I have the weirdest bug on Kotlin, and after two days of trying I finally asking for help.
The problem is simple : I have two fragment and one activity, the first fragment A is a form, with a validate button, when I click on validate, the fragment B replace the fragment A, and if I press back, the fragment A show up again with the form filled.
My problem is that after the fragment is shown again, I can click on the button but the listener is not call, so I can't go to the fragment B again. The strange thing is that the other listener are properly working, so I'm thinking it's because the previous fragment is catching the onClick, but idk what to do. Here is some code :
ViewUtils :
fun addFragment(activity: Activity, fragment: androidx.fragment.app.Fragment, container: Int) {
val fragmentManager = (activity as AppCompatActivity).supportFragmentManager
val pendingTransaction = fragmentManager.beginTransaction().add(container, fragment, fragment.javaClass.name)
pendingTransaction.commitAllowingStateLoss()
}
fun replaceFragment(manager: FragmentManager, fragment: androidx.fragment.app.Fragment, container: Int) {
if (fragment.isAdded) return
val pendingTransaction = mangaer.beginTransaction()
pendingTransaction.replace(container, fragment, fragment.javaClass.name)
pendingTransaction.commitAllowingStateLoss()
}
fun removeFragment(activity: Activity, fragment: Fragment) {
val manager = (activity as AppCompatActivity).supportFragmentManager
val trans = manager.beginTransaction()
trans.remove(fragment)
trans.commit()
manager.popBackStack()
}
Activity :
fun displayFragmentA() {
ViewUtils.replaceFragment(supportFragmentManager, FragmentA,
R.id.fragmentLayout)
}
fun FragmentB() {
ViewUtils.replaceFragment(supportFragmentManager, FragmentB,
R.id.fragmentLayout)
}
Fragment A
class AFragment : BaseFragment(), AContract.View {
companion object {
#JvmStatic
fun newInstance(): AFragment {
val fragment = AFragment()
return fragment
}
}
#Inject
lateinit var APresenter: AContract.Presenter<AContract.View>
//end region
//region lifecycle
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment_A_layout, container, false)
}
override fun onResume() {
super.onResume()
button_validate.setOnClickListener {
presenter.goToNextStep()
}
}
override fun onAttach(context: Context) {
AndroidSupportInjection.inject(this)
super.onAttach(context)
}
The listener was set in the onViewCreated but I tried moving it to onResume (didn't change anything)
Fragment B code is not important I think, but I can add it if it helps.
Any help is welcome, I really don't know what's going on, the replace/add methods were there before I came to the project, they are not perfect but they are working elsewhere on the project.
I try using breakpoint, the button is not null but we never enter the listener.
Edit : I tried on 3 differents devices, I don't have the bug with a Sony Android 9, but with Huawei et One plus 6 Android 10, the problem persist ..
Ok so after asking to a lot of people, the only solution I found is not using kotlin.synthetic, and using findById instead :
view.findViewById<Button>(R.id.button_validate.setOnClickListener
Related
I create ViewModel class at fragment, but viewModel is not saving after rotation - every time i got new Viewmodel instance. Where is problem?
Acrivity:
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
supportFragmentManager.beginTransaction()
.addToBackStack(null)
.replace(R.id.main_container, VideoFragment())
.commit()
}
}
Fragment:
class VideoFragment: Fragment() {
lateinit var viewModel: VideoViewModel
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
viewModel = ViewModelProvider(this).get(VideoViewModel::class.java)
return inflater.inflate(R.layout.fragment_video, container, false)
}
}
ViewModel:
class VideoViewModel: ViewModel() {
init {
Log.i("XXX", "$this ")
}
}
if i will use "requireActivity()" - as ViewModelStoreOwner - viewModel isnt recreate, but its will bound to activity lifecycle.
viewModel = ViewModelProvider(requireActivity()).get(VideoViewModel::class.java)
This is because you are replacing your Fragment on every configuration change when the Activity is recreated. The FragmentManager already retains your Fragment for you. You should commit the transaction only on the initial creation:
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
if (savedInstanceState == null) {
supportFragmentManager.beginTransaction()
.addToBackStack(null)
.replace(R.id.main_container, VideoFragment())
.commit()
}
}
}
Your problem is most likely caused due to the activity being destroyed and then created again after app is rotated.
