I want the value to increase when I press the button and write it in the textview.
However, the code below shows the increasing value as Log
But, on screen, the value in textview does not change.
I'm not sure what's wrong. Please let me know if you know.
Fragment.kt
class SettingFragment : Fragment(), View.OnClickListener {
companion object {
fun newInstance() = SettingFragment()
private val TAG = "SettingFragment"
}
private lateinit var viewModel: SettingViewModel
private lateinit var binding: FragmentSettingBinding
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_setting, container, false)
return binding.root
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewModel = ViewModelProvider(this).get(SettingViewModel::class.java)
binding.lifecycleOwner = this
binding.button.setOnClickListener(this)
}
override fun onClick(v: View?) {
viewModel.increase()
Log.d(TAG, "Log Data" + viewModel.testInt.value)
}
}
FragmentViewModel
class SettingViewModel : ViewModel() {
val testInt: MutableLiveData<Int> = MutableLiveData()
init {
testInt.value = 0
}
fun increase() {
testInt.value = testInt.value?.plus(1)
}
}
fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<layout>
<data>
<variable
name="viewModel"
type="com.example.ui.setting.SettingViewModel" />
</data>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".ui.setting.SettingFragment">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#{String.valueOf(viewModel.testInt)}" />
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
/>
</LinearLayout>
</layout>
<variable
name="viewModel"
type="com.example.ui.setting.SettingViewModel" />
This viewModel variable doesn't bind to a certain variable programmatically. So, when the value incremented, it won't reflect to the layout.
To fix this set the fragment's viewModel to this value:
viewModel = ViewModelProvider(this).get(SettingViewModel::class.java)
binding.viewModel = viewModel // <<<<< Here is the change
binding.lifecycleOwner = this
binding.button.setOnClickListener(this)
Side note:
You shouldn't use onActivityCreated() as it's is deprecated as of API level 28; you can normally its part of code to onCreateView(). And you can check here for other alternatives.
Related
I'm a beginner android developer and I got stuck with an issue.
viewModel keeps the states change data related to a fragment and when the user navigate to some fragment then the viewModel no longer keeps the states.
What I want is that when the user change something in the fragment and after that navigate to other fragment and then come back to the fragment where he changes something, he should see the changes he made.
Solutions are there for storing ex. shared_preference & Room, but my requirement is that I only want to keep the state data alive until the use closed the App.
I've googling so far but still didn't understand the approach developers follow to do these things. So can you also provide some guidance on approaches I should follow that consider the best practices. My main motive is to learn.
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
<variable
name="homeViewModel"
type="com.android.example.presentation.home.HomeViewModel" />
</data>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".presentation.home.HomeFragment">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:keepScreenOn="true">
<TextView
android:id="#+id/sampleText"
android:text="#{String.valueOf(homeViewModel.sampleText)}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.5" />
<Button
android:id="#+id/sampleButton"
android:onClick="#{() -> homeViewModel.samplePressed()}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="32dp"
android:text="Button"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/sampleText" />
</androidx.constraintlayout.widget.ConstraintLayout>
</FrameLayout>
</layout>
class HomeViewModel : ViewModel() {
private val _sampleText = MutableLiveData(0)
val sampleText : LiveData<Int>
get() = _sampleText
fun samplePressed() {
_sampleText.postValue(1)
}
}
Thanks to the comment from Vivek Gupta
This can be achieved by scoping the ViewModel to the activity's lifecycle
previous
class HomeFragment : Fragment() {
private val viewModel: HomeViewModel by viewModels()
}
Now change it this
class HomeFragment : Fragment() {
private val viewModel: HomeViewModel by activityViewModels()
}
Edit: another way to do this if we have viewModelFactory
class HomeFragment : Fragment() {
private lateinit var binding: FragmentHomeBinding
private lateinit var mainRepository: MainRepository
private lateinit var viewModel: HomeViewModel
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?) : View {
binding = DataBindingUtil.inflate(inflater, R.layout.fragment_home, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
mainRepository = MainRepository(RetrofitInstance.api)
val viewModelFactory = HomeViewModelFactory(mainRepository)
viewModel = ViewModelProvider(requireActivity(), viewModelFactory).get(HomeViewModel::class.java)
binding.homeViewModel = viewModel
binding.lifecycleOwner = viewLifecycleOwner
}
}
I have a problem using viewmodel in fragment with data binding.
