Develop Reference

Change MaterialToolbar title from Fragment - Kotlin

I have implemented a MaterialToolbar and I want to change the title and functionality of the buttons, depending on which fragment is active. But I've been trying for two days and I can't get access to toolbar from fragment.
It doesn't work with any option:
activity?.actionBar?.title
(activity as AppCompatActivity).supportActionBar?.title
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".view.MainActivity">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.appbar.MaterialToolbar
android:id="#+id/materialToolbar"
style="#style/Widget.MaterialComponents.Toolbar.Primary"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navigationIcon="#drawable/ic_menu" />
<fragment
android:id="#+id/fragmentContainer"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="0dp"
app:defaultNavHost="true"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/materialToolbar"
app:navGraph="#navigation/nav_graph" />
</androidx.constraintlayout.widget.ConstraintLayout>
<com.google.android.material.navigation.NavigationView
android:id="#+id/navigationView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="#color/primary_ultra_light"
app:headerLayout="#layout/header_menu_drawer"
app:menu="#menu/menu_drawer" />
</androidx.drawerlayout.widget.DrawerLayout>
MainActivity.kt
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
setSupportActionBar(binding.materialToolbar)
supportActionBar?.title = "Test"
}
}
HomeFragment.kt
class HomeFragment: Fragment() {
private lateinit var binding: HomeFragmentBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
activity?.actionBar?.title = "Home 1" /* actionBar == null */
/* supportActionBar == null */
(activity as AppCompatActivity).supportActionBar?.title = "Home 2"
}
Result of the code that does not comply with the expected
The idea is to remove the top block of the fragment (Calculators) and use the Toolbar (Test). For this I need to be able to adapt the toolbar for each fragment.
Possible solution <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
So far I have solved it with a ViewModel observer. I don't know if it's a correct solution, but it works. Any comment is welcome, both to confirm that it is a valid solution and if it is not.
ToolbarVM.kt
class ToolbarVM(app: Application) : AndroidViewModel(app) {
private val _title = MutableLiveData<String>()
var title: LiveData<String> = _title
fun setTitle(newTitle: String){
_title.value = newTitle
}
}
MainActivity.kt
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private val toolbarVm: ToolbarVM by viewModels()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
setSupportActionBar(binding.materialToolbar)
val titleObserver = Observer<String> { newTitle ->
binding.materialToolbar.title = newTitle
}
toolbarVm.title.observe(this, titleObserver)
}
}
HomeFragment
/*You have to instantiate the ToolbarVm and call the setTitle() method*/
private lateinit var toolbarVm: ToolbarVM
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
toolbarVm = activity?.let { ViewModelProvider(it)[ToolbarVM::class.java] }!!
}
// Call the method where necessary
toolbarVm.setTitle("Calculators")

From the MainActivity you can directly use:
binding.materialToolbar.title = "Test"
while when calling from a fragment, you can do the following:
activity?.findViewById<Toolbar>(R.id.materialToolbar)?.title = "Test"

I have solved it thanks to Razvan's answer. It works if I call it from the onViewCreated() function, but it doesn't work the first time the default fragment is loaded with navGraph. So I have placed it in onResume()
HomeFragment.kt
override fun onResume() {
super.onResume()
(activity as AppCompatActivity).supportActionBar?.title = getString(R.string.calculators)
}

On Click event Does not working with Data Binding in Android Studio

I am learning DataBinding in android studio. But I am facing a problem with binding a ModelView. I want to bind a function with a button on click event. I set a function in the model view. I want to update my text view with on click event of my button. But When I click the button my text is not updating. I can not understand what I have done wrong.
XML layout:
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable
name="model"
type="com.example.jetpack.MainModelView" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="#+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#{model.title}"
android:textSize="28sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:text="Update Text"
android:onClick="#{()-> model.update()}"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tv" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
Main Model View:
class MainModelView : ViewModel() {
var title: String = " This is My Application"
fun update() {
title = "I am Changed"
Log.d("UPDATE", "update successfully from main model view")
}
}
Main Activity:
class MainActivity : AppCompatActivity() {
lateinit var binding: ActivityMainBinding
lateinit var mainModelView: MainModelView
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
mainModelView = ViewModelProvider(this).get(MainModelView::class.java)
binding.model = mainModelView
}
}
My app Image:
thanks in advance for helping.

