
val button = view.findViewById<Button>(R.id.vbutton)
val value = view.findViewById<EditText>(R.id.textView)
button.setOnClickListener {
viewModel.addEntry(value.text.toString())
}
}
}
In the second fragment, you observe the live data:
class SecondFragment : Fragment(R.layout.page3_fragment) {
private val viewModel by activityViewModels<MyViewModel>()
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
val valueView = view.findViewById<TextView>(R.id.textView)
viewModel.entryListLiveData.observe(viewLifecycleOwner) { entryList ->
valueView.text = entryList.joinToString(" ")
}
}
}

Change background color of a Fragment from DialogFragment ColorPicker using Mutablelivedata not working

My app should be able to change color of one part of my screen in a Fragment (called Color Preview) from Color Picker that is DialogFragment and appears once a Button is clicked. I used the same ViewModel with MutableLiveData in it within Fragment and DialogFragment. However I am not able to get Data about color in Fragment when I pick some color in DialogFragment. Code below.
Dialog Fragment:
class ColorFragment : DialogFragment() {
private var _binding: FragmentColorBinding? = null
private val binding get() = _binding!!
private val viewModel: MainViewModel by lazy {
getViewModel {
MainViewModel()
}
}
#SuppressLint("DialogFragmentInsteadOfSimpleDialog")
override fun onStart() {
super.onStart()
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
FragmentColorBinding.inflate(inflater, container, false).apply {
_binding = this
lifecycleOwner = this#ColorFragment
mainViewModel = getViewModel()
return root
}
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.color02.setOnClickListener {
viewModel.currentLightProfileColor.value = "#00ffff"
}
}
Main Fragment (where color should be shown) looks like this:
class MainFragment : Fragment() {
private var _binding: FragmentMainBinding? = null
private val binding get() = _binding!!
private var viewCreated = false
private val viewModel: MainViewModel by lazy {
getViewModel {
MainViewModel()
}
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
FragmentMainBinding.inflate(inflater, container, false).apply {
_binding = this
lifecycleOwner = this#MainFragment
mainViewModel = getViewModel()
executePendingBindings()
viewCreated = true
return root
}
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
binding.colorPreview.holder?.addCallback(this)
viewModel.currentLightProfileColor.observe(viewLifecycleOwner) { color ->
Color.parseColor(color.toString()).let { color ->
Timber.d("color LiveDataGet: ${color}")
binding.colorPreview.setBackgroundColor(color)
}
}
binding.color.setOnClickListener {
findNavController().navigate(R.id.ColorFragment)
}
}
In my ViewModel there is only MutableLiveData for color:
class MainViewModel : ViewModel() {
val currentLightProfileColor = MutableLiveData<String>()}
I dont get any errors but once I click on color2 I should get from Timber in Log: "color LiveDataGet: #00ffff" but I dont and color preview does not change color.
Did I miss something?
I would appreciate if someone could quickly take a look at my code. Thanks!

I found a solution. In Kotlin, data is not shared if viewModels() is instantiated without activityViewModels().
So I changed my code, instead of:
private val viewModel: MainViewModel by lazy {
getViewModel {
LightmvpViewModel()
}
}
I wrote:
private val viewModel: MainViewModel by activityViewModels()
With that simple change, everything should work.