In my programm i'm using only one activity and fragments. I organized transitions between fragments using navigation. And i want to use data binding in my fragment, but when running the application only with binding, everything works well when I pass to the binding viewmodel when switching to this fragment of the application, it crashes.
I would be very grateful for your help!
My fragment
class TimeSettings : Fragment() {
private lateinit var viewModel: TimeSettingsViewModel
private lateinit var binding: FragmentTimeSettingsBinding
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = FragmentTimeSettingsBinding.inflate(inflater, container, false)
binding.lifecycleOwner = this
binding.viewmodel = viewModel;
return binding.root
}
}
Object for viewmodel
object TimeData {
var inhale: Int = 4
private val _currentTimeInhale = MutableLiveData<Int>()
val currentTimeInhale: LiveData<Int>
get() = _currentTimeInhale
init{
_currentTimeInhale.value = inhale
}
fun changeCurrentTimeInhale(){
_currentTimeInhale.value = 5
}
}
Viewmodel
class TimeSettingsViewModel : ViewModel() {
val currentInhale: LiveData<Int>
get() = TimeData.currentTimeInhale
fun onChange() = TimeData.changeCurrentTimeInhale()
}
xml file for fragment
<?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="viewmodel"
type="ivakin.first.my_first_app.viewmodels.TimeSettingsViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/textView"
android:layout_width="95dp"
android:layout_height="59dp"
android:text="#{viewmodel.currentInhale}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.452" />
<Button
android:id="#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Set"
android:onClick="#{()->viewmodel.onChange()"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/textView" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
U Forgot Initialize ViewModel :
viewmodel = TimeSettingsViewModel()
Also dont use return binding.root
I've switched from using LiveData to StateFlow in my app and also applied it in Data Binding. But after changing the value of StateFlow, the UI is not updating. From what I understand from the StateFlow docs, I only have to assign a new value to the value property of a StateFlow to update its consumers.
Below, I have a time field which I update the value by using an MaterialTimePicker dialog. But after I change the time and assign a new value to the selectedAlarm property (StateFlow) of my viewmodel, the UI is not updating for the new value. I'm not sure where is my mistake or what is lacking.
Below is my AlarmFormFragment:
#AndroidEntryPoint
class AlarmFormFragment : Fragment() {
private val alarmsViewModel: AlarmsViewModel by activityViewModels()
private var _binding: FragmentAlarmFormBinding? = null
private val binding get() = _binding!!