The title variable in ViewModel needs to be a ObservableField or LiveData otherwise you xml will never know when it's value got updated –
class MainViewModel : ViewModel() {
var text = MutableLiveData(" Welcome to my application ")
fun updateText() {
text.value = " Text is updated successfully "
}
}
class MainActivity : AppCompatActivity() {
lateinit var binding: ActivityMainBinding
lateinit var mainViewModel: MainViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
// Creating MainViewModel object
mainViewModel = MainViewModel()
// Binding mainViewModel variable
// with MainViewModel object
binding.mainViewModel = mainViewModel
// passing LifeCycleOwner to binding object
binding.lifecycleOwner = this
}
}

Room livedata , databinding issue : UI doesn't update when data changes

I am now developing an application where I use MVVM pattern for UI and repository interaction. In other words, I receive live data object with a list of models from my ROOM data base query via repository, then assign it to my live data variable in viewmodel. After that, this data should be populated to my xml layout recycler view via data binding, but It happens only once fragment is initialised. In other cases recycler view is void
DAO code :
#Query("SELECT * FROM note WHERE content LIKE :query ORDER BY isStarred")
fun searchAllNotes(query : String?) : Flow<List<Note>>
ViewModel code:
#HiltViewModel
class HomeViewModel #Inject constructor (
private val noteRepository : NoteRepository
) : ViewModel() {
private var _notesLiveData : LiveData<List<Note>> = noteRepository.getAllNotes().asLiveData()
val notesLiveData get()= _notesLiveData
fun searchNotes(query : String){
viewModelScope.launch(Dispatchers.IO){
_notesLiveData = noteRepository.searchAllNotes(query).asLiveData()
}
}
fun deleteNote(note : Note){
viewModelScope.launch(Dispatchers.IO){
noteRepository.deleteNote(note)
}
}
fun updateNoteChecked(note : Note){
viewModelScope.launch(Dispatchers.IO){
noteRepository.updateNoteChecked(note.id, note.isStarred)
}
}
Fragment code
#AndroidEntryPoint
class HomeFragment : Fragment(),
NoteCardAdapter.NoteTouchListener,
SearchView.OnQueryTextListener{
private var _binding : FragmentHomeBinding? = null
val binding get() = _binding!!
private val adapter by lazy {
NoteCardAdapter(this as NoteCardAdapter.NoteTouchListener)
}
private val vm : HomeViewModel by viewModels()
private val noteSharedViewModel : NoteSharedViewModel by activityViewModels()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentHomeBinding.inflate(inflater)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
binding.adapter = adapter
binding.vm = vm
binding.apply {
lifecycleOwner = viewLifecycleOwner
homeRecyclerView.isNestedScrollingEnabled = false
homeRecyclerView.layoutManager = LinearLayoutManager(view.context)
homeRecyclerView.itemAnimator= NotesItemAnimator()
}
binding.homeSearchView.isSubmitButtonEnabled = true
binding.homeSearchView.setOnQueryTextListener(this as SearchView.OnQueryTextListener)
binding.addNoteButton.setOnClickListener{
val note = Note(
"","","",false, activity?.getDate(), folderId = -1
)
noteSharedViewModel.selectNote(note)
val action = HomeFragmentDirections.actionHomeFragmentToSingleNoteFragment(
isNew = true
)
findNavController().navigate(action)
}
binding.foldersButton.setOnClickListener{
findNavController().navigate(HomeFragmentDirections.actionHomeFragmentToFoldersFragment())
}
}
xml layout code :
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
>
<data>
<variable
name="vm"
type="com.example.leonidsnotesapplication.presentation.notes_feature.viewmodels.HomeViewModel" />
<variable
name="adapter"
type="com.example.leonidsnotesapplication.presentation.notes_feature.adapters.NoteCardAdapter" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:background="#color/note_background_color_3"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".presentation.notes_feature.fragments.HomeFragment">
<androidx.appcompat.widget.SearchView
android:id="#+id/homeSearchView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="10dp"
android:theme="#style/AppSearchView"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintStart_toStartOf="parent"/>
<TextView
android:id="#+id/tvRecentTitle"
android:textStyle="bold"
android:textSize="25sp"
android:textColor="#color/button_color_2"
android:text="#string/recent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:layout_marginStart="20dp"
app:layout_constraintTop_toBottomOf="#id/homeSearchView"
app:layout_constraintStart_toStartOf="parent"/>
<ImageView
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_marginStart="16dp"
android:layout_marginTop="28dp"
android:background="#drawable/ic_circle_arrow"
app:layout_constraintStart_toEndOf="#id/tvRecentTitle"
app:layout_constraintTop_toBottomOf="#id/homeSearchView" />
<androidx.recyclerview.widget.RecyclerView
tools:listitem="#layout/note_card_view"
android:scrollbars="vertical"
android:scrollbarStyle="outsideInset"
android:id="#+id/homeRecyclerView"
android:layout_width="match_parent"
android:requiresFadingEdge="vertical"
android:fadingEdge="vertical"
android:fadingEdgeLength="15dp"
android:layout_height="500dp"
android:layout_marginTop="30dp"
app:setNoteAdapter="#{adapter}"
app:submitNoteList="#{vm.notesLiveData}"
app:layout_constraintTop_toBottomOf="#id/tvRecentTitle"
app:layout_constraintStart_toStartOf="parent"
/>
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:backgroundTint="#color/button_color_1"
android:id="#+id/add_note_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="16dp"
android:src="#drawable/ic_create"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:backgroundTint="#color/button_color_1"
android:id="#+id/folders_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="16dp"
android:src="#drawable/ic_folders_stack"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
Data binding adapter :
#BindingAdapter("submitNoteList")
fun submitNoteList(recyclerView: RecyclerView, data : List<Note>?){
val adapter = recyclerView.adapter as NoteCardAdapter
adapter.setData((data as ArrayList<Note>? ?: arrayListOf()))
}
#BindingAdapter("setNoteAdapter")
fun setNoteAdapter(recyclerView: RecyclerView, adapter: NoteCardAdapter){
adapter.let {
recyclerView.adapter = it
}
}