Android ViewModel instantiate twice using hilt

I have a parent fragment which fetches a list from API using ViewModel and Retrofit, the ViewModel is injected with Hilt.
After the list gets fetched the parent fragment will pass to its child fragment that is inside of parent fragment.
but the problem is that ViewModel is instantiated one more time in the child fragment.
Parent Fragment
#AndroidEntryPoint
class ParentFragment : Fragment() {
override val mViewModel: URLViewModel by viewModels()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
mViewBinding = getViewBinding(inflater, container)
mViewModel.liveData.observe(this, { data ->
{
childFragmentManager.beginTransaction().apply {
replace(
mViewBinding.fragmentContainer.id,
ChildFragment(data)
)
}
commit()
} })
mViewModel.getURL("TEST", "2021-06-18", "2021-07-18", 1 , 0 , -1, false)
return mViewBinding.root
}
}
ChildFragment
#AndroidEntryPoint
class ChildFragment(val data: List<Item>) : Fragment() {
override val mViewModel: URLViewModel by viewModels()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
mViewBinding = getViewBinding(inflater, container)
// mViewModel is instantiated again and some all strings properties of it is null.
return mViewBinding.root
}
}
URLViewModel
#HiltViewModel
class URLViewModel #Inject constructor(private val urlApi: URLApi): ViewModel() {
private val _urlLiveData = MutableLiveData<State<Any?>>()
val urlLiveData: LiveData<State<Any?>> = _urlLiveData
var urlName: String? = null
var beginDate: String? = null
var endDate: String? = null
var adultCount = 0
var childrenCount = 0
var airportId = 0
var isRoundTrip = false
init {
Log.e("URLViewModel", "iniialed again" )
}
#ExperimentalStdlibApi
fun getUrl(urlName: String, beginDate: String, endDate: String, adultCount: Int, childCount: Int, airportId: Int, isRoundTrip: Boolean){
Log.e("XXXXXX", "getUrl: called with url of " + urlName )
this.urlName = urlName
this.beginDate = beginDate
this.endDate = endDate
this.adultCount = adultCount
this.childrenCount = childCount
this.airportId = airportId
this.isRoundTrip = isRoundTrip
val mutableLiveData = MutableLiveData<State<Any?>>()
mutableLiveData.value = State.loading()
viewModelScope.launch {
val res = urlApi.getURL(urlName,beginDate,endDate,adultCount,childCount,airportId,isRoundTrip)
Log.e("URLVIewModel", "getUrl: response received" )
_urlLiveData.value = res
}
}
}
when I wanna access some properties like beginDate, they are null, because the ViewModel is instantiated again,

viewModels() delegation create view model against the same instance i.e Fragment's instance in your case. What you need to do is to create a shared View model .
There is helper delegate available for it with ktx libraries.
add the ktx dependency which you already have i guess from here.
implementation "androidx.fragment:fragment-ktx:1.3.4"
And create view model with
private val viewModel by activityViewModels<UrlViewModel>()

You do not have to use activity shared view model. Simply request view model from parent fragment in ChildFragment.
private val viewModel by viewModels<UrlViewModel>(ownerProducer = { requireParentFragment() })

You are trying to use share viewmodel. Try to following code for reference.
#AndroidEntryPoint
class ParentFragment : Fragment() {
private lateinit var viewModel: URLViewModel
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = ViewModelProvider(requireActivity()).get(URLViewModel::class.java)
}
}
#AndroidEntryPoint
class ChildFragment : Fragment() {
private lateinit var viewModel: URLViewModel
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = ViewModelProvider(requireActivity()).get(URLViewModel::class.java)
}
}