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentAlarmFormBinding.inflate(inflater, container, false)
binding.alarmsViewModel = alarmsViewModel
binding.lifecycleOwner = viewLifecycleOwner
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
setUpTimeField()
}
private fun setUpTimeField() {
alarmsViewModel.selectedAlarm.value.let { alarm ->
binding.llTimeField.setOnClickListener {
// Create and then show time picker
val picker =
MaterialTimePicker.Builder()
.setTimeFormat(TimeFormat.CLOCK_12H)
.setTitleText("Set Time")
.setHour(alarm.time.get(Calendar.HOUR_OF_DAY))
.setMinute(alarm.time.get(Calendar.MINUTE))
.build()
picker.addOnPositiveButtonClickListener {
alarm.time.set(Calendar.HOUR_OF_DAY, picker.hour)
alarm.time.set(Calendar.MINUTE, picker.minute)
alarmsViewModel.selectedAlarm.value = alarm
}
picker.show(childFragmentManager, "TIME_INPUT_DIALOG")
}
}
}
}
Below is the xml file for AlarmFormFragment:
<?xml version="1.0" encoding="utf-8"?>
<layout>
<data>
<import type="com.example.myclock.utilities.Utility" />
<import type="com.example.myclock.utilities.SnoozeUtils"/>
<variable
name="alarmsViewModel"
type="com.example.myclock.viewmodels.AlarmsViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
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=".fragments.AlarmFormFragment">
<!-- Form Fields -->
<LinearLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent">
<!-- Time Field -->
<LinearLayout
android:id="#+id/llTimeField"
style="#style/FormFieldLayoutStyle">
<TextView
style="#style/FormFieldTextStyle.Label"
android:text="#string/label_time" />
<TextView
android:id="#+id/tvTime"
style="#style/FormFieldTextStyle.Value"
android:text="#{Utility.INSTANCE.timeToString(alarmsViewModel.selectedAlarm.value.time)}" />
</LinearLayout>
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
And below is my AlarmsViewModel:
#HiltViewModel
class AlarmsViewModel #Inject constructor(
private val alarmsRepository: AlarmsRepository
) : ViewModel() {
private val _alarms = MutableStateFlow<List<Alarm>>(emptyList())
val alarms: StateFlow<List<Alarm>> get() = _alarms
var selectedAlarm = MutableStateFlow(Alarm())
...
}
Below is class for the data Alarm:
#Parcelize
#Entity
class Alarm(
#PrimaryKey(autoGenerate = true) val id: Int = 0,
var time: Calendar = Calendar.getInstance(),
...
) : Parcelable {
...
}
Do fragment need a very precise way of handling the texts that are set in the xml of the fragment ?
I had two times very similar problems : text written in xml cannot be updated properly.
Here is my first fragment. I previously had a foolish text written in the xml for the textview 'msg2ndfragment'. The issue I had was that during the onViewCreated, the text sent by the new Activity to the text would overlap the foolish text written in the Xml.
So I removed the foolish text, and now it is fine. (I could update thee text three times in a row it would work as long as the text was not initially defined in the xml),
class SecondFragment : Fragment() {
//Passer par new instance pour créé le fragment en lui donnant le nom à afficher
companion object {
fun newInstance(title: String?): SecondFragment {
val fragmentSecond = SecondFragment()
val args = Bundle()
args.putString(MainActivity.MESSAGE_SECOND_ACTIVITE, title)
fragmentSecond.arguments = args
return fragmentSecond
}
}
private lateinit var viewModel: SecondViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
return inflater.inflate(R.layout.second_fragment, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewModel = ViewModelProviders.of(this).get(SecondViewModel::class.java)
val message = arguments!!.getString(MainActivity.MESSAGE_SECOND_ACTIVITE, "")
val aries = view?.findViewById<TextView>(R.id.msg2ndfragment);
aries?.text = message
}
}
But now, I have a very similar issue: in a different fragment in another activity I have an editText with a hint. I want to make the hint disappear. Same issue : if the hint is written in the Xml : any text written by the user will only overlap the old text. If I initially define the hint dynamically, the hint disappears when the user starts writing.