You should observe your live data. Example code is:
vm.notesLiveData.observe(viewLifecycleOwner) { adapter.submitList(it) }

How to pass multiple views as parameters in BindingAdapter in Data binding android?

I have one relative layout and one ImageView. I want to set visibility based on Image loading like if image loads successfully then imageview is visible and if some error occurs relative layout is visible. How can I manage this scenario in data binding using BindingAdapter ?

Your question is not clear so I don't know if it will help you.
These are steps to implement
1: Create parameters in BindingAdapter.kt
#BindingAdapter("showLoading")
fun View.showLoading(loading: Boolean) {
if (loading) {
visible()
} else {
gone()
}
}
#BindingAdapter("showError")
fun View.showError(error: Boolean) {
if (error) {
visible()
} else {
gone()
}
}
fun View.gone() {
this.visibility = View.GONE
}
fun View.visible() {
this.visibility = View.VISIBLE
}
2: Use parameters [app:showLoading="#{viewModel.showLoading}"] and [app:showError="#{viewModel.showError}"] created in file XML
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
<variable
name="viewModel"
type="com.xxx.xxx.MainViewModel" />
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#EAEAE2"
android:orientation="vertical">
<Button
android:id="#+id/btnAdd"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ShowLoading" />
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:showLoading="#{viewModel.showLoading}" />
<RelativeLayout
android:id="#+id/viewError"
android:layout_width="100dp"
android:layout_height="100dp"
android:background="#color/colorPrimary"
app:showError="#{viewModel.showError}" />
</LinearLayout>
</layout>
3: Create showError and showLoading variables in Viewmodel.
And assign the viewModel variable to the binding.
class MainViewModel: ViewModel() {
val showError: MutableLiveData<Boolean> = MutableLiveData()
val showLoading: MutableLiveData<Boolean> = MutableLiveData()
init {
showError.postValue(false)
showLoading.postValue(true)
}
}
class MainActivity : AppCompatActivity() {
private val viewModel = MainViewModel()
private lateinit var binding: ActivityMainBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
binding.lifecycleOwner = this
binding.viewModel = viewModel
initViews()
}
private fun initViews() {
binding.btnAdd.setOnClickListener {
viewModel.showError.postValue(true)
viewModel.showLoading.postValue(false)
}
}
}

How can a ViewModel function access the Place instance returned by PlaceSelectionListener of AutocompleteSupportFragment?

