Develop Reference

safeargs argument not found in NavDirections

I have implemented an argument to be passed between fragments in nav_graph, however when I attempt to set the argument in the originating fragment, the argument is not found by the NavDirections.
Note that Navigation works fine before trying to pass the argument.
If I do a Clean Project I lose the NavDirections. If I do a Rebuild I lose the argument.
Gradle:app
//Navigation
implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"
implementation "androidx.navigation:navigation-ui-ktx:$nav_version"
apply plugin: "androidx.navigation.safeargs.kotlin"
nav_graph.xml
<fragment
android:id="#+id/destination_home"
android:name="com.android.joncb.flightlogbook.HomeFragment"
android:label="#string/lblHome"
tools:layout="#layout/fragment_home">
<action
android:id="#+id/action_home_to_fltHistory"
app:destination="#id/destination_fltHistory" />
<action
android:id="#+id/action_home_to_stats"
app:destination="#id/destination_statistics" />
<action
android:id="#+id/action_home_to_newFlight"
app:destination="#id/destination_newFlight" />
<action
android:id="#+id/action_home_to_fltDetails"
app:destination="#id/destination_fltDetails" />
<argument
android:name="fltData"
app:argType="string" />
</fragment>
and in my Home Fragment I get the error "Unresolved reference: fltData"
card_nextFlight.setOnClickListener {
val actionDetails = HomeFragmentDirections.actionHomeToFltDetails()
actionDetails.fltData ( flightData.toString())
Navigation.findNavController(it).navigate(actionDetails)
}
flightData is a data class
data class FlightDTO(
var airlineName: String, var faCode: String, var fltNo: String, var aircraft: String,
var depAP: String, var arrAP: String, var schedDep: String, var schedArr: String,
var date: String, var leg: Int = 0, var actDep: String = "", var actArr: String = "" ){
...
override fun toString(): String {
return "$airlineName $faCode $fltNo $aircraft $depAP $schedDep $arrAP $schedDep $date"
}
}
I want to pass the class ideally by making the class Parcelable, but until I can pass a string, there is no point venturing down the parcel line.

You are writing your XML wrong, think like this : The way I structure my XML properties is the way the generated code will look like and received between destinations sort of...
So basically in your nav_graph.xml you should change to:
<fragment
android:id="#+id/destination_home"
android:name="com.android.joncb.flightlogbook.HomeFragment"
android:label="#string/lblHome"
tools:layout="#layout/fragment_home">
<action
android:id="#+id/action_home_to_fltHistory"
app:destination="#id/destination_fltHistory" />
<action
android:id="#+id/action_home_to_stats"
app:destination="#id/destination_statistics" />
<action
android:id="#+id/action_home_to_newFlight"
app:destination="#id/destination_newFlight" />
<action
android:id="#+id/action_home_to_fltDetails"
app:destination="#id/destination_fltDetails">
<argument
android:name="fltData"
app:argType="string" />
</action>
</fragment>
and in your destination it should look something like:
<fragment
android:id="#+id/destination_fltDetails"
android:name="com.android.joncb.flightlogbook.FlightDetailsFragment"
android:label="#string/lblFlightDetails"
tools:layout="#layout/fragment_flight_details">
<argument
android:name="fltData"
app:argType="string" />
</fragment>
and in your flight details fragment the properties are received by using:
private val args: FlightDetailsFragmentArgs by navArgs()
println(args.fltData) // prints the navigation data
UPDATE:
Forgot to mention your OnClickListener in your Home fragment that would look more like this:
card_nextFlight.setOnClickListener {
val actionDetails = HomeFragmentDirections.actionHomeToFltDetails(flightData.toString())
Navigation.findNavController(it).navigate(actionDetails)
}

For my case, I wrote a buggy code like that -
NavController navController = NavHostFragment.findNavController(this);
NavDirections navDirections = MyDestinationFragmentDirections.actionMyAction(myArgumentValue);
navController.navigate(navDirections.getActionId());
Then I change the last line into this -
navController.navigate(navDirections);
And finally,it worked as expected!!!
The logic behind this was, in NavController class the method which accepting int (resId of action) always put null argument -
public void navigate(#IdRes int resId) {
navigate(resId, null);
}
So we should use -
public void navigate(#NonNull NavDirections directions) {
navigate(directions.getActionId(), directions.getArguments());
}
method if we are willing to pass an arguments via an action.

my mistake was the following. I had something like
NavDirections action =
SpecifyAmountFragmentDirections
.actionSpecifyAmountFragmentToConfirmationFragment();
I changed to something like
ConfirmationAction action =
SpecifyAmountFragmentDirections
.actionSpecifyAmountFragmentToConfirmationFragment();

Rather than pass a data class, I have created a JSON String and passed a string
card_nextFlight.setOnClickListener {
val dataString = flightData.toJSONString()
val actionDetails = HomeFragmentDirections.actionHomeToFltDetails(dataString)
Navigation.findNavController(it).navigate(actionDetails)
}
To get this to work I had to modify the actionHomeToFltDetails function to receive a string in HomeFragmentsDirections
fun actionHomeToFltDetails(fltData: String): NavDirections = ActionHomeToFltDetails(fltData)
}
I could not get #Lucho approach to handle the arg in the destination fragment to work so reverted to bundle management, and converted the JSON string back to a data class
const val ARG_PARAM1 = "fltData"
.
.
.
arguments?.let {
argFltData = it.getString(ARG_PARAM1)
Log.e("args","Passed Argument: $argFltData")
fltData = gson.fromJson(argFltData, FlightDTO::class.java)
}
Thanks again for your input and I hope this helps someone else through the drama.

