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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.

Kotlin RecyclerView + fragment add retrofit2 response from api, with Drawer menu

I'm updating my knowledge of Android, and I want to make an app with a Drawer menu, call an api and display the values inside a fragment. Starting from the template created by android studio itself, I have followed this tutorial:https://howtodoandroid.com/mvvm-retrofit-recyclerview-kotlin/ but I have a problem when programming the MainActivity.
Android studio template create this fragment (only changes the name of fragments):
class CheckListFragment : Fragment() {
private var _binding: FragmentCheckListBinding? = null
// This property is only valid between onCreateView and
// onDestroyView.
private val binding get() = _binding!!
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
val checklistViewModel =
ViewModelProvider(this).get(CheckListViewModel::class.java)
_binding = FragmentCheckListBinding.inflate(inflater, container, false)
val root: View = binding.root
val textView: TextView = binding.textChecklist
checklistViewModel.text.observe(viewLifecycleOwner) {
textView.text = it
}
return root
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
The issue is that I don't know how I should call the viewmodel in that section, since I've tried in different ways, reading and reading examples, but none is exactly what I need. If you need me to show more parts of the code (viewmodel, viewmodelfactory etc. I can add it without any problem, although they are practically the same as those described in the tutorial)
In that example, in the MainActivity class we have this:
class MainActivity : AppCompatActivity() {
private val TAG = "MainActivity"
private lateinit var binding: ActivityMainBinding
lateinit var viewModel: MainViewModel
private val retrofitService = RetrofitService.getInstance()
val adapter = MainAdapter()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
viewModel = ViewModelProvider(this, MyViewModelFactory(MainRepository(retrofitService))).get(MainViewModel::class.java)
binding.recyclerview.adapter = adapter
viewModel.movieList.observe(this, Observer {
Log.d(TAG, "onCreate: $it")
adapter.setMovieList(it)
})
viewModel.errorMessage.observe(this, Observer {
})
viewModel.getAllMovies()
}
But here not use fragments.
I would greatly appreciate help, or a link where I can see an example of this

How to set MainViewModel?

I have my MainActivity where there are the movie with their poster. If I click on a poster (in the layout there are 4 ImageView) I can read the plot (a TextView) that is in the Fragment. If I open my app with the emulator MainActivity and Fragment are overlapping so I need to set the ViewModel. How to set it?
//MainActivity
class JacksonActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.jackson_activity)
if (savedInstanceState == null) {
supportFragmentManager.beginTransaction()
.replace(R.id.jackson_film, JacksonFragment.newInstance())
.commitNow()
}
}
//Fragment
class JacksonFragment : Fragment() {
companion object {
fun newInstance() = JacksonFragment()
}
private lateinit var viewModel: MainViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?,
): View {
return inflater.inflate(R.layout.jackson_fragment, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewModel = ViewModelProvider(this)[MainViewModel::class.java]
// TODO: Use the ViewModel
} }

ViewModelProvider is deprecated. more info: ViewModelProvider
To implement viewModel simply use val viewModel: MainViewModel by viewmodels()
if you use the same viewmodel in more than one place(acitity/fragment) in fragment use val viewModel: MainViewModel by activityViewModels()
Note: do not forget to update the dependencies. More info: ViewModel / SharedViewModel

LiveData + ViewModel States , values clash and only last value is observed

Im using ViewModel with states and LiveData with one observer .
I have an activity and a fragment . everything works fine until Im rotating the screen
and then, the states I want to observe , clash.
What can I do in order to prevent it and make it work as expected?
I know I can add more observers but I don't want to solve it in this way , it may lead to problems with the other code.
MainActivity code :
private var appsDetailsHmap = HashMap< String , AppsDetails>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
progressBar = CircleProgressBarDialog(this)
viewModel.getState().observe(this, Observer {state->
when(state){
is SettingsViewModelStates.GetAppsDetails->initUI(state.list)
is SettingsViewModelStates.ShowDialog->progressBar.showOrHide(state.visibility)
is SettingsViewModelStates.GetCachedData->setCachedSettings(state.appDetailsHmap,state.selectedApp,state.speechResultAppName)
}
})
if (savedInstanceState==null){
viewModel.initSettingsActivityUI(appsDetailsHmap)
}
else{
viewModel.initCachedSettingsActivityUI()
}
Fragment code
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val view= inflater.inflate(R.layout.fragment_added_apps, container, false)
viewModel.getCachedApplist()
return view
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel.getState().observe(viewLifecycleOwner, Observer {state->
when(state){
is SettingsViewModelStates.PassAppsToFragment->{
initRecyclerView(state.list)
}
}
})
}
ViewModel
private var state=MutableLiveData<SettingsViewModelStates>()
private var appsDetailsHmap=HashMap<String,AppsDetails>()
private var addedApps= HashMap<String,Drawable?>()
fun getState()=state as LiveData<SettingsViewModelStates>
fun getCachedApplist(){
if (addedApps.isEmpty()){
getAppsList()
println("empty")
}
else
state.setValue(SettingsViewModelStates.PassAppsToFragment(addedApps))
}
fun initCachedSettingsActivityUI(){
state.setValue(SettingsViewModelStates.GetCachedData(appsDetailsHmap,selectedApp,speechResultAppName))
}
fun initSettingsActivityUI(list:HashMap<String, AppsDetails>) {
appsDetailsHmap=list
state.setValue( SettingsViewModelStates.GetAppsDetails(list))
}
states:
sealed class SettingsViewModelStates {
data class GetAppsDetails(val list:HashMap<String, AppsDetails>):SettingsViewModelStates()
data class ShowDialog(val visibility: Int) : SettingsViewModelStates()
data class PassAppsToFragment(val list:HashMap<String,Drawable?>) : SettingsViewModelStates()
data class GetCachedData(val appDetailsHmap:HashMap<String,AppsDetails>,
val selectedApp: AppsDetails,
val speechResultAppName:String ) : SettingsViewModelStates()
}