To fix this you can give your fragment an id/tag when navigating and then when activity is rotated call your supportFragmentManager if there already exists an instance of your old fragment, if it does, navigate to old fragment instance, otherwise create a new instance just like you are doing now.
Wax911 (commented on 9 may 2020) answer to this question:
https://github.com/InsertKoinIO/koin/issues/693
He explains the problem with activities and their lifecycle when rotating the screen
I'm creating a shopping app where the user can choose next product from the fragment. That will open the next fragment of the same class with more products and so on. I want to use swipe to dismiss behaviour, so when I swipe my finger down I dissmiss the current fragment. It's essential that while swiping the current fragment the user will be able to see the fragment underneath, so I can only use add instead of replace. Here's the problem: When I use add in my fragment manager, the created fragments UI's overlap, which makes the user swipe multiple fragments at once and not show swiping animation. The fragment uses one xml layout so it shares id across all fragments so I have no way of controlling which layouts are disabled. How do I make the user only swipe one fragment/disable touching fragments underneath? The swipe to dissmis is working well with replace but that's not the point. Here's my code.
Activity:
class PullDismissActivity : AppCompatActivity(), PullDismissLayout.Listener {
private lateinit var viewModel: StackingFragmentsViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_pulldismiss)
viewModel = ViewModelProvider(this).get(StackingFragmentsViewModel::class.java)
supportFragmentManager.beginTransaction()
.add(R.id.pull, SwipeFragment(), null)
.addToBackStack(null) // name can be null
.commit()
val layout = findViewById<PullDismissLayout>(R.id.pull)
layout.setListener(this)
}
override fun onDismissed() {
viewModel.popBackStack()
supportFragmentManager.popBackStack()
}
override fun onShouldInterceptTouchEvent(): Boolean {
return false
}
Fragment:
class SwipeFragment : Fragment() {
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val viewModel = ViewModelProvider(requireActivity()).get(StackingFragmentsViewModel::class.java)
viewModel.addFragment(this.hashCode())
val fragid = view.findViewById<TextView>(R.id.fragid)
fragid?.text = System.currentTimeMillis().toString()
val button = view.findViewById<Button>(R.id.button)
button.setOnClickListener {
requireActivity().supportFragmentManager.beginTransaction()
.add(R.id.pull, SwipeFragment(), null)
.addToBackStack(null)
.commit()
}
}
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? {
return inflater.inflate(R.layout.fragment,container,false)
}
Example of what i'm trying to achieve https://i.stack.imgur.com/lhp10.png
I'm stuck on the part where i need to switch to createUserFragment from defaultFragment
i attached this to my button, but nothing happens when i press it, not sure what's wrong there
MainActivity
class MainActivity : AppCompatActivity() {
lateinit var appBarConfiguration: AppBarConfiguration
lateinit var navController: NavController
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
navController = findNavController(R.id.hostFragment)
appBarConfiguration = AppBarConfiguration(navController.graph,drawer_layout)
NavigationUI.setupActionBarWithNavController(this, navController,drawer_layout)
NavigationUI.setupWithNavController(navigation_drawer,navController)
}
}
override fun onSupportNavigateUp(): Boolean {
return NavigationUI.navigateUp(navController,appBarConfiguration)
}
defaultFragment
class defaultFragment : Fragment() {
private lateinit var binding: defaultFragmentBinding
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
binding = defaultFragmentBinding.inflate(inflater)
return (binding.root)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
binding.createNewBlankFAB.setOnClickListener{
val transaction = (activity as MainActivity).supportFragmentManager.beginTransaction()
transaction.replace(R.id.defaultFragment, createUserFragment())
transaction.disallowAddToBackStack()
transaction.commit()
}
}
}
My questions are:
1)How can i fix my thing?
2)Will it work properly? I.e no memory leaks or some other funky stuff
3)Do i have to use another fragment for data input or maybe there's another way?
UPDATE
I stil have no idea how this works, but apparently i was replacing wrong fragment, i switched this R.id.defaultFragment in transaction.replace to R.id.hostFragment from which, i assume, all other fragments spawn, but now it just spawn on top of my existing fragment and the drawer button doesn't change its state, i guess i have to either do all of this differently or somehow pass to the drawer navigation information that current fragment was changed?