class MainFragment : Fragment() {
companion object {
fun newInstance() = MainFragment()
}
private lateinit var viewModel: MainViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View {
return inflater.inflate(R.layout.main_fragment, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
viewModel = ViewModelProviders.of(this).get(MainViewModel::class.java)
val aries = view?.findViewById<Button>(R.id.btnGo2ndActivity);
aries?.setOnClickListener { onGoSecondFragmentClick(it) }
Log.d("p1", "p1");
//Faire disparaitre le int au touch car cela ne se fait pas automatiquement
val edTxtTo2nd = view?.findViewById<EditText>(R.id.edt2ndActEditText)
edTxtTo2nd?.hint = "a"
Log.d("pouf", "pouf");
/*val edTxtTo2nd = view?.findViewById<EditText>(R.id.edt2ndActEditText)
edTxtTo2nd?.setOnClickListener(View.OnClickListener { v ->
edTxtTo2nd?.setHint("")
}) */
}
private var listener: onMvmtClickListener? = null
public interface onMvmtClickListener {
fun onNextActivityClick(name1: String)
}
// Store the listener (activity) that will have events fired once the fragment is attached
override fun onAttach(context: Context) {
super.onAttach(context)
if (context is onMvmtClickListener) {
listener = context as onMvmtClickListener
} else {
throw ClassCastException(
"$context must implement nMvmtClickListener"
)
}
}
fun onGoSecondFragmentClick(v: View?) {
val nom = view?.findViewById<EditText>(R.id.edt2ndActEditText);
listener?.onNextActivityClick(nom?.text.toString())
}
}
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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:id="#+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.main.MainFragment">
<TextView
android:id="#+id/message"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<Button
android:id="#+id/btnGo2ndActivity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="21dp"
android:text="#string/go_to_2nd_act"
app:layout_constraintTop_toBottomOf="#+id/edt2ndActEditText"
tools:layout_editor_absoluteX="111dp"
tools:ignore="MissingConstraints" />
<EditText
android:id="#+id/edt2ndActEditText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="35dp"
android:layout_marginBottom="21dp"
android:ems="10"
android:inputType="textPersonName"
app:layout_constraintBottom_toTopOf="#+id/btnGo2ndActivity"
app:layout_constraintTop_toTopOf="#+id/message"
tools:layout_editor_absoluteX="95dp"
tools:ignore="MissingConstraints" />
</androidx.constraintlayout.widget.ConstraintLayout>
Edit : here are the main_activity kotelin and xml
class MainActivity : AppCompatActivity(), MainFragment.onMvmtClickListener {
companion object{
const val MESSAGE_SECOND_ACTIVITE = "Message.s
econd.activite"
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.main_activity)
if (savedInstanceState == null) {
supportFragmentManager.beginTransaction()
.replace(R.id.container, MainFragment.newInstance())
.commitNow()
}
}
override fun onNextActivityClick(name1: String) {
var intent = Intent(this, SecondActivity::class.java)
intent.putExtra(MESSAGE_SECOND_ACTIVITE, name1)
startActivity(intent)
}
}
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id
/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<fragment
android:id="#+id/fragment"
android:name="com.example.myapplication.ui.main.MainFragment"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</FrameLayout>
Using this workaround to define any text or hint feels wrong to me. How can I define them in the Xml of the fragment without having this overlap issue ?
Thank you in advance for any help.
I went through couple of examples but either they have too many abstractions or out of date tutorials. I would like to implement this feature in the minimum possible way. I need help with the UserForm class here with User passed as arguments in a Navigational Architecture.
Module app build.gradle I've added this
android {
...
dataBinding {
enabled = true
}
}
User class
#Parcelize
data class User(var first: String, var last: String): Parcelable
FormFragment.kt
class UserForm: Fragment() {
private val user by lazy {
arguments?.getParcelable("user") ?: User("John", "Doe")
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_form, container, false)
}
}
fragment_form.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="user" type="data.User" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<EditText
android:id="#+id/first"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="text"
android:text="#{user.first}" />
<EditText
android:id="#+id/last"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="text"
android:text="#{user.last}" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
Some snippets
modify your code below:
FormFragment.kt
class UserForm: Fragment() {
private val user by lazy {
arguments?.getParcelable("user") ?: User("John", "Doe")
}
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val binding = FragmentFormBinding.inflate(inflater, container, false).apply {
user = this#UserForm.user
}
return binding.root
}
}
Explanation:
Because you used DataBinding in fragment_form.xml, the corresponding FragmentFormBinding class will be automatically generated
We usually use XxxBinding.inflate instead of inflater.inflate (layoutid, container, false)
After FragmentFormBinding.inflate, we bind the user object to fragment_form.xml