Android Navigation Component back button not working

I'm using the Navigation Component in android where I have set 6 fragments initially. The problem is when I added a new fragment (ProfileFragment).
When I navigate to this new fragment from the start destination, pressing the native back button does not pop the current fragment off. Instead, it just stays to the fragment I'm in - the back button does nothing.
Here's my navigation.xml:
<?xml version="1.0" encoding="utf-8"?>
<navigation 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/dashboard_navigation"
app:startDestination="#id/dashboardFragment"
>
<fragment
android:id="#+id/dashboardFragment"
android:name="com.devssocial.localodge.ui.dashboard.ui.DashboardFragment"
android:label="DashboardFragment"
>
<action
android:id="#+id/action_dashboardFragment_to_newPostFragment"
app:destination="#id/newPostFragment"
app:enterAnim="#anim/slide_in_up"
app:exitAnim="#anim/slide_out_down"
app:popEnterAnim="#anim/slide_in_up"
app:popExitAnim="#anim/slide_out_down"
/>
<action
android:id="#+id/action_dashboardFragment_to_notificationsFragment"
app:destination="#id/notificationsFragment"
app:enterAnim="#anim/slide_in_up"
app:exitAnim="#anim/slide_out_down"
app:popEnterAnim="#anim/slide_in_up"
app:popExitAnim="#anim/slide_out_down"
/>
<action
android:id="#+id/action_dashboardFragment_to_mediaViewer"
app:destination="#id/mediaViewer"
app:enterAnim="#anim/slide_in_up"
app:exitAnim="#anim/slide_out_down"
app:popEnterAnim="#anim/slide_in_up"
app:popExitAnim="#anim/slide_out_down"
/>
<action
android:id="#+id/action_dashboardFragment_to_postDetailFragment"
app:destination="#id/postDetailFragment"
app:enterAnim="#anim/slide_in_up"
app:exitAnim="#anim/slide_out_down"
app:popEnterAnim="#anim/slide_in_up"
app:popExitAnim="#anim/slide_out_down"
/>
====================== HERE'S THE PROFILE ACTION ====================
<action
android:id="#+id/action_dashboardFragment_to_profileFragment"
app:destination="#id/profileFragment"
app:enterAnim="#anim/slide_in_up"
app:exitAnim="#anim/slide_out_down"
app:popEnterAnim="#anim/slide_in_up"
app:popExitAnim="#anim/slide_out_down"
/>
=====================================================================
</fragment>
<fragment
android:id="#+id/profileFragment"
android:name="com.devssocial.localodge.ui.profile.ui.ProfileFragment"
android:label="fragment_profile"
tools:layout="#layout/fragment_profile"
/>
</navigation>
In the image above, the highlighted arrow (in the left) is the navigation action I'm having troubles with.
In my Fragment code, I'm navigating as follows:
findNavController().navigate(R.id.action_dashboardFragment_to_profileFragment)
The other navigation actions are working as intended. But for some reason, this newly added fragment does not behave as intended.
There are no logs showing when I navigate to ProfileFragment and when I press the back button.
Am I missing something? or is there anything wrong with my action/fragment configurations?
EDIT:
I do not do anything in ProfileFragment. Here's the code for it:
class ProfileFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_profile, container, false)
}
}
And my activity xml containing the nav host:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
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">
<fragment
android:id="#+id/dashboard_navigation"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:navGraph="#navigation/dashboard_navigation"
app:defaultNavHost="true"/>
</FrameLayout>

if you are using setupActionBarWithNavController in Navigation Component such as:
setupActionBarWithNavController(findNavController(R.id.fragment))
then also override and config this methods in your main activity:
override fun onSupportNavigateUp(): Boolean {
val navController = findNavController(R.id.fragment)
return navController.navigateUp() || super.onSupportNavigateUp()
}
My MainActivity.kt
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
setupActionBarWithNavController(findNavController(R.id.fragment))
}
override fun onSupportNavigateUp(): Boolean {
val navController = findNavController(R.id.fragment)
return navController.navigateUp() || super.onSupportNavigateUp()
}
}

For anyone using LiveData in a previous Fragment which is a Home Fragment, whenever you go back to the previous Fragment by pressing back button the Fragment is starting to observe the data and because ViewModel survives this operation it immediately emits the last emitted value which in my case opens the Fragment from which I pressed the back button, that way it looks like the back button is not working the solution for this is using something that emits data only once. I used this :
class SingleLiveData<T> : MutableLiveData<T>() {
private val pending = AtomicBoolean()
/**
* Adds the given observer to the observers list within the lifespan of the given
* owner. The events are dispatched on the main thread. If LiveData already has data
* set, it will be delivered to the observer.
*
* #param owner The LifecycleOwner which controls the observer
* #param observer The observer that will receive the events
* #see MutableLiveData.observe
*/
#MainThread
override fun observe(owner: LifecycleOwner, observer: Observer<in T>) {
super.observe(owner, Observer { t ->
if (pending.compareAndSet(true, false)) {
observer.onChanged(t)
}
})
}
/**
* Sets the value. If there are active observers, the value will be dispatched to them.
*
* #param value The new value
* #see MutableLiveData.setValue
*/
#MainThread
override fun setValue(value: T?) {
pending.set(true)
super.setValue(value)
}

This problem happened to me while using MutableLiveData to navigate between fragments and was observing the live data object at more than one fragment.
I solved it by observing the live data object one time only or by using SingleLiveEvent instead of MutableLiveData. So If you're having the same scenario here, try to observe the live data object one time only or use SingleLiveEvent.