This is how we navigate within fragments in Navigation component library . We use navigate to then id of the destination Fragment which is defined in navgraph
binding.createNewBlankFAB.setOnClickListener{
Navigation.findNavController(view).navigate(R.id.createUserFragment);
}
I think you have to call "transaction.add" instead of "replace" since you are calling your fragment from an activity. Replace is called when you call a fragment from another fragment, I believe.
i am currently programming an app in Android Studio and i am having a big issue. The main problem is, that i want an activity with a fragment in it and this fragment has got a spinner. I wanted to find the spinner by id, but it always returned null and i read that i can't use findViewById if it is not in the ContentView i just set. So i am currently trying to find the fragment that contains the spinner, but i also can't find the fragment, i tried findFragmentById and findViewById from the FragmentManager. I always get a TypeCastException and if i try findFragmentById(...)!! it throws a NullPointer.
This is my MainActivity:
class MainActivity : AppCompatActivity() {
private val manager: FragmentManager? = supportFragmentManager
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
showDeviceFragment()
val fragment = manager!!.findFragmentById(R.id.fragment_holder) as DeviceFragment
val options = arrayOf("Wandhalterung (Arm)", "Gestellhalterung (Arm)", "Gestellhalterung")
fragment.option.adapter = ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, options)
}
fun showDeviceFragment() {
val transaction = manager!!.beginTransaction()
val fragment = DeviceFragment()
transaction.add(R.id.fragment_holder, fragment, "DEVICE_FRAGMENT")
transaction.addToBackStack(null)
transaction.commit()
}
}
And this is the DeviceFragment:
class DeviceFragment : Fragment() {
lateinit var option : Spinner
companion object {
fun newInstance(): DeviceFragment {
return DeviceFragment()
}
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.fragment_device, container, false)
option = view.spinner
return inflater?.inflate(R.layout.fragment_device, container, false)
}
}
The fragment_holder just is a FrameLayout.
Thanks in advance
Few things:
1) No need to hold reference for supportFragmentManager, use it directly (because i am not sure if it will be null when Activity is initialized)
2) Try removing addToBackStack(null) and using findFragmentByTag("DEVICE_FRAGMENT")
3) Most importantly, Don't try to access "things" of Fragment from Activity, do those Adapter initialization/fill in the Fragment itself. Because Fragment has its own lifecycle and you may try to access "things" at wrong lifecycle
I have the single activity with several fragments on top, as Google recommends. In one fragment I wish to place a switch, and I wish to still know it's state when I come back from other fragments. Example: I am in fragment one, then I turn on the switch, navigate to fragment two or three, go back to fragment one and I wish to load that fragment with that switch in the on position as I left it.
I have tried to copy the examples provided by google advocates, just to see the code to fail hard and do nothing.
/////////////////////////////////////////////////////////////////
//Inside the first fragment:
class myFragment : Fragment() {
companion object {
fun newInstance() = myFragment()
}
private lateinit var viewModel: myViewModel
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.my_fragment, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
**viewModel = ViewModelProvider(this, SavedStateVMFactory(this)).get(myViewModel::class.java)
//Here I was hoping to read the state when I come back.
switch_on_off.isChecked = viewModel.getSwRoundTimerInit()**
subscribeToLiveData() //To read liveData
switch_on_off.setOnCheckedChangeListener { _, isChecked ->
viewModel.setOnOff(isChecked)
}
}//End of onActivityCreated
//other code...
/////////////////////////////////////////////////////////////////////////
//On the fragment ViewModel
class myViewModel(private val **mState: SavedStateHandle**) : ViewModel() {
//SavedStateHandle Keys to save and restore states in the App
private val swStateKey = "SW_STATE_KEY"
private var otherSwitch:Boolean //other internal states.
//Init for the other internal states
init {
otherSwitch = false
}
fun getSwRoundTimerInit():Boolean{
val state = mState[swStateKey] ?: "false"
return state.toBoolean()
}
fun setOnOff(swValue:Boolean){
mState.set(swStateKey, swValue.toString())
}
}
This does not work. It always loads the default (off) value, as if the savedState is null all the time.
change
//fragment scope
viewModel = ViewModelProvider(thisSavedStateVMFactory(this)).get(myViewModel::class.java)
to
//activity scope
viewModel = activity?.let { ViewModelProviders.of(it,SavedStateVMFactory(this)).get(myViewModel::class.java) }
https://developer.android.com/topic/libraries/architecture/viewmodel#sharing