Android Room ViewModel initialization in fragment crashes app

The situation is pretty straightforward. I have a simple android app with 4 fragments displayed through a bottom navigation bar, and a central Room database. Each fragment should be able to perform CRUD operations on the DB through a viewmodel (details are probably irrelevant but I'll show this as well to be sure):
class ViewModel(application: Application): AndroidViewModel(application) {
val readAllIngredients: LiveData<List<Ingredient>>
val readAllRecipes: LiveData<List<Recipe>>
private val ingredientRepository: IngredientRepository
private val recipeRepository: RecipeRepository
init {
val ingredientDAO = ShoppingAppDatabase.getDatabase(application).ingredientDAO()
val recipeDAO = ShoppingAppDatabase.getDatabase(application).recipeDAO()
ingredientRepository = IngredientRepository(ingredientDAO)
recipeRepository = RecipeRepository(recipeDAO)
readAllIngredients = ingredientRepository.allIngredients
readAllRecipes = recipeRepository.allRecipes
}
fun addIngredient(ingredient: Ingredient) {
viewModelScope.launch(Dispatchers.IO) {
ingredientRepository.put(ingredient)
}
}
fun deleteIngredient(ingredient: Ingredient) {
viewModelScope.launch(Dispatchers.IO) {
ingredientRepository.delete(ingredient)
}
}
fun addRecipe(recipe: Recipe) {
viewModelScope.launch(Dispatchers.IO) {
recipeRepository.put(recipe)
}
}
fun updateRecipe(recipe: Recipe) {
viewModelScope.launch(Dispatchers.IO) {
recipeRepository.update(recipe)
}
}
fun updateIngredient(ingredient: Ingredient) {
viewModelScope.launch(Dispatchers.IO) {
ingredientRepository.update(ingredient)
}
}
}
I'm initializing a viewmodel in each fragment, but with limited success. Here's a fragment for which everything works fine:
class InventoryFragment() : Fragment() {
private var listAdapter = IngredientAdapter()
private lateinit var viewModel : ViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_inventory, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
listAdapter = IngredientAdapter()
recycler_view.apply {
layoutManager = LinearLayoutManager(activity)
adapter = listAdapter
}
viewModel = ViewModelProvider(this).get(ViewModel::class.java)
viewModel.readAllIngredients.observe(viewLifecycleOwner, Observer { ingredient -> listAdapter.setData(ingredient) })
add_button.setOnClickListener{
val errorMessages = validateInput()
if(errorMessages.isNotEmpty()) {
displayToast(activity, errorMessages)
}
else {
viewModel.addIngredient(Ingredient(
edit_name.text.toString(),
edit_qty.text.toString().toFloat(),
edit_um.text.toString()
))
listAdapter.notifyDataSetChanged()
displayToast(activity, "Ingredient added")
hideKeyboard(activity, requireView().windowToken)
}
clearInput()
}
}
}
I'm initializing it in the onViewCreated callback and yeah, it works fine. Doing the same thing in a different fragment yields.. different results for some reason.
class BrowseFragment() : Fragment() {
private lateinit var viewModel: ViewModel
var recipeAdapter = RecipeAdapter()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_browse, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = ViewModelProvider(this).get(ViewModel::class.java)
viewModel.readAllRecipes.observe(viewLifecycleOwner, Observer { recipe -> recipeAdapter.setData(recipe) })
submit_button.setOnClickListener{
var submitFragment = SubmitFragment(recipeAdapter)
var tr = (view.context as FragmentActivity).supportFragmentManager.beginTransaction()
tr.replace(R.id.fragment_container, submitFragment)
tr.commit()
}
browse_recycler_view.apply {
layoutManager = LinearLayoutManager(activity)
adapter = recipeAdapter
}
}
}
When I try to initialize the viewmodel in onViewCreated, I get an IllegalStateException: Can't access ViewModels from detached fragment exception. Creating it in onCreate doesn't work either, since the lifecycle owner is null, which makes sense I guess. What exactly am I doing wrong here?

how to initialize viewmodel in activity using dagger?

I'm dev-ing activity using dagger. In my fragment, I can use this code as below. but when I use this code in activity, I cannot use this code.
private val viewModel by viewModels<NoticeViewModel> { viewModelFactory }
As result I can't initialize viewmodel. how can I initialize activity using dagger?
fragment
class NoticeFragment : DaggerFragment() {
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
private val viewModel by viewModels<NoticeViewModel> { viewModelFactory }
private lateinit var viewDataBinding: FragmentNoticeBinding
private var notice = ""
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val view = inflater.inflate(R.layout.fragment_notice, container, false)
viewDataBinding = FragmentNoticeBinding.inflate(inflater, container, false).apply {
viewmodel = viewModel
}
return view
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewDataBinding.lifecycleOwner = this.viewLifecycleOwner
init()
viewModel.getNotice()
}
private fun init(){
viewModel.notice.observe(this, Observer{
noticeMain.text = it
})
}
}
activity
class ScheduleDialog : DaggerActivity() {
#Inject
lateinit var viewModelFactory: ViewModelProvider.Factory
private val viewModel by viewModels<ScheduleDialogViewModel> { viewModelFactory }
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_schedule_dialog)
//viewDataBinding = DataBindingUtil.setContentView( this,R.layout.activity_schedule_dialog)
viewModel.getScheduleById(5)
}
}

MyComponent component = DaggerMyComponent.builder().build();
component.inject(this);
For dependency injection you should have the following code, also in the component code should be
void inject(YourActivity activity);