You can use this following for the Activity
onBackPressedDispatcher.addCallback(
this,
object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
onBackPressed()
// if you want onBackPressed() to be called as normal afterwards
}
}
)
For the fragment, It will be needed requireActivity() along with Callback
requireActivity().onBackPressedDispatcher.addCallback(
this,
object : OnBackPressedCallback(true) {
override fun handleOnBackPressed() {
requireActivity().onBackPressed()
// if you want onBackPressed() to be called as normal afterwards
}
}
)
If you have a Button or something else to perform an action then you can use
this.findNavController().popBackStack()

You need to set the MutableLiveData to null once the navigation is done.
For example
private val _name = MutableLiveData<String>()
val name: LiveData<String>
get() = _name
fun printName(){
_name.value = "John"
}
fun navigationComplete(){
_name.value = null
}
Now say you are observing the "name" in your fragment and you are doing some navigation once the name is John then should be like that:
viewModel.name.observe(viewLifecycleOwner, Observer { name ->
when (name) {
"John" -> {
this.findNavController() .navigate(BlaBlaFragmentDirections.actionBlaBlaFragmentToBlaBlaFragment())
viewModel.navigationComplete()
}
}
})
Now your back button will be working without a single problem.
Some data are almost used only once, like a Snackbar message or navigation event therefore you must tell set the value to null once done used.
The problem is that the value in _name remains true and it’s not possible to go back to previous fragment.

If you use Moxy or similar libs, checkout the strategy when you navigate from one fragment to second.
I had the same issue when strategy was AddToEndSingleStrategy.
You need change it to SkipStrategy.
interface ZonesListView : MvpView {
#StateStrategyType(SkipStrategy::class)
fun navigateToChannelsList(zoneId: String, zoneName: String)
}

Call onBackPressed in OnCreateView
private fun onBackPressed() {
requireActivity().onBackPressedDispatcher.addCallback(this) {
//Do something
}
}

For everyone who is using LiveData for setting navigation ids, there's no need to use SingleLiveEvent. You can just set the destinationId as null after you set its initial value.
For instance if you want to navigate from Fragment A to B.
ViewModel A:
val destinationId = MutableLiveData<Int>()
fun onNavigateToFragmentB(){
destinationId.value = R.id.fragmentB
destinationId.value = null
}
This will still trigger the Observer in the Fragment and will do the navigation.
Fragment A
viewModel.destinationId.observe(viewLifecycleOwner, { destinationId ->
when (destinationId) {
R.id.fragmentB -> navigateTo(destinationId)
}
})

The Simplest Answer for your problem (If it has something to do with fragments - Bottom navigation) could be
To set defaultNavHost = "false"
From Official Documentation it says->
Let's say you have 3 fragments set for Bottom Navigation, then setting
"defaultNavHost = true" will make fragment A acts like a parent, so when user clicks on back button in fragment 3 , it comes to fragment 1 instead of closing the activity (Bottom Navigation as Example).
Your XML should look like this, if you wanna just press back and close the activity from any fragment you are in.
<fragment
android:id="#+id/fragmentContainerView"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="#+id/bottom_nav"
app:defaultNavHost="false"
app:navGraph="#navigation/visit_summary_navigation" />

Set the MutableLiveData to false after navigation
Put this code in your ViewModel.kt
private val _eventNextFragment = MutableLiveData<Boolean>()
val eventNextFragment: LiveData<Boolean>
get() = _eventNextFragment
fun onNextFragment() {
_eventNextFragment.value = true
}
fun onNextFragmentComplete(){
_eventNextFragment.value = false
}
Let's say you want to navigate to another fragment, you'll call the onNextFragmentComplete method from the viewModel immediately after navigating action.
Put this code in your Fragment.kt
private fun nextFragment() {
val action = actionFirstFragmentToSecondFragment()
NavHostFragment.findNavController(this).navigate(action)
viewModel.onNextFragmentComplete()
}

I had faced the same issue due to the below "run blocking" code block. So don't use it if not necessary.

Android Navigation Component : Pass value (arguments) in fragments

What I have done:
I have created Navigation Drawer Activity, As updated new format of Navigation Drawer Activity, As per new Android architecture, I got it with Navigation Component structure.
The NavigationView code with NavController and NavigationUI is below which is opening fragment when I click on any navigation item.
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_profile, R.id.nav_privacy_policy,
R.id.nav_terms, R.id.nav_contact_us, R.id.nav_share, R.id.nav_send)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
This is for nav_host_fragment:
<fragment
android:id="#+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:navGraph="#navigation/mobile_navigation" />
The navigation is happening using this navigation/mobile_navigation.xml
<?xml version="1.0" encoding="utf-8"?>
<navigation 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/mobile_navigation"
app:startDestination="#+id/nav_home">
<fragment
android:id="#+id/nav_home"
android:name="com.sohamerp.marsremedies.fragment.HomeFragment"
android:label="#string/menu_home"
tools:layout="#layout/fragment_home" />
<fragment
android:id="#+id/nav_profile"
android:name="com.sohamerp.marsremedies.fragment.ProfileFragment"
android:label="#string/menu_my_profile"
tools:layout="#layout/fragment_profile" />
<fragment
android:id="#+id/nav_privacy_policy"
android:name="com.sohamerp.marsremedies.fragment.PrivacyPolicyFragment"
android:label="#string/menu_privacy_policy"
tools:layout="#layout/fragment_privacy_policy" />
<fragment
android:id="#+id/nav_terms"
android:name="com.sohamerp.marsremedies.fragment.TermsConditionFragment"
android:label="#string/menu_terms"
tools:layout="#layout/fragment_terms_condition" />
<fragment
android:id="#+id/nav_contact_us"
android:name="com.sohamerp.marsremedies.fragment.ContactUsFragment"
android:label="#string/menu_contact_us"
tools:layout="#layout/fragment_terms_condition" />
</navigation>
What I want to do:
Now I want to pass some values as a bundle (arguments) in Fragment when it's called.
Scenario: I have two fragments PrivacyPolicyFragment and TermsConditionsFragment, In both fragments, I am just opening links inside WebView accordingly. So When I click on the menu item of Privacy Policy, I will pass a link related to the same.
In this new structure navigation/mobile_navigation.xml opening fragments, How can I pass arguments?
Any help?