I am building an Android app using Kotlin.
I have a layout that contains a create_button. When the user clicks the button, the onClick should call onCreateJourney() in my ViewModel. This function requires the selectedPlaceId parameter to update a Journey entity with its value.
In my Fragment, I use the AutocompleteSupportFragment for the user to search and choose the desired place. This works well, as onPlaceSelected() returns the correct place in response to the user's selection. But I can't figure out how to use the returned place id value (p0.id) in my ViewModel onCreateJourney().
At this stage, the compiler throws this error:
cannot find method onCreateJourney() in class com.example.traveljournal.journey.NewJourneyViewModel
Please, can you shed some light on this issue for me?
My UI (.xml fragment layout):
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context=".journey.NewJourneyFragment">
<data>
<variable
name="newJourneyViewModel"
type="com.example.traveljournal.journey.NewJourneyViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/whereQuestion"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="10dp"
android:text="#string/whereQuestion"
android:textSize="18sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.027"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/journeyBckgImageView" />
<androidx.cardview.widget.CardView
android:id="#+id/cardView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent">
</androidx.cardview.widget.CardView>
<fragment
android:id="#+id/autocomplete_fragment"
android:name="com.google.android.libraries.places.widget.AutocompleteSupportFragment"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="10dp"
android:layout_marginTop="10dp"
android:layout_marginEnd="10dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/whereQuestion" />
<Button
android:id="#+id/create_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:onClick="#{() -> newJourneyViewModel.onCreateJourney()}"
android:text="#string/createJourneyButton"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
My ViewModel
class NewJourneyViewModel (
private val journeyKey: Long = 0L,
val database: TravelDatabaseDao) : ViewModel() {
private var viewModelJob = Job()
private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)
private val _navigateToJourneys = MutableLiveData<Boolean?>()
val navigateToJourneys: LiveData<Boolean?>
get() = _navigateToJourneys
fun doneNavigating() {
_navigateToJourneys.value = null
}
fun onCreateJourney(selectedPlaceId: String) {
uiScope.launch {
withContext(Dispatchers.IO) {
val journey = database.getJourney(journeyKey) ?: return#withContext
journey.placeId = selectedPlaceId
database.updateJourney(journey)
}
_navigateToJourneys.value = true
}
}
override fun onCleared() {
super.onCleared()
viewModelJob.cancel()
}
}
My Fragment
class NewJourneyFragment : Fragment(), PlaceSelectionListener {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
(activity as AppCompatActivity).supportActionBar?.title = getString(R.string.createJourney)
val binding: FragmentNewJourneyBinding = DataBindingUtil.inflate(
inflater,
R.layout.fragment_new_journey, container, false
)
val application = requireNotNull(this.activity).application
val arguments = NewJourneyFragmentArgs.fromBundle(arguments!!)
val dataSource = TravelDatabase.getInstance(application).travelDatabaseDao
val viewModelFactory = NewJourneyViewModelFactory(arguments.journeyKey, dataSource)
val newJourneyViewModel =
ViewModelProviders.of(
this, viewModelFactory).get(NewJourneyViewModel::class.java)
binding.newJourneyViewModel = newJourneyViewModel
newJourneyViewModel.navigateToJourneys.observe(this, Observer {
if(it == true) {
this.findNavController().navigate(
NewJourneyFragmentDirections.actionNewJourneyDestinationToJourneysDestination())
newJourneyViewModel.doneNavigating()
}
})
if (!Places.isInitialized()) {
this.context?.let { Places.initialize(it, getString(R.string.apiKey), Locale.US) }
}
val autocompleteFragment = childFragmentManager.findFragmentById(R.id.autocomplete_fragment)
as? AutocompleteSupportFragment
autocompleteFragment?.setOnPlaceSelectedListener(this)
autocompleteFragment!!.setHint(getString(R.string.destinationExample))
autocompleteFragment!!.setPlaceFields(Arrays.asList(Place.Field.ID, Place.Field.NAME))
return binding.root
}
#ExperimentalStdlibApi
override fun onPlaceSelected(p0: Place) {
Log.i("PLACE", "Place: " + p0.name + ", " + p0.id)
}
override fun onError(status: Status) {
Toast.makeText(this.context,""+status.toString(),Toast.LENGTH_LONG).show()
Log.i("ERROR", "An error occurred: " + status)
}
}

You have to pass the field selectedPlaceId as an argument in the xml :
android:onClick="#{() -> newJourneyViewModel.onCreateJourney(newJourneyViewModel.selectedPlaceId)}"
How will you get the selectedPlaceId in view model depends on your programming logic.
For testing purposes, you can hardcode the value.

In NewJourneyViewModel, I set up selectedPlaceId as MutableLiveData.
val selectedPlaceId = MutableLiveData<String>()
In NewJourneyFragment, I used lateinit to create a field for NewJourneyViewModel called newJourneyViewModel and initialized it in onCreateView().
private lateinit var newJourneyViewModel : NewJourneyViewModel
Now having access to my ViewModel outside of onCreateView(), in my Fragment onPlaceSelected() method I can set the value of selectedPlaceId to p0.id.
newJourneyViewModel.selectedPlaceId.value = p0.id
If anybody can come up with a better and safer approach on this, it will be highly appreciated.