So I forgot to go through this link : Define Destination Arguments
But this answer helpful to all lazy peoples like me:
Add dependency in project level build.gradle:
classpath "androidx.navigation:navigation-safe-args-gradle-plugin:2.1.0"
Apply plugin in app level build.gradle:
apply plugin: "androidx.navigation.safeargs"
Using XML: predefined (static) value:
In xml file of navigation /navigation/mobile_navigation.xml declare argument tag as below or you can design through this link:
<fragment
android:id="#+id/nav_privacy_policy"
android:name="com.sohamerp.marsremedies.fragment.PrivacyPolicyFragment"
android:label="#string/menu_privacy_policy"
tools:layout="#layout/fragment_privacy_policy" >
<argument
android:name="privacyPolicyLink"
app:argType="string"
android:defaultValue="http://sohamerp.com/avo/avo_privacy_policy.html"/>
</fragment>
<fragment
android:id="#+id/nav_terms"
android:name="com.sohamerp.marsremedies.fragment.PrivacyPolicyFragment"
android:label="#string/menu_terms"
tools:layout="#layout/fragment_terms_condition" >
<argument
android:name="privacyPolicyLink"
app:argType="string"
android:defaultValue="http://sohamerp.com/avo/avo_privacy_policy.html"/>
</fragment>
Now you have to write code in your Fragment like:
if(getArguments() != null) {
// The getPrivacyPolicyLink() method will be created automatically.
String url = PrivacyPolicyFragmentArgs.fromBundle(getArguments()).getPrivacyPolicyLink();
}
Hope it will helps you others.

Simple and fast solution:
pass arguments between destinations
Bundle bundle = new Bundle();
bundle.putString("amount", amount);
Navigation.findNavController(view).navigate(R.id.confirmationAction, bundle);
and receiving
TextView tv = view.findViewById(R.id.textViewAmount);
tv.setText(getArguments().getString("amount"));

In this scenario, you can use
private NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
// Create the Bundle to pass, you can put String, Integer, or serializable object
Bundle bundle = new Bundle();
bundle.putString("link","http://yourlink.com/policy");
bundle.putSerializable("USER", user); // Serializable Object
navController.navigate(R.id.nav_terms, bundle); // called fragment with agruments
In case of any help you can reply on it

To pass arguments to other Fragments/Destinations, use Safe Args which ensures type safety. Just like #bromden illustrated, Safe Args will generate a class for each fragment/destination where an action originates. You can then pass the arguments into the action that navigates to the Fragments.
In the receiving fragment, say PrivacyFragment if your code is in Kotlin, use by navArgs() property delegate to access the arguments. i.e.
val args: PrivacyFragmentArgs by navArgs()
To better understand this, visit Pass data between destinations

In newer version of Android Studio 3.2+, below dependency and plug-in need to add in both build.gradle file
Step-1
Add dependency in Project-Level build.gradle
dependencies {
classpath 'androidx.navigation:navigation-safe-args-gradle-plugin:2.3.5'
}
Apply plugins in App-Level build.gradle
plugins {
id 'androidx.navigation.safeargs'
}
Step-2
In Navigation file, res/navigation/nav_graph.xml
Declare argument tag in any fragment or inner fragment with action tag
List item
Sample xml code
<fragment
android:id="#+id/nav_register"
android:name="com.pd.demo.ui.profile.RegisterFragment"
android:label="#string/title_register"
tools:layout="#layout/fragment_register">
<action
android:id="#+id/action_nav_register_to_nav_verify_otp"
app:destination="#id/nav_verify_otp">
<argument
android:name="mobile"
app:argType="string" />
<argument
android:name="password"
app:argType="string" />
</action>
</fragment>
Step-3
Below Kotlin code, pass argument to destination fragment
val bundle = bundleOf("mobile" to binding.etMobileNo.text.toString().trim())
Navigation.findNavController(binding.root).navigate(R.id.action_nav_register_to_nav_verify_otp, bundle)
Step-4
Below Kotlin code, get bundle argument from source fragment
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
mobileNo = arguments!!.getString("mobile").toString()
password = arguments!!.getString("password").toString()
}
This code will helps

You could implement NavigationView.OnNavigationItemSelectedListener
And do something like this:
override fun onNavigationItemSelected(item: MenuItem): Boolean {
drawer_layout.closeDrawers()
if (item.itemId == nv_navigation_drawer_navigation_view.checkedItem?.itemId)
return false
Handler().postDelayed({
when (item.itemId) {
R.id.nav_privacy_policy -> {
val action = FragmentDirections.actionFragmentToPrivacyFragment("Policy link")
findNavController().navigate(action)
}
}
}, DRAWER_NAVIGATION_DELAY)
return true
}
And in xml you can add argument to the recieving fragment, in this case
<fragment
android:id="#+id/nav_privacy_policy"
android:name=".fragment.PrivacyPolicyFragment"
android:label="#string/menu_privacy_policy"
tools:layout="#layout/fragment_privacy_policy">
<argument
android:name="policy"
app:argType="string" />
</fragment>

You can also pass serializable objects, enum values and arrays of primitive types.
For example:
enum class ObjectType : Serializable {
FIRST, SECOND
}
Then, add arguments to the xml
<fragment
android:id="#+id/nav_profile"
android:name="com.sohamerp.marsremedies.fragment.ProfileFragment"
android:label="#string/menu_my_profile"
tools:layout="#layout/fragment_profile" >
<argument
android:name="myObjectType"
android:defaultValue="SECOND"
app:argType="com.project.app.data.ObjectType" />
</fragment>
Note, that you should specify complete path!

Passing data from the start destination with NavController NavGraph navigate is straightforward. I use this to display order lines associated to an order header:
private void showRepositionLinesFragment(AppObjects.RepOrderHeader orderHeader) {
int number = orderHeader.getOrderNumber();
String orderNumber = String.format("%06d",number);
String createDate = orderHeader.getCreateDate();
Globals.LogTrace(this, AppAlertDialog.DialogType.Info,
"Navigate to FragRepoLines with orderNumber: " + orderNumber,false);
NavController navController = NavHostFragment.findNavController(FragmentRepositionHeaders.this);
Bundle bundle = new Bundle();
bundle.putString(getString(R.string.arg_header_ordernumber),orderNumber);
bundle.putString(getString(R.string.arg_repheader_createdate), createDate);
navController.getGraph().findNode(R.id.FragRepoLines).setLabel(orderNumber + " " + createDate);
navController.navigate(R.id.action_FragRepoHeaders_to_FragRepoLines,bundle);
}
Getting data from the fragment that handles the order lines turned to be more complicated. Tried for hours with NavController getArguments().
In the end this is what worked for me.
In the start fragment:
NavController navController = NavHostFragment.findNavController(this);
// We use a String here, but any type that can be put in a Bundle is supported
MutableLiveData<String> liveData = navController.getCurrentBackStackEntry()
.getSavedStateHandle()
.getLiveData(getString(R.string.arg_header_ordernumber));
liveData.observe(getViewLifecycleOwner(), new Observer<String>() {
#Override
public void onChanged(String s) {
Globals.LogTrace(this, AppAlertDialog.DialogType.Info, "+++++++++ liveData changed -> " + s, false);
}
});
In the destination fragment:
String arg = getString(R.string.arg_header_ordernumber);
NavController navController = NavHostFragment.findNavController(this);
NavBackStackEntry navBackStackEntry = navController.getCurrentBackStackEntry();
if (navBackStackEntry != null) {
SavedStateHandle savedStateHandle = navBackStackEntry.getSavedStateHandle();
if (savedStateHandle != null) {
savedStateHandle.set(arg, "000000");
} else {
Globals.LogTrace(this, AppAlertDialog.DialogType.Info,"savedStateHandle == null",false);
}
} else {
Globals.LogTrace(this, AppAlertDialog.DialogType.Info,"navBackStackEntry == null",false);
}
Source: Interact programmatically with the Navigation component
I changed the navController.getPreviousBackStackEntry() for navController.getCurrentBackStackEntry()

I had the same issue but I´m still not able to pass the arguments using fragment directions. Since I need the value in several of my fragments I decided to use a companion object in my main activity. It´s probably not the best but it solves the problem:
class MainActivity : AppCompatActivity() {
companion object{
var myGlobalVar = "Example"
}
override fun onCreate(savedInstanceState: Bundle?) {....
Then I can access its value in all of my fragments by importing it:
import myAppPackage.MainActivity.Companion.myGlobalVar
I had to delete the argument from my navGraph but i can still access it in the background.

How to set title in app bar with Navigation Architecture Component

I was trying out Navigation architecture component and is now having difficulties in setting the title. How do I set the title programmatically and also how it works?
To clear my question, let's have an example, where, I've set up a simple app with MainActivity hosting the navigation host controller, the MainFragment has a button and on clicking the button it goes to DetailFragment.
The same code from another question of multiple app bars on stack-overflow.
MainActivity
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
// Setting up a back button
NavController navController = Navigation.findNavController(this, R.id.nav_host);
NavigationUI.setupActionBarWithNavController(this, navController);
}
#Override
public boolean onSupportNavigateUp() {
return Navigation.findNavController(this, R.id.nav_host).navigateUp();
}
}
MainFragment
public class MainFragment extends Fragment {
public MainFragment() {
// Required empty public constructor
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_main, container, false);
}
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
Button buttonOne = view.findViewById(R.id.button_one);
buttonOne.setOnClickListener(Navigation.createNavigateOnClickListener(R.id.detailFragment));
}
}
DetailFragment
public class DetailFragment extends Fragment {
public DetailFragment() {
// Required empty public constructor
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_detail, container, false);
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout 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"
android:animateLayoutChanges="true"
tools:context=".MainActivity">
<com.google.android.material.appbar.AppBarLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:animateLayoutChanges="true"
android:theme="#style/AppTheme.AppBarOverlay">
<androidx.appcompat.widget.Toolbar
android:id="#+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="#style/AppTheme.PopupOverlay" />
</com.google.android.material.appbar.AppBarLayout>
<fragment
android:id="#+id/nav_host"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="top"
android:layout_marginTop="?android:attr/actionBarSize"
app:defaultNavHost="true"
app:layout_anchor="#id/bottom_appbar"
app:layout_anchorGravity="top"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
app:navGraph="#navigation/mobile_navigation" />
<com.google.android.material.bottomappbar.BottomAppBar
android:id="#+id/bottom_appbar"
android:layout_width="match_parent"
android:layout_height="?android:attr/actionBarSize"
android:layout_gravity="bottom" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/fab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_anchor="#id/bottom_appbar" />
</androidx.coordinatorlayout.widget.CoordinatorLayout>
navigation.xml
<navigation 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/mobile_navigation"
app:startDestination="#id/mainFragment">
<fragment
android:id="#+id/mainFragment"
android:name="com.example.MainFragment"
android:label="fragment_main"
tools:layout="#layout/fragment_main" >
<action
android:id="#+id/toAccountFragment"
app:destination="#id/detailFragment" />
</fragment>
<fragment
android:id="#+id/detailFragment"
android:name="com.example.DetailFragment"
android:label="fragment_account"
tools:layout="#layout/fragment_detail" />
</navigation>
So when start my app, the title is "MainActivity". As usual it shows the MainFragment that contains the button to go to DetailFragment. In the DialogFragment I've set the title as:
getActivity().getSupportActionBar().setTitle("Detail");
First Problem: So clicking the button on the MainFragment to goto DetailFragment, it does go there and the title changes to "Detail". But on clicking the back button, the title changes to "fragment_main". So I added this line of code to MainFragment:
#Override
public void onViewCreated(#NonNull View view, #Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
// ...
//Showing the title
Navigation.findNavController(view)
.getCurrentDestination().setLabel("Hello");
}
Now the while returning back from DetailFragment to MainFragment the title changes to "Hello". But here comes the second problem, when I close the app and start again, the title changes back to "MainActivity" though it should be showing "Hello" instead, know?
Ok, then adding setTitle("Hello") in MainFrgment is not working too. For example, the activity starts and the title is "Hello", go to DetailsFragment and press the back button again, the title goes back to "fragment_main".
The only solution is to have both setTitle("Hello") along with Navigation.findNavController(view).getCurrentDestination().setLabel("Hello") in MainFragment.
So what is the proper way to show the title for fragments using Navigation Component?

It's actually because of:
android:label="fragment_main"
Which you have set in the xml.
So what is the proper way to show the title for Fragments using
Navigation Component?
setTitle() works at this point. But, because you set label for those Fragments, it might show the label again when recreating the Activity. The solution will probably be deleting android:label and then do your things with code:
((AppCompatActivity) getActivity()).getSupportActionBar().setTitle("your title");
Or:
((AppCompatActivity) getActivity()).getSupportActionBar().setSubtitle("your subtitle");
In onCreateView().
Found a workaround:
interface TempToolbarTitleListener {
fun updateTitle(title: String)
}
class MainActivity : AppCompatActivity(), TempToolbarTitleListener {
...
override fun updateTitle(title: String) {
binding.toolbar.title = title
}
}
Then:
(activity as TempToolbarTitleListener).updateTitle("custom title")
Check this out too:Dynamic ActionBar title from a Fragment using AndroidX Navigation

As others are still participating in answering this question, let me answer my own question as APIs has changed since then.
First, remove android:label from the fragment/s that you wish to change the title of, from within navigation.xml (aka Navigation Graph),.
Now you can change the title from with the Fragment by calling
(requireActivity() as MainActivity).title = "My title"
But the preferred way you should be using is the API NavController.addOnDestinationChangedListener from within MainActivity. An Example:
NavController.OnDestinationChangedListener { controller, destination, arguments ->
// compare destination id
title = when (destination.id) {
R.id.someFragment -> "My title"
else -> "Default title"
}
// if (destination == R.id.someFragment) {
// title = "My title"
// } else {
// title = "Default Title"
// }
}

You can use this code in your fragment if you don't specify your app bar(default appbar)
(activity as MainActivity).supportActionBar?.title = "Your Custom Title"
Remember to delete the android:label attribute in your navigation graph
Happy code ^-^

From experience, NavController.addOnDestinationChangedListener
Seems to perform well. My example below on my MainActivity did the magic
navController.addOnDestinationChangedListener{ controller, destination, arguments ->
title = when (destination.id) {
R.id.navigation_home -> "My title"
R.id.navigation_task_start -> "My title2"
R.id.navigation_task_finish -> "My title3"
R.id.navigation_status -> "My title3"
R.id.navigation_settings -> "My title4"
else -> "Default title"
}
}

There is a much easier way to achieve this nowadays with Kotlin and androidx.navigation:navigation-ui-ktx:
import androidx.navigation.ui.setupActionBarWithNavController
class MainActivity : AppCompatActivity() {
private val navController: NavController
get() = findNavController(R.id.nav_host_fragment)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this,R.layout.activity_main)
setSupportActionBar(binding.toolbar)
setupActionBarWithNavController(navController) // <- the most important line
}
// Required by the docs for setupActionBarWithNavController(...)
override fun onSupportNavigateUp() = navController.navigateUp()
}
That's basically it. Don't forget to specify android:label in your nav graphs.

You can use the navigation graph xml file and set the label of the fragment to an argument.
Then, in your parent fragment, you can pass an argument using SafeArgs (please, follow the guide on https://developer.android.com/guide/navigation/navigation-pass-data#Safe-args to set up SafeArgs) and provide a default value to avoid the title being null or empty.
<!--this is originating fragment-->
<fragment
android:id="#+id/fragmentA"
android:name=".ui.FragmentA"
tools:layout="#layout/fragment_a">
<action
android:id="#+id/fragmentBAction"
app:destination="#id/fragmentB" />
</fragment>
<!--set the fragment's title to a string passed as an argument-->
<!--this is a destination fragment (assuming you're navigating FragmentA to FragmentB)-->
<fragment
android:id="#+id/fragmentB"
android:name="ui.FragmentB"
android:label="{myTitle}"
tools:layout="#layout/fragment_b">
<argument
android:name="myTitle"
android:defaultValue="defaultTitle"
app:argType="string" />
</fragment>
In originating Fragment:
public void onClick(View view) {
String text = "text to pass as a title";
FragmentADirections.FragmentBAction action = FragmentADirections.fragmentBAction();
action.setMyTitle(text);
Navigation.findNavController(view).navigate(action);
}
FragmentADirections and FragmentBAction -
These classes are autogenerated from IDs in your nav_graph.xml file.
In 'your action ID + Action' type classes you can find auto-generated setter methods, which you can use to pass arguments
In your receiving destination, you call auto-generated class {your receiving fragment ID}+Args
FragmentBArgs.fromBundle(requireArguments()).getMyTitle();
Please refer to the official guide at
https://developer.android.com/guide/navigation/navigation-pass-data#Safe-args

NavigationUI.setupActionBarWithNavController(this, navController)
Don't forget to specify android:label for your fragments in your nav graphs.
To navigate back:
override fun onSupportNavigateUp(): Boolean {
return NavigationUI.navigateUp(navController, null)
}

I've spent a couple of hours trying to do a very simple thing such as changing the bar title of a detail fragment when navigating from a particuler item on a master fragment. My daddy always said to me: K.I.S.S. Keep it simple son.
setTitle() crashed, interfaces are cumbersome, came up with a (very) simple solution in terms of lines of code, for the latest fragment navigation implementation.
In the master fragment resolve the NavController, get the NavGraph, find the destination Node, set the Title, and last but not least navigate to it:
//----------------------------------------------------------------------------------------------
private void navigateToDetail() {
NavController navController = NavHostFragment.findNavController(FragmentMaster.this);
navController.getGraph().findNode(R.id.FragmentDetail).setLabel("Master record detail");
navController.navigate(R.id.action_FragmentMaster_to_FragmentDetail,null);
}

The API may have changed since the question was asked, but now you may indicate a reference to a string in your app resources in the navigation graph label.
This is pretty helpful if you want a static title for your fragments.

delete detatil fragment's label in navigation graph xml file.
then pass the prefered title through arguments to destination fragment which needs title like so.
The First Fragment code - Start point
findNavController().navigate(
R.id.action_FirstFragment_to_descriptionFragment,
bundleOf(Pair("toolbar_title", "My Details Fragment Title"))
)
as you see I sent as pair in arguments bundle when navigating to Destination Fragment
so in your Destination Fragment get title from arguments in onCreate method like this
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
toolbarTitle = requireArguments().getString("toolbar_title", "")
}
then use it to change Main Activity's title in onCreateView method like this
requireActivity().toolbar.title = toolbarTitle

I would suggest to include AppBar in each screen.
To avoid code duplicates, create a helper, that builds AppBar, taking the title as a parameter. Then invoke the helper in each screen class.

Another approach could be this:
fun Fragment.setToolbarTitle(title: String) {
(activity as NavigationDrawerActivity).supportActionBar?.title = title
}

Update title with either label in navigation xml or exclude labels and set with requiresActivity().title Supports mixing the two ways for screens with and without dynamic titles. Works for me with a Compose UI toolbar and Tabs.
val titleLiveData = MutableLiveData<String>()
findNavController().addOnDestinationChangedListener { _, destination, _ ->
destination.label?.let {
titleLiveData.value = destination.label.toString()
}
}
(requireActivity() as AppCompatActivity).setSupportActionBar(object: Toolbar(requireContext()) {
override fun setTitle(title: CharSequence?) {
titleLiveData.value = title.toString()
}
})
titleLiveData.observe(viewLifecycleOwner, {
// Update your title
})

android:label="{title_action}"
<?xml version="1.0" encoding="utf-8"?>
<navigation
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/nav_graph"
app:startDestination="#id/FirstFragment">
<fragment
android:id="#+id/FirstFragment"
android:name="com.example.contact2.FirstFragment"
android:label="#string/first_fragment_label"
tools:layout="#layout/fragment_first">
<action
android:id="#+id/action_FirstFragment_to_SecondFragment"
app:destination="#id/SecondFragment"
app:enterAnim="#anim/nav_default_enter_anim"
app:exitAnim="#anim/nav_default_exit_anim"
app:popEnterAnim="#anim/nav_default_pop_enter_anim"
app:popExitAnim="#anim/nav_default_pop_exit_anim" />
</fragment>
<fragment
android:id="#+id/SecondFragment"
android:name="com.example.contact2.SecondFragment"
android:label="{title_action}"
tools:layout="#layout/fragment_second">
<action
android:id="#+id/action_SecondFragment_to_FirstFragment"
app:destination="#id/FirstFragment"
app:enterAnim="#anim/nav_default_enter_anim"
app:exitAnim="#anim/nav_default_exit_anim"
app:popEnterAnim="#anim/nav_default_pop_enter_anim"
app:popExitAnim="#anim/nav_default_pop_exit_anim" />
<argument
android:name="title_action"
app:argType="string"
app:nullable="true" />
</fragment>
</navigation>

Anyway few of those answers I tried did not work for then I decided to do it the old Java way in Kotlin using interface
Created an interface as shown below.
interface OnTitleChangeListener {
fun onTitleChange(app_title: String)
}
Then made my activity to implement this interface as shown below.
class HomeActivity : AppCompatActivity(), OnTitleChangeListener {
override fun onTitleChange(app_title: String) {
title = app_title
}
}
How on my fragment's on activity attache I this this
override fun onAttach(context: Context) {
super.onAttach(context)
this.currentContext = context
(context as HomeActivity).onTitleChange("New Title For The app")
}

The simple solution:
Layout
androidx.coordinatorlayout.widget.CoordinatorLayout
com.google.android.material.appbar.AppBarLayout
com.google.android.material.appbar.MaterialToolbar
androidx.constraintlayout.widget.ConstraintLayout
com.google.android.material.bottomnavigation.BottomNavigationView
fragment
androidx.navigation.fragment.NavHostFragment
Activity
binding = DataBindingUtil.setContentView(this, layoutRes)
setSupportActionBar(binding.toolbar)
val controller = findNavController(R.id.nav_host)
val configuration = AppBarConfiguration(
setOf(
R.id.navigation_home,
R.id.navigation_dashboard,
R.id.navigation_notifications
)
)
setupActionBarWithNavController(controller, configuration)
navView.setupWithNavController(controller)

It could be helpful if you would like to change the title of Toolbar programmatically with low cohesion code between Activity and Fragment.
class DetailsFragment : Fragment() {
interface Callbacks {
fun updateTitle(title: String)
}
private var listener: Callbacks? = null
override fun onAttach(context: Context) {
super.onAttach(context)
// keep activity as interface only
if (context is Callbacks) {
listener = context
}
}
override fun onDetach() {
// forget about activity
listener = null
super.onDetach()
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View =
inflater.inflate(R.layout.fragment_details, container, false)
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
listener?.updateTitle("Dynamic generated title")
}
}
class MainActivity : AppCompatActivity(), DetailsFragment.Callbacks {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
override fun updateTitle(title: String) {
supportActionBar?.title = title
}
}

September 4, 2021
Using Kotlin in my case this is solution. use this code in MainActivity
val navController = this.findNavController(R.id.myNavHostFragment)
navController.addOnDestinationChangedListener { controller, destination, arguments ->
destination.label = when (destination.id) {
R.id.homeFragment -> resources.getString(R.string.app_name)
R.id.roomFloorTilesFragment -> resources.getString(R.string.room_floor_tiles)
R.id.roomWallTilesFragment -> resources.getString(R.string.room_wall_tiles)
R.id.ceilingRateFragment -> resources.getString(R.string.ceiling_rate)
R.id.areaConverterFragment -> resources.getString(R.string.area_converter)
R.id.unitConverterFragment -> resources.getString(R.string.unit_converter)
R.id.lenterFragment -> resources.getString(R.string.lenter_rate)
R.id.plotSizeFragment -> resources.getString(R.string.plot_size)
else -> resources.getString(R.string.app_name)
}
}
NavigationUI.setupActionBarWithNavController(...)
NavigationUI.setupWithNavController(...)

Jetpack Navigation deeplink with query parameters

it looks like it isn't possible to process a deeplink with query parameters in the new Jetpack Navigation library. If you put the following to the navigation.xml:
<deepLink app:uri="scheme://host/path?query1={query_value}" /> then the deeplink does not open the fragment.
After some digging I found that the culprit is probably in the NavDeepLink when it transforms the url from xml to a Pattern regex. Looks like the problem is a question mark that is not excaped.
I wrote a test which fails:
#Test
fun test() {
val navDeepLink = NavDeepLink("scheme://host/path?query1={query_value}")
val deepLink = Uri.parse("scheme://host/path?query1=foo_bar")
assertEquals(true, navDeepLink.matches(deepLink))
}
To make the test pass all I have to do is to escape the ? as following:
#Test
fun test() {
val navDeepLink = NavDeepLink("scheme://host/path\\?query1={query_value}")
val deepLink = Uri.parse("scheme://host/path?query1=foo_bar")
assertEquals(true, navDeepLink.matches(deepLink))
}
Am I missing something really basic here to pass query values to my Fragment or is this not supported feature at the moment?

You need to add DeepLink Navigation to AndroidManifest.xml ( special Activity that handles the fragment) so when deeplink clicked your app can receive the DeepLink and pass it to that navigation and fragment & can read it as argument:
I'll put Kotlin codes here :
In your navigation file, your fragment that gonna handle the deeplink with arguements must be like this:
<fragment
android:id="#+id/menu"
android:name="ir.hamplus.fragments.MainFragment"
android:label="MainFragment">
<action android:id="#+id/action_menu_to_frg_messenger_main"
app:destination="#id/frg_messenger_main"/>
<deepLink app:uri="http://hamplus.ir/request/?key={key}&id={id}" />
<argument android:name="key" app:argType="string"/>
<argument android:name="id" app:argType="string"/>
</fragment>
read deeplink arguments in frasgment /Activity :
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
//Or in activity read the intent?.data
arguments?.let {
Log.i("TAG", "Argument=$arguments")
var key = it.getString("key")
Log.i("TAG", "key=$key")
var id = it.getString("id")
Log.i("TAG", "id=$id")
}
}
Also add the nav-graph on AndroidManifest.xml in related Activity :
<activity
android:name=".MainActivity"
android:theme="#style/AppTheme.NoActionBar" >
<nav-graph android:value="#navigation/main_navigation"/>
</activity>

package androidx.navigation
import android.net.Uri
import androidx.test.runner.AndroidJUnit4
import org.junit.Assert.assertTrue
import org.junit.Test
import org.junit.runner.RunWith
#RunWith(AndroidJUnit4::class)
class NavTest {
#Test
fun test() {
val navDeepLink = NavDeepLink("scheme://host/path\\?query1={query_value1}&query2={query_value2}")
val deepLink = Uri.parse("scheme://host/path?query1=foo_bar&query2=baz")
val bundle = navDeepLink.getMatchingArguments(deepLink)!!
assertTrue(bundle.get("query_value1") == "foo_bar")
assertTrue(bundle.get("query_value2") == "baz")
}
}
In the end it looks like NavDeepLink treats non escaped as "?" match-zero-or-one quantifier. You need to escape it. In other words, we have a leak of non documented implementation detail.
It might be not related to the exactly this case, but there is some similar issues with escaping "&" with "\" when using add command.
The issue was also touched in